# Frequency-Ridership Spirals

I was reticent to post about this topic; I polled it on Patreon in December and it got just under 50% while the two topics I did blog, difficult urban geography and cross-platform transfers, got 64% and 50% respectively. However, between how close the vote was and the conversation about the current state of the subway in New York, I felt obligated to explain what’s been going on. The short version is that practically the entire change in subway ridership in New York over the last generation or two has come from the off-peak, and the way American cities set their frequency guidelines off-peak amplify small changes in demand, so that a minor setback can lead to collapse and a minor boost can lead to boom.

The good news is that by setting frequency to be high even if it does not look like ridership justifies it, cities can generate a virtuous cycle on the upswing and avoid a vicious one on the downswing. However, it requires the discipline to run good service even in bad times, when bean counters and budget cutters insist on retrenchment. The Chainsaw Al school of management looks appealing in recessions or when ridership is falling, and this is precisely when people who run transit agencies must resist the urge to cut frequency to levels that lead to a positive feedback loop wrecking the system.

Ridership-frequency elasticity

The key to the frequency-ridership spiral is that cutting frequency on transit makes it less useful to passengers, since door-to-door trip times are longer and less reliable. The size of this effect can be measured as the elasticity of ridership with respect to service: if increasing service provision by 1% is demonstrated to raise ridership by e%, we say that the elasticity is e.

Fortunately, this question is fundamental enough to transit that there is extensive published literature on the subject:

• In a classical TRB paper, Armando Lago, Patrick Mayworm, and Matthew McEnroe look at data from several American cities as well as one British one, disaggregating elasticity by frequency, mode (bus or commuter rail), and period (peak or off-peak). The aggregate average value is e = 0.44 for buses and e = 0.5 for commuter rail, but when frequency is better than every 10 minutes, e = 0.22 on average.
• Todd Litman of the advocacy organization VTPI has a summary mostly about fare elasticity but also service elasticity, suggesting e is in the 0.5-0.7 range in the short term and in the 0.7-1.1 range in the long term.
• A paper by Joe Totten and David Levinson includes its own lit review of several studies, including the two above, finding a range of 0.3 to 1.1 across a number of papers, with the lower figures associated with urban service and the higher ones with low-frequency suburban service. The paper’s own research, focusing on transit in Minneapolis, finds that on weekdays, e = 0.39.

One factor that I have unfortunately not seen in the papers I have read is trip length. Frequency is more important for short trips than long ones. This is significant, since when the headway is shorter relative to in-vehicle trip time we should expect lower elasticity with respect to the headway. Waiting 10 minutes rather than 5 minutes for an hour-long trip is not much of an imposition; waiting 30 minutes rather than 15 for the same trip is a greater imposition, as is waiting 10 minutes rather than 5 for a 20-minute trip.

In New York, the average unlinked subway trip is 13.5 minutes long, so the difference between 10 and 5 minutes is very large. Lago-Mayworm-McEnroe cite research saying passengers’ disutility for out-of-vehicle time is 2-3 times as large as for in-vehicle time; the MTA’s own ridership screen states that this penalty is 1.75, the MBTA’s states that it is 2.25, and a study by Coen Teulings, Ioulina Ossokina, and Henri de Groot says that it is 2 in the Netherlands. Figuring that this penalty is 2, the worst-case scenario for off-peak weekday wait time in New York, 10 minutes, has passengers spending more perceived time waiting for the train than riding it, and even in the average case, 10/2 = 5 minutes, it is close. In that case, higher values of e are defensible. Lago-Mayworm-McEnroe have less data about in-vehicle time elasticity and do not attempt to aggregate in- and out-of-vehicle time. But adding everything together is consistent with e = 0.8 relative to speed averaged over the total wait and in-vehicle time, and then e is maybe 0.4 relative to frequency.

The impact of service cuts

If the elasticity of ridership relative to frequency is 0.4, then cutting service by 1% means cutting ridership by 0.4%. If half the operating costs are covered by fares, then revenue drops by 0.2% of total operating expenses, so the 1% cut only saves 0.8% of the total subsidy. Achieving a 1% cut in operating costs net of fare revenue thus requires a 1.25% cut in service, which reduces ridership by 0.5%.

This may not sound too bad, but that’s because the above analysis does not incorporate fixed costs. Rail comes equipped with fixed costs for maintenance, station staffing, rolling stock, and administration, regardless of how much service the agency runs. Lisa Schweitzer uses this fact to defend Los Angeles’s MTA from my charge of high operating costs: she notes that Los Angeles runs much less service than my comparison cases in the US and Europe and thus average cost per train-km is higher even without undue inefficiency. In contrast, bus costs are dominated by driver wages, which are not fixed.

New York does not keep a headcount of transit employees in a searchable format – the Manhattan Institute’s See Through New York applet helps somewhat but is designed around shaming workers who make a lot of money through overtime rather than around figuring out how many people work (say) maintenance. But Chicago does, and we can use its numbers to estimate the fixed and variable costs of running the L.

The CTA has somewhat more than 10,000 workers, split fairly evenly between bus and rail. The rail workers include about 800 working for the director of maintenance, working on the rolling stock, which needs regular servicing and inspections regardless of how often it’s run; 550 working for facilities maintenance; (say) 400 out of 800 workers in administrative capacity like communications, general counsel, purchasing, and the chief engineer’s office; 600 workers in power and way maintenance; nearly 1,000 customer service agents; and 450 workers in flagging, switching, and the control towers. Only 500 workers drive trains, called rapid transit operators or extra board, and there may charitably be another 200 clerks, managers, and work train operators whose jobs can be cut if there is a service cut. A service cut would only affect 15% of the workers, maybe 20% if some rolling stock maintenance work can be cut.

In New York the corresponding percentage is somewhat higher than 15% since trains have conductors. Train operators and conductors together are about 13% of the NYCT headcount, so maybe 20% of subway employees, or 25% with some extra avoidable maintenance work.

What this means is that achieving a 2% cut in subsidy through reducing service requires a service cut of much more than 2%. If only 25% of workers are affected then, even without any frequency-ridership elasticity, the agency needs to cut service by 8% to cut operating costs by 2%.

The Uber effect

The combination of elasticity and fixed costs means that rail ridership responds wildly to small shocks to ridership. For a start, if the agency cuts service by 1%, then operating costs fall by 0.25%. Ridership falls by 0.4%, and thus revenue also falls by 0.4%, which is 0.2% of total operating costs. Thus operating costs net of revenue only fall by 0.05%. The only saving grace is that this is 0.05% of total operating costs; since by assumption fare revenue covers half of operating costs, this saves a full 0.1% of the public subsidy.

Read the above paragraph again: taking fixed costs and elasticity into account, cutting service by 1% only reduces the public subsidy to rail service by 0.1%. A 2% cut in subsidy in a recession requires a brutal 20% cut in service, cutting ridership by 8%. And this only works because New York overstaffs its trains by a factor of 2, so that it’s plausible that 25% of employees can be furloughed in a service cut; using Chicago numbers this proportion is at most 20%, in which case revenue falls one-to-one with operating costs and there is no way to reduce the public subsidy to rail operations through service cuts.

Of course, this has a positive side: a large increase in service only requires a modest increase in the public subsidy. Moreover, if trains have the operating costs of Chicago, which are near the low end in the developed world, then the combined impact of fixed costs and elasticity is such that the public subsidy to rapid transit does not depend on frequency, and thus the agency could costlessly increase service.

This is relevant to the Uber effect – namely, the research arguing that the introduction of ride-hailing apps, i.e. Uber and Lyft, reduces transit ridership. I was skeptical of Bruce Schaller’s study to that effect since it came out two years ago, since the observed reduction in transit ridership in New York in 2016 was a large multiple of the increase in total taxi and ride-hailing traffic once one concentrated on the off-peak and weekends, when the latter rose the most.

But if small shocks to ridership are magnified by the frequency-ridership spiral, then the discrepancy is accounted for. If a shock cuts ridership by 1%, which could be slower trains, service disruptions due to maintenance, or the Uber effect, then revenue falls 1% and the subsidy has to rise 1% to compensate. To cover the subsidy through service cuts requires a 10% cut in service, further cutting ridership by 4%.

Off-peak service guidelines

The above analysis is sobering enough. However, it assumes that service cuts and increases are uniformly distributed throughout the day. This is not the actual case for American transit agency practice, which is to concentrate both cuts and increases in the off-peak.

Unfortunately, cuts in off-peak service rather than at rush hour do not touch semi-fixed labor costs. The number of employees required to run service is governed by the peak, so running a lot of peak service without off-peak service leads to awkward shift scheduling and poor crew utilization. Higher ratios of peak to base frequency correlate with lower total service-hours per train driver: in addition to the examples I cite in a post from 2016, I have data for Berlin, where the U-Bahn’s peak-to-base ratio is close to 1, and there are 829 annual service-hours per driver.

I discussed the fact that the marginal cost of adding peak service is several times that of adding off-peak service in a post from last year. However, even if we take rolling stock acquisition as a given, perhaps funded by a separate capital plan, marginal crew costs are noticeably higher at the peak than off-peak.

In New York, the rule is that off-peak subway frequency is set so that at the most crowded point of each route, the average train will be filled to 125% seated capacity; before the round of service cuts in 2010 this was set at 100%, so the service cut amounted to reducing frequency by 20%. The only backstop to a vicious cycle is that the minimum frequency on weekdays is set at 10 minutes; on weekends I have heard both 10 and 12 minutes as the minimum, and late at night there is a uniform 20-minute frequency regardless of crowding.

Peak frequency is governed by peak crowding levels as well, but much higher crowding than 125% is permitted. However, the busiest lines are more crowded than the guidelines and run as frequently as there is capacity for more trains, so there is no feedback loop there between ridership and service.

The saving grace is that revenue is less sensitive to off-peak ridership, since passengers who get monthly passes for their rush hour trips ride for free off-peak. However, this factor requires there to be substantial enough season pass discounts so that even rush hour-only riders would use them. Berlin, where U-Bahn tickets cost €2.25 apiece in bundles of 4 and monthly passes cost €81, is such a city: 18 roundtrips per month are enough to justify a monthly. New York is not: with a pay-per-ride bonus a single ride costs $2.62 whereas a 30-day pass costs$121, so 23.1 roundtrips per month are required, so the breakeven point requires a roundtrip every weekday and every other weekend.

New York subway ridership evolution

The subway’s crisis in the 1970s reduced ridership to less than 1 billion, a level not seen since 1918. This was on the heels of a steady reduction in ridership over the 1950s and 60s, caused by suburbanization. In 1991, ridership was down to 930 million, but the subsequent increase in reliability and fall in crime led to a 24-year rally to a peak of 1,760 million in 2015.

Throughout this period, there was no increase in peak crowding. On the contrary. Look at the 1989 Hub Bound Report: total subway ridership entering Manhattan south of 60th Street between 7 and 10 am averaged about 1 million, down from 1.1 million in 1971 – and per the 2016 report, the 2015 peak was only 922,000. Between 1989 and 2015, NYCT actually opened a new route into Manhattan, connecting the 63rd Street Tunnel to the Queens Boulevard Line; moreover, a preexisting route, the Manhattan Bridge, had been reduced from four tracks to two in 1986 and went back to four tracks in 2004.

Nor was there much of an increase in mode share. The metropolitan statistical area’s transit mode share for work trips rose from 27% in 2000 to 30% in 2010. In the city proper it rose from 52% in 1990 to 57% in 2016. No: more than 100% of the increase in New York subway ridership between 1991 and 2015 was outside the peak commute hours, and nearly 100% of it involved non-work trips. These trips are especially affected by the frequency-ridership spiral, since frequency is lower then, and thus a mild positive shock coming from better maintenance, a lower crime rate, and perhaps other factors translated to a doubling in total ridership, and a tripling of off-peak ridership. Conversely, today, a very small negative shock is magnified to a minor crisis, even if ridership remains well above the levels of the 1990s.

The way out

Managers like peak trains. Peak trains are full, so there’s no perception of wasting service on people who don’t use it. Managers also like peak trains because they themselves are likelier to ride them: they work normal business hours, and are rich enough to afford cars. That current NYCT head Andy Byford does not own a car and uses the city’s transit network to get around scandalizes some of the longstanding senior managers, who don’t use their own system. Thus, the instinct of the typical manager is to save money by pinching pennies on off-peak service.

In contrast, the best practice is to run more service where possible. In Berlin, nearly all U-Bahn trains run every 5 minutes flat; a few lines get 4-minute peak service, and a few outer ends and branches only get half-service, a train every 10 minutes. At such high frequency, the frequency-ridership spiral is less relevant: an increase to a train every 4 minutes would require increasing service by 25%, raising costs by around 5% (Berlin’s one-person crews are comparable to Chicago’s, not New York’s), but not result in a significant increase in ridership as the shorter headway is such a minute proportion of total travel time. However, New York’s 10-minute off-peak frequency is so low that there is room to significantly increase ridership purely by running more service.

In 2015 I criticized the frequency guidelines in New York on the grounds of branching: a complexly branched system must run interlined services at the same frequency, even if one branch of a trunk line is somewhat busier than the other. However, the frequency-ridership spiral adds another reason to discard the current frequency guidelines. All branches in New York should run at worst every 6 minutes during the daytime, yielding 3-minute frequency on most trunks, and the schedules should be designed to avoid conflicts at junctions; non-branching trunk lines, that is the 1, 6, 7, and L trains, should run more frequently, ideally no more than every 4 minutes, the lower figure than in Berlin following from the fact that the 1 and 6 trains are both local and mostly serve short trips.

Moreover, the frequency should be fixed by a repeating schedule, which should be clockface at least on the A train, where the outer branches would only get 12-minute frequency. If ridership increases by a little, trains should be a little more crowded, and if it decreases by a little, they should be a little less crowded. Some revision of schedules based on demand may be warranted but only in the long run, never in the short run. Ideally the system should aim at 5-minute frequency on every route, but as the N, R, and W share tracks, this would require some deinterlining in order to move more service to Second Avenue.

This increase in frequency is not possible if politicians and senior managers respond to every problem by cutting service while dragging their feet about increasing service when ridership increases. It requires proactive leadership, interested in increasing public transit usage rather than in avoiding scandal. But the actual monetary expense required for such frequency is not large, since large increases in frequency, especially in the off-peak, mostly pay for themselves through extra ridership. The initial outlay required to turn the vicious cycle into a virtuous one is not large; all that is required is interest from the people in charge of American transit systems.

# 30-30-30 is Feasible

This piece first appeared as a study attached to an article in the Connecticut Mirror by SE Coast’s Gregory Stroud.

Fresh off the election, Connecticut Governor Ned Lamont has proposed an ambitious infrastructure plan, dubbed 30-30-30, in which train travel between New York and Stamford, Stamford and New Haven, and New Haven and Hartford would be cut to 30 minutes. With an average speed of about 110 km/h, this is only about half the average speed typical of high-speed rail, but still slightly higher than that of the Northeast Regional between New York and Washington, which is competitive with cars and buses provided there is enough capacity.

For 30-30-30 to truly be cost-effective, the plan needs to speed up trains with relatively little infrastructure investment, at a cost measured in hundreds of millions of dollars. Is that feasible? The topline answer is yes. All three segments can be done in the specified amount of time. North of New Haven, there are generous margins, but 30-minute travel times will rely on electrifying the Shuttle and running high-quality electric trains. South of New Haven, each segment has just seconds to spare to achieve the governor’s goal, and no big-ticket capital investment would be needed, but the plan will require a complete overhaul in Metro-North operations.

Some additional repairs are needed on tracks straight enough to allow trains to run at 160 km/h, which are today only maintained to allow 75 mph, or 120 km/h. The state may also need to procure lighter trains, able to accelerate faster than the current equipment. On a fast schedule, with few intermediate stops, the difference with the current M8 trains is small, but in practice north of Stamford, where trains are likely to make many stops, the difference would be noticeable.

Most of all, reliability must improve enough that is possible to remove the extensive schedule padding in the timetable today. Metro-North is in a perpetual maintenance cycle. At any time there is a slow zone somewhere on the tracks, with generous schedule padding on top of it. Maintenance must be switched to the nighttime, as is practiced on high-speed lines in Japan and France and on subways everywhere in the world outside New York, in order to improve daytime reliability.

The simulation of train performance

In order to figure out the best possible trip times, I made a table of speed zones on the New Haven Line, from Grand Central to New Haven. But instead of using current speed zones, which are very conservative, I looked for the maximum speed that is feasible within the current right-of-way.

The most important rule I followed is no curve modifications, even modifications that are likely to happen under any high-speed rail scenario. While some capital investment may still be required, it is entirely within existing rights-of-way.

In the simulation, I used code outputting slow penalties for trains based on prescribed performance characteristics. For this, I used two sets of characteristics. The first, is for the M8 trains used by Metro-North today. The second is an average of modern European regional trains, such as the Stadler FLIRT, the Alstom Coradia, the Bombardier Talent 2, the CAF Civity, and the Siemens Mireo. Because they are much lighter-weight, all have about 50% better acceleration than the M8 at any speed. Both sets of trains can reach the same top speed, 160 km/h, but when the M8 slows down from top speed to make a station stop, the extra acceleration and deceleration time add another 69 seconds to the trip, compared with only 46 seconds on the European regional trains.

That said, the proposed schedule has few intermediate stops, and even with frequent slowdowns due to curves, the total difference in time between the two sets of trains is about two minutes. So, while I would urge Connecticut to buy modern trains at its next procurement, based on the latest revision in FRA regulations permitting lightly-modified European trains, the present-day rolling stock is good enough, it’s just much heavier than it needs to be.

While I did not assume any curve modifications, I did assume that trains could run faster on curves than they do today. The New Haven Line has conservative values for the permitted centrifugal force acting on trains. I explain more about this in a previous post about trains in Connecticut, but the relevant figures are about 8” of total equivalent cant on the New Haven Line today, or about 200 mm, whereas light trackwork increasing total cant and already-existing regulatory changes above the rails could raise this to 12” on existing trains, about 300 mm, and even more on tilting trains like the Acela. The difference between 200 and 300 mm of total equivalent cant corresponds to a 22% increase in speed; the formula is $\sqrt{1.5} = 1.22$.

Moreover, in some areas the maximum speeds are even lower than one might assume based on curve radius and current permitted curve speeds. These include the movable bridges over the waterways, which have very low speed limits even when the tracks are mostly straight; if the bridges physically cannot accommodate faster trains then they should be replaced, a capital investment already on the state and the region’s official wishlist.

In addition to speed limits imposed by curves and bridges, there is a uniform speed limit of 90 mph (145 km/h) on the New York segment of the line and 75 mph on the Connecticut segment. This is entirely a matter of poor maintenance: the right-of-way geometry could support higher speed today in some places, even without curve modifications.

Finally, trains today go at excruciatingly slow speed in the throat heading into the bumper tracks at Grand Central, 10 miles per hour. This is bad practice: even with bumper tracks, German train throats with complex switches are capable of 70 km/h. This change alone would save about 4 minutes. Overall, trains today are scheduled to take about 11-12 minutes between Grand Central and Harlem, and the proposed schedule cuts this down to 5-6.

The proposed schedule

I am attaching a spreadsheet with exact speed zones, rounded down in 5 km/h increments. People who wish to see what’s behind the timetable I’m proposing can go look there for intermediate times. These may be especially useful to people who want to see what happens if more stops on the Lower New Haven Line are included. For example, one might notice that all technical travel times are padded 7%, as is standard practice in Switzerland, and that trains dwell exactly 30 seconds at each station, which is observed on busy commuter lines in Zurich as well as Paris.

I am including two stopping patterns: regional and intercity. Regional trains make the same stops as the Upper New Haven Line trains do today, plus New Rochelle. Intercity trains only make a few stops beyond Stamford, with a stopping pattern close to that of Amtrak. In addition, I am including two different sets of rolling stock: the current M8, and lighter, faster-accelerating European trainsets. The difference in the regional train pattern is noticeable, while that in the intercity one is less so.

Finally, at stations, it’s possible to state the scheduled the time the train arrives at the station or the one it departs. At all intermediate stations, the timetable below states the arrival time, unlike the attached spreadsheet, which uses departure times to permit calculating exact average speeds.

 Stop Regional, M8 Regional, euro Intercity, M8 Intercity, euro Grand Central 0:00 0:00 0:00 0:00 Harlem-125th 0:05 0:05 0:05 0:05 New Rochelle 0:17 0:16 0:17 0:16 Stamford 0:30 0:29 0:30 0:29 Noroton Heights 0:34 0:33 Darien 0:37 0:35 Rowayton 0:39 0:37 South Norwalk 0:42 0:40 0:37 0:36 East Norwalk 0:45 0:42 Westport 0:48 0:45 Greens Farms 0:52 0:48 Southport 0:55 0:51 Fairfield 0:57 0:53 Fairfield Metro 1:00 0:56 Bridgeport 1:04 0:59 0:49 0:47 Stratford 1:09 1:03 Milford 1:13 1:07 West Haven 1:19 1:13 New Haven 1:23 1:17 1:03 1:01

New Haven-Hartford-Springfield

In theory, achieving the governor’s proposed timetable is easier north of New Haven. The Hartford Line is a straight route. Most of it has a top speed of 80 mph, and outside the approaches to New Haven and Hartford, the speed restrictions are caused by arbitrarily slowdowns for grade crossings rather than by constrained geometry.

However, in practice, the line is in poor state of repair. Grade crossings are unprotected. The entire line is not electrified, and there are no plans to electrify it, for reasons that can only be explained as an allergy that North American railroaders have to electrification. The stations have low platforms, which are not accessible to people in wheelchairs without labor-intensive, time-consuming lift operations—and even if there are no riders with disabilities, it just takes longer for passengers to board from low platforms.

The above schedule assumes 7% padding and 30-second dwell times at stations, but such assumptions only work when the equipment is reliable, and when there are wide doors letting passengers on the train with level boarding or at worst short steps. Traditional commuter lines pulled by diesel locomotives, serving low-platform stations with narrow doors, have to be much slower. Clem Tillier‘s example timetable for Caltrain requires 15% padding and 45-second dwell times with today’s diesel operations—and at rush hour some station dwells stretch over minutes due to the railroad’s uniquely high number of passengers with bicycles.

The good news is that electrification and high platforms are, in the grand scheme of things, cheap. Amtrak electrified the Northeast Corridor between New Haven and Boston at $3.5 million per kilometer in the 1990s, adjusted for inflation; at that cost, wiring the entire New Haven-Springfield shuttle would run up to$350 million. Moreover, Boston has been equipping a number of commuter rail stations with high platforms in order to provide wheelchair accessibility, and in ordinary circumstances, the costs have been on the order of $6-10 million per station. This entire package on the Hartford Line would be cheaper than replacing any of the movable bridges on the New Haven Line. Moreover, upgrading grade crossings with four-quadrant gates, which make it impossible for cars to drive around the gates while they are closed, is affordable as well—and would permit the towns along the route to institute quiet zones, eliminating the loud train horns. In Boulder, the same installation costs about$500,000 per grade crossing for quad gates and another $300,000 for an alternative to horns; in federal regulations, quad gates are good up to 110 mph. There are 23 level crossings between New Haven and Hartford and another 11 between Hartford and Springfield;$30 million would upgrade them all.

The importance of a good maintenance regime

In Switzerland, schedules are padded by 7% over the technical travel time, to permit trains to recover from delays. By American standards, this is a low figure: the LIRR’s schedules are padded by 20-30%, and I have personally seen an express New Haven Line train do Stamford-Grand Central in about 15% less than the scheduled trip time.

Switzerland achieves high punctuality with relatively tight scheduling by making sure delays do not propagate. Railroad junctions are grade-separated when possible, and if not then they are equipped with pocket tracks to allow trains to wait without delaying crossing traffic. To achieve comparable reliability, Metro-North should grade-separate its most important junctions: Shell, where the line joins with the Northeast Corridor tracks carrying Amtrak (and soon Penn Station Access); and Stam, where the New Canaan Branch joins. It could potentially also grade-separate Berk, where the Danbury Branch joins, and Devon, where the Waterbury Branch joins, but the traffic at these junctions is lighter and delayed branch trains can wait without disturbing mainline trains.

Moreover, like the rest of Europe as well as Japan, Switzerland conducts maintenance at night. The daytime maintenance with work zones that are a common sight on American passenger railroads are unknown on most European railroads. Only mixed lines running high-speed passenger trains in the day and freight at night have to schedule trains next to active work zones, and those are indeed much harder to maintain.

The laws of physics are the same on both sides of the Atlantic. If it’s possible to maintain tracks adequately during four-hour nighttime windows in Europe, it’s possible to do the same in the United States. Freight traffic on the Northeast Corridor is lighter than on many Swiss mainlines, and while passenger traffic at rush hour is very heavy, in the off-peak it is considerably lighter than on the urban commuter rail line trunks of Zurich. While four Metro-North trains run between New York and Stamford every off-peak hour, as does a single Amtrak train, ten Zurich S-Bahn trains run per hour between Zurich and Winterthur, as do six interregional and intercity trains.

The importance of maintenance was underscored in a recent article describing an independent plan to drastically cut travel times through better track standards, spearheaded by Joe McGee of the Business Council of Fairfield County and authored by San Francisco consultant Ty Lin and former Metro-North president Joseph Giulietti. In response to their plan, CDOT said it was not possible—and to emphasize this fact, the article notes that an upcoming schedule revision will slow down the trains by 6 to 10 minutes due to trackwork delays.

The one thing that the state must avoid is funneling any money into State of Good Repair (SOGR) programs. SOGR is a black hole permitting incompetent officials to spend capital money without anything to show for it: agencies around the country have SOGR programs decade after decade and somehow their stated maintenance backlogs never shrink.

Instead, 30-30-30 is the closest thing to a true program for what SOGR is supposed to be. Were the tracks in good shape, and were speeds on curves in line with modern railroading practices in other developed countries, express trains would take exactly half an hour to travel between Grand Central and Stamford and between Stamford and New Haven. So 30-30-30 is really setting a standard for a program that, up until now, has only served as an excuse for CDOT to do nothing.

It’s not yet clear what CDOT and Metro-North’s reaction to 30-30-30 will be. Is the governor’s goal achievable? Absolutely, give or take a few minutes. Is it achievable on a reasonable budget? Definitely. Are the managers who have let train schedules slip over the years, as their counterparts in New York have, capable of running the trains punctually enough in order to meet the timetable? That is the big question mark.

# Fix the Slowest Speed Zones

I am wrapping up a project to look at speedup possibilities for trains between New York and New Haven; I’ll post a full account soon, but the headline result is that express trains can get between Grand Central and New Haven in a little more than an hour on legacy track. In this calculation I looked at speed zones imposed by the curves on the line. The biggest possible speedups involve speed limits that are not geometric – and those in turn come from some very sharp slow zones. The worst is the Grand Central station throat, and I want to discuss that in particular since fixing the slowest zones usually yields the most benefits for train travel times.

Best practice for terminal approaches

Following Richard Mlynarik’s attempt to rescue the Downtown Extension in San Francisco, I’ve assumed that trains can approach terminals at 70 km/h, based on German standards. At this speed, an EMU on level track can stop in about 150 meters. In Paris, the excellent Carto Metro site details speed limits, and at most terminals with bumper tracks the speed limit is 60 km/h, with a few going up to 100 km/h.

Even with bumper tracks, 70 km/h can be supported, provided the train is not intended to stop right at the bumpers. At a fixed speed, the deceleration distance is the inverse of the deceleration rate. There is some variation in braking performance, but it’s in a fairly narrow range; on subway trains in New York, everything is supposed to brake at the same nominal rate of 3 mph/s, or 1.3 m/s^2, and when trains brake more slowly it’s because of a deliberate decision to avoid wearing the brakes out. As long as the train stops 1-2 car lengths away from the bumpers, as is routine on Metro-North, the variation will be much smaller than the margin of safety.

Fast movement through the station throat is critical for several reasons. First, as I’ll explain below, sharp speed limits have an outsize effect on trip times, and can be fixed without expensive curve easements or top-rate rolling stock. And second, at train stations with a limited number of tracks, the station throat is the real limiting factor to capacity, since trains would be moving in and out frequently, and if they move too slowly, they’ll conflict. With its 60 km/h throat, Saint-Lazare on the RER E turns 16 trains per hour at the peak on only four tracks.

American practice

I had a conversation with other members of TransitMatters in Boston yesterday, in which we discussed work to be done for our regional rail project. One of the other members, I forget who, asked me, do European train protection systems shut down in station throats too?

The answer to the question is so obviously yes that I wanted to understand why anyone would ask it. Apparently, the American mandate for automatic train protection on all passenger rail lines, under the name positive train control, or PTC, is only at speeds higher than 10 miles per hour. At 10 mph or less train operators can drive the train by sight, and no signaling is required, which is why occasionally trains overrun the bumpers even on PTC-equipped lines if the driver has sleep apnea.

Without video, nobody could see the facial expressions I was making. I believe my exact words were “…What? No! What? What the hell?”.

The conversation was about South Station, but the same situation occurs at Grand Central. Right-of-way geometry is good for decent station approach speed – there is practically no limit at Grand Central except tunnel clearances, which should be good for 100 km/h, and at South Station the sharp curve into the station from the west is still good for around 70 km/h given enough superelevation.

The impact of slow zones near stations

Last year, I published code for figuring out acceleration penalties based on prescribed train characteristics. The relevant parameters for Metro-North’s M8 is initial acceleration = 0.9 m/s^2, power/weight = 12 kW/t. Both of these figures are about two-thirds as high as what modern European EMUs are capable of, but it turns out that at low speed it does not matter too much.

Right now the Grand Central throat has a 10 mph speed limit starting just north of 59th Street, just south of milepoint 1. The total travel time over this stretch is 6 minutes, a familiar slog to every regular Metro-North rider; overall, the schedule between Grand Central and Harlem-125th Street is 10 minutes northbound and 12-13 minutes southbound, the difference coming from schedule padding. The remaining 65 or so blocks are taken at 60 mph, nearly 100 km/h, and take around 4 minutes.

Now, let’s eliminate the slow zone. Let trains keep cruising at 100 km/h until they hit the closer-in parts of the throat, say the last kilometer, where the interlocking grows in complexity and upgrading the switches may be difficult; in the last kilometer, let trains run at 70 km/h. The total travel time in the last mile now shrinks to a minute, and the total travel time between Grand Central and Harlem shrinks to 5 minutes and change. Passengers have gained 5 minutes based on literally the last mile.

For the same reason, the Baltimore and Potomac Tunnel imposes a serious speed limit – currently 30 mph through the tunnel, lasting about 2 miles; removing this limit would cut 2-2.5 minutes from the trip time, less than Grand Central’s 5 because the speed limit isn’t as wretched.

The total travel time between New York and New Haven on Metro-North today is about 1:50 off-peak, on trains making all stops north of Stamford. My proposed schedule has trains making the same stops plus New Rochelle doing the trip in 1:23. Out of the 27-28 minutes saved, 5 come from the Grand Central throat, the others coming from higher speed limits on the rest of the route as well as reduced schedule padding; lifting the blanket 75 mph speed limit in Connecticut is only worth about 3 minutes on a train making all stops north of Stamford, and even on an express train it’s only worth about 6 minutes over a 73 kilometer stretch.

What matters for high-speed travel

High-speed rail programs like to boast about their top speeds. But in reality, the difference between a vanilla 300 km/h train and a top of the line 360 km/h only adds up to a minute every 30 kilometers, exclusive of acceleration time. Increasing top speed is still worth it on lines with long stretches of full-speed travel, such as the Tohoku Shinkansen, where there are plans to run trains at 360 over hundreds of kilometers once the connection to Hokkaido reaches Sapporo. However, ultimately, all this extra spending on electricity and noise abatement only yields a second-order improvement to trip times.

In contrast, the slow segments offer tremendous opportunity if they are fixed. The 10 mph limit in the immediate Penn Station throat slows trains down by around 2 minutes, and those of Grand Central and South Station slow trains by more. A 130 km/h slog through suburbia where 200 km/h is possible costs a minute for every 6.2 km, which easily adds up to 5 minutes in a large city region like Tokyo. An individual switch that imposes an undue speed limit can meaningfully slow the schedule, which is why the HSR networks of the world invented high-speed turnouts.

Richard Mlynarik notes that in Germany, the fastest single end-to-end intercity rail line used to be Berlin-Hamburg, a legacy line limited to 230 km/h, where trains averaged about 190 km/h when Berlin Hauptbahnhof opened (they’ve since been slowed and now average 160). Trains go at full speed for the entire way between Berlin and Hamburg, whereas slow urban approaches reduce the average speed of nominally 300 km/h Frankfurt-Cologne to about 180, and numerous compromises reduce that of the nominally 300 km/h Berlin-Munich line to 160; even today, trains from Berlin to Hamburg are a hair faster than trains to Munich because the Berlin-Hamburg line’s speed is more consistent.

The same logic applies to all travel, and not just high-speed rail. The most important part of a regional railway to speed up is the slowest station throats, followed by slow urban approaches if they prove to be a problem. The most important part of a subway to speed up is individual slow zones at stations or sharp curves that are not properly superelevated. The most important part of a bus trip to speed up is the most congested city center segment.

# The Fish Rots from the Head

All reform agendas run into the same problem: someone needs to implement the reform, and this someone needs to be more politically powerful than the entrenched interests that need reform. The big political incentive for a leader is to swoop in to fix an organization that is broken and get accolades for finally making government work. But whether this work depends on what exactly is broken. If the fish rots from the tail, and better management can fix things, then reformist politicians have an easy time. The problem is that if the fish rots from the head – that is, if the problem is the political leaders themselves – then there is no higher manager that can remove underperforming workers. My contention is that when it comes to poor American public transit practices, the fish usually rots from the head.

Whither fixing construction costs?

I wrote my first comment documenting high New York construction costs at the end of 2009. By 2011 this turned into my first post in my series here with some extra numbers. By the time I jumped from commenting to blogging, the MTA had already made a reference to its high costs in a 2010 report called Making Every Dollar Count (p. 11): “tunneling for the expansion projects has cost between three and six times as much as similar projects in Germany, France and Italy.” New York City Comptroller Scott Stringer has been plagiarizing my 2011 post since 2013.

However, the early recognition has not led to any concrete action. There has not been any attention even from leaders who could gain a lot of political capital from being seen as fixing the problem, such as governors in California, New York, and Massachusetts, as well as successive New York mayors. That Governor Cuomo himself has paid little attention to the subway can be explained in terms of his unique personal background from a car-oriented city neighborhood, but when it’s multiple governors and mayors, it’s most likely a more systemic issue.

What’s more, there has been plenty of time to come up with an actionable agenda, and to see it pay dividends to help catapult the career of whichever politician can take credit. The MTA report came out 9 years ago. An ambitious, forward-thinking politician could have investigated the issue and come up with ways to reduce costs in this timeframe – and in the region alone, four politicians in the relevant timeframe (Mayors Bloomberg and de Blasio, Cuomo, and Governor Christie) had obvious presidential ambitions.

Evidently, there has been action whenever a political priority was threatened. The LIRR had long opposed Metro-North’s Penn Station Access project, on the grounds that by sending trains through a tunnel used by the LIRR, Metro-North would impinge on its turf. As it was a visible project and a priority for Cuomo, Cuomo had to remove the LIRR’s obstruction, and thus fired LIRR President Helena Williams in 2014.

So what’s notable is that construction costs did not become a similar political priority, even though rhetoric of government effectiveness and fighting waste is ubiquitous on the center-left, center, and center-right.

Who benefits?

That successive powerful American leaders have neglected to take on construction costs suggests that there is no benefit to them in fixing the problem. The question is, who benefits from high costs, then?

The answer cannot be that these politicians are all corrupt. The inefficiency in construction does not go to any serious politician’s pockets. Corruption might, but that requires me to believe that all relevant mayors and governors take bribes, which I wouldn’t believe of Italy, let alone the United States. One or two crooks could plausibly lead to cost explosion in one place, but it is not plausible that every serious politician in the New York area in the last decade has been both corrupt and in on the exact same grift.

Another answer I’d like to exclude is powerful interest groups. For example, if the main cause of high American construction costs were unions, then this would explain why governors all over the more liberal states don’t make an effort to build infrastructure more cheaply. However, there are enough high-cost states with right-wing politics and anti-union laws. The other entrenched interest groups are quite weak nationwide, for example planners, who politicians of all flavors love to deride as unelected bureaucrats.

The pattern of competence and incompetence

In my dealings with New York, I’ve noticed a pattern: the individual planners I talk to are curious, informed, and very sharp, and I don’t just mean the ones who leak confidential information to me. This does not stop at the lower levels: while most of my dealings with planners were with people who are my age or not much older, one of my sources speaks highly of their supervisor, and moreover my interactions with senior planners at the MTA when Eric Goldwyn and I pitched our bus redesign were positive. Eric also reports very good interactions with bus drivers and union officials.

In contrast, the communications staff is obstructive and dishonest. Moreover, the most senior layer of management is simply incompetent. Adam Rahbee describes it as “the higher up you get, the less reasonable people are” (my paraphrase, not a direct quote); he brings up work he proposed to do on reworking on the subway schedules, but the head of subway operations did not have the budget to hire an outside consultant and the higher-up managers did not even know that there was a problem with trains running slower than scheduled (“running time”).

A number of area observers have also noticed how MTA head Ronnie Hakim, a Cuomo appointee, was responsible to much of the recent spate of subway slowdowns. Hakim, with background in law rather than operations, insisted speed should not be a priority according to Dan Rivoli’s sources. The operations staff seem to hate her, judging by the number and breadth of anonymous sources naming her as one of several managers who are responsible for the problem.

The pattern is, then, that the put-upon public workers who run the trains day in, day out are fine. It’s the political appointees who are the problem. I don’t have nearly so many sources at other transit agencies, but what I have seen there, at least in Boston and San Francisco, is consistent with the same pattern.

Quite often, governors who aim to control cost institute general hiring freezes, via managers brought in from the outside, even if some crucial departments are understaffed. For example, Boston has an epidemic of bus bunching, is staffed with only 5-8 dispatchers at a given time, and can’t go up to the necessary 15 or so because of a hiring freeze. The 40 or so full-time dispatchers who are needed to make up the difference cost much less than the overtime for bus drivers coming from the bunching, to say nothing of the extra revenue the MBTA could get if, with the same resources, its buses ran more punctually. In the name of prudence and saving money, the MBTA wastes it.

The risk aversion pattern

The above section has two examples of political interference making operations worse: a hiring freeze at the MBTA (and also at the MTA), and Ronnie Hakim deemphasizing train speed out of fear of lawsuits. There is a third example, concerning capital planning: Cuomo’s interference with the L shutdown, well covered by local sources like Second Avenue Sagas, in which the governor effectively took sides in an internal dispute against majority opinion just because engineering professors in the minority had his ear. All three examples have a common thread: the negative political interference is in a more risk-averse direction – hiring fewer people, running slower trains, performing ongoing maintenance with kludges rather than a long-term shutdown.

The importance of risk-aversion is that some of the problems concerning American construction costs are about exactly that. Instead of forcing agencies that fight turf battles to make nice, political leaders build gratuitous extra infrastructure to keep them on separate turf, for example in California for high-speed rail. Only when these turf battles risk a visible project, such as the LIRR’s opposition to Penn Station Access, do the politicians act. Costs are not so visible, so politicians let them keep piling, using slush funds and raiding the rest of the budget.

In New York, the mined stations, too, are a problem of risk-aversion. Instead of opening up portions of Second Avenue for 18 months and putting it platforms, the MTA preferred to mine stations from a smaller dig, a five-year project that caused less street disruption over a longer period of time. An open dig would invite open political opposition from within the neighborhood; dragging it over five years may have caused even more disruption, but it was less obtrusive. The result: while the tunneling for Second Avenue Subway was about twice as expensive as in Paris, the stations were each seven times as expensive. The overall multiplier is a factor of seven because overheads were 11 times as expensive, and because the stop spacing on Second Avenue is a bit narrower than on the Paris Metro extension I’m comparing it with.

In contrast with the current situation in New York, what I keep proposing is politically risky. It involves expanding public hiring, not on a massive level, but on a level noticeable enough that if one worker underperforms, it could turn into a minor political scandal in which people complain about big government. It involves promoting smart insiders as well as hiring smart outsiders – and those outsiders should have industry experience, like Andy Byford at New York City Transit today, not political experience, like the MBTA’s Luis Ramirez or the FRA’s Sarah Feinberg; by itself, hiring such people is not risky, but giving them more latitude to operate is, as Cuomo discovered when Byford began proposing his own agenda for subway investment.

On the engineering level, it involves more obtrusive construction: tunnels and els, not bus lanes that are compromised to death – and the tunnels may involve cut-and-cover at stations to save money. Regional rail is obtrusive politically, as modernization probably requires removal of many long-time managers who are used to the current way of doing things (in Toronto, the engineers at GO Transit obstructed the RER program, which was imposed from Metrolinx), and in New York the elimination of Long Island and the northern suburbs’ respective feudal ownership of the LIRR and Metro-North. The end result saves money, but little kings of hills will object and even though American states have the power to overrule them, they don’t want the controversy.

The fish rots from the head

American transportation infrastructure does not work, and is getting worse. The costs of building more of it are extremely high, and seem to increase with every construction cycle. Operating costs for public transit run the gamut, but in the most important transit city, New York, they are the highest among large world cities, and moreover, the cheapest option for extending high-quality public transit to the suburbs, regional rail, is not pursued except in Silicon Valley and even there it’s a half-measure.

The problems are political. Heavyweight politicians could use their power to force positive reforms, but in a number of states where they’ve been able to do so on favorable terms, they’ve done no such thing. On the contrary, political influence has been negative, installing incompetent or dishonest managers and refusing to deal with serious long-term problems with operations and maintenance.

The reason politicians are obstructive is not that there’s no gain in improving the state of public services. On the contrary, there is a huge potential upside to getting credit for eliminating waste, fraud, and abuse and delivering government projects for much cheaper than was thought possible. But they look at minor controversies that could come from bypassing local power brokers, who as a rule have a fraction of the influence of a governor or big city mayor, or from building bigger projects than the minimum necessary to be able to put their names or something, and stop there.

One animal analogy for this is that the fish rots from the head: the worst abuses come from the top, where politicians prefer slow degradation of public services to a big change that is likely to succeed but risks embarrassment or scandal. The other animal analogy is that, through a system that rewards people who talk big and act small, American politics creates a series of chickenshit leaders.

# Where Line 2 Should Go Depends on Where Line 1 Goes

A city that is building a rapid transit network piecemeal has to decide on priorities. There are tools for deciding where to build the first line, such as looking at the surface transit network and seeing what the busiest corridor is. These are relatively well-understood. In this post I’d like to focus on where to build the second line, because that question depends not only on the usual factors for where to build transit, but also on how the first line is expected to change the network. This is relevant not only to cities that are building a new rapid transit system, but also to cities that have such a network and are adding new lines one at a time: the usual tools can straightforwardly suggest where to build one line, but figuring out where to build a second line requires some additional work.

A toy model

Consider the following city, with its five busiest buses, labeled A-E from busiest to fifth busiest:

Let’s stipulate that there’s a wealth of arterial roads radiating in the right directions, and no motorways entering city center, so the exceptions to the rule that trains should go where the busiest buses are don’t apply. Let’s also stipulate that the other buses in the city don’t affect the internal ranking of the first five much – so if there are a bunch of north-south buses close to route C not depicted on the map, they’re not busy enough to make it busier than route A.

Clearly, based on the A > B > C > D > E ranking, the top priority for a first rapid transit line is A. Not only is it the busiest bus but also it is parallel to the second busiest.

But the second priority is not B, but C. The reason is that a rapid transit line on A captures east-west traffic, and then from the eastern and western neighborhoods people on route B are likely to walk south or ride a circumferential bus to get to the train. In the presence of a subway underneath the arterial carrying route A, the strongest bus corridor will almost certainly become C, and thus planners should aim to build a subway there as their second line, and begin design even before the first subway opens.

Fourth Avenue in Vancouver

Vancouver already has a rapid transit system, with three SkyTrain lines. However, the issue of the second line crops up when looking at remaining bus corridors and future subway plans. The strongest bus route is by far Broadway, which had higher ridership than the buses that became the Millennium and Canada Lines even when those lines were planned. The Millennium Line was only built first because it was easier, as it is elevated through the suburbs, and the Canada Line because Richmond demanded a SkyTrain connection.

Fortunately, Broadway is finally getting a subway, running from the Millennium Line’s current terminus at VCC-Clark to Arbutus, halfway toward the corridor’s natural end at UBC. The question is, what next? The second busiest bus corridor in Vancouver is Fourth Avenue, where the combined ridership of the 4, 44, and 84 buses and the part of the 7 that is on Fourth exceeds that of any corridor except Broadway; only Hastings, hosting the 95 and 160, comes close.

And yet, it is obviously wrong to plan any subway on Fourth Avenue. Fourth is half a kilometer away from Broadway; the 44 and 84 are relief for the 99 on Broadway. TransLink understands it and therefore there are no plans to do anything on Fourth – the next priority is extending the Expo Line farther out into Surrey or Langley, with the exact route to be determined based on political considerations.

Regional rail and subways in New York

In New York, two commonly-proposed subway extensions, down Nostrand and Utica, are closely parallel. The fact that they are so close to each other means that if one is built, the case for the other weakens. But these two corridors are so strong it is likely that if one is built, the second remains a very high priority. The only subway priority that is plausibly lower than the first of the two and higher than the second, regardless of which of Utica and Nostrand is built first, is a 125th Street crosstown extension of Second Avenue Subway.

But a more serious example of one future line weakening another occurs for regional rail. The top priority for regional rail in New York is four-tracking the tunnels to Penn Station under the Hudson; based on this priority, organizations that look beyond the next gubernatorial or congressional election have come up with farther-reaching proposals. Here, for example, is the map from the RPA’s Fourth Regional Plan:

In addition to four-tracking the North River Tunnels under the aegis of the Gateway project, the RPA calls for two additional two-track tunnels under the Hudson, in phases 2 and 3 of its proposal. Both are to feed Midtown: the phase 2 tunnel is to connect regional rail lines to be reactivated with Columbus Circle, Grand Central, and other destinations in the city, and the phase 3 tunnel is to then carry the same line out of the city and back into New Jersey via Hoboken and the existing commuter lines serving southern and southwestern suburbs.

The logic, as I understand it, is that Midtown is the core of the New York region, and so it is the most important to connect there. I don’t know if this is what the RPA was thinking, but I asked at an IRUM meeting in 2010 why all plans involve connections to Midtown rather than Lower Manhattan and was told Lower Manhattan was not as important a business district.

The toy model has one fixed city center and varying outlying areas, the opposite of the situation here. Here, my criticism is of plans that serve the dominant city center while ignoring the second most important center. The total number of jobs in Midtown is 800,000 whereas Lower Manhattan has 250,000 – but Lower Manhattan is more compact, so a single station at Fulton with several exits can plausibly serve the entire area, whereas Midtown has areas that are too far from both Penn Station and Grand Central. The next pair of tracks should serve Midtown, but the pair after them should serve Lower Manhattan, to ensure good coverage to both business districts.

# Difficult Urban Geography Part 1: Narrow Streets

I did a complex Patreon poll about series to write about. People voted for general transit network design, and more posts about national traditions of transit in the mold of the one about the US. Then I polled options for transit network design. There were six options, and people could vote up or down on any. Difficult urban geography was by far the most wanted, and three more alternatives hover at the 50% mark. To give the winning option its due course, I’m making it a mini-series of its own.

There are cities that, due to their street layout, make it easy to run transit on them. Maybe they are flat and have rivers that are easy to bridge or tunnel under. Maybe they have a wealth of wide arterials serving the center, with major cross streets at exactly the right places for stations and an underlying bus grid. Maybe they spread out evenly from the center so that it’s easy to run symmetric lines. Maybe their legacy mainline rail network is such that it’s easy to run interpolating buses and urban rail lines.

And then there are cities that are the exact opposite. In this post I’m going to focus on narrow or winding streets and what they mean for both surface and rapid transit. The good fortune for transit planners is that the city that invented urban rapid transit, London, is a prime example of difficult urban geography, so railway engineers have had to deal with this question for about 150 years, inventing some of the necessary technology in the process.

Rapid transit with narrow streets

The easiest ways to build rapid transit are to put it on a viaduct and to bury it using cut-and-cover tunneling. Both have a minimum street width for the right-of-way – an el requires about 10 meters, but will permanently darken the street if it is not much wider, and a tunnel requires about 10 meters for the tracks but closer to 18 for the stations.

Nonetheless, even cities with narrow streets tend to have enough streets of the required width. What they don’t always have is streets of the required width that are straight and form coherent spines. The labyrinth that is Central London does have wide enough streets for cut-and-cover, but they are not continuous and often miss key destinations such as major train stations. The Metropolitan line could tunnel under Euston Road, but the road’s natural continuation into the City is not so wide, forcing the line to carve a trench into Farringdon. Likewise, the District line could tunnel under Brompton Road or King’s Road, but serving Victoria and then Westminster would have required some sharp curves, so the District Railway carved a right-of-way, demolishing expensive Kensington buildings at great expense.

While London is the ur-example, as the city that invented the subway, this situation is common in other cities with large premodern cores, such as Rome, Milan, and Istanbul. Paris only avoided this problem because of Haussmann’s destruction of much of the historic city, carving new boulevards for aesthetics and sewer installation, which bequeathed the Third Republic a capital rich in wide streets for Metro construction.

Dealing with this problem requires one of several solutions, none great:

Deep-bore tunneling

London’s solution was to invent the tunnel boring machine to dig deep Tube lines, avoiding surface street disruption. With electric-powered trains and reliable enough TBMs to bore holes without cave-ins, London opened the Northern line in 1890, crossing the Thames to provide rapid transit service to South London. Subsequently, London has built nearly all Underground lines bored, even in suburban areas where it could have used cut-and-cover.

The main advantage to TBMs is that they avoid surface disruption entirely. Most first-world cities use them to bore tunnels between stations, only building stations cut-and-cover. The problem is that TBMs are more expensive to use than cut-and-cover today. While turn-of-the-century London built Tube lines for about the same cost per km as the Metropolitan line and as the cut-and-cover Paris Metro and New York City Subway, in the last half century or so the cost of boring has risen faster than that of shallow construction.

The worst is when the stations have to be mined as well. Mining stations has led to cost blowouts in New York (where it was gone gratuitously) and on London Crossrail (where it is unavoidable as the tunnel passes under the older Underground network). A city that cannot use cut-and-cover tunnels needs to figure out station locations that are easily accessible for vertical digging.

The alternative is the large-diameter TBM. Barcelona is using this technique for Line 9/10, which passes under the older lines; the city has a grid of wide boulevards, but the line would still have to pass under the older metro network, forcing the most difficult parts to be deep underground. The large-diameter TBM reduces the extent of construction outside the TBM to just an elevator bank, which can be dug in a separate vertical TBM; if higher capacity is desired, it’s harder but still possible to dig slant bores for escalators. The problem is that this raises construction costs, making it a least bad solution rather than a good one; Barcelona L9, cheap by most global standards, is still expensive by Spanish ones.

Carving new streets

Before the 1880s, London could not bore the Underground, because the steam-powered trains would need to be close to surface for ventilation. Both the Metropolitan and District lines required carving new right-of-way when streets did not exist; arguably, the entire District line was built this way, as its inner segment was built simultaneously with the Victoria Embankment, under which it runs. The same issue happened in New York in the 1910s and again in the 1920s: while most of the city is replete with straight, wide throughfares, Greenwich Village is not, which forced the 1/2/3 to carve what is now Seventh Avenue South and later the A/C/E to carve the southern portions of Sixth Avenue.

This solution is useful mostly when there are wide streets with absolutely nothing between them that a subway could use. The reason is that demolishing buildings is expensive, except in very poor or peripheral areas, and usually rapid transit has to run to a CBD to be viable. If the entire route is hard to dig, a TBM is a better solution, but if there are brief narrows, carving new streets New York did could be useful, especially if paired with improvements in surface transit.

Looking for station sites

Milan built its first metro lines cut-and-cover. However, lacking wide streets, it had to modify the method for use in a constrained environment. Instead of digging the entire street at a sloped angle and only then adding retaining walls, Milan had to dig the retaining walls first, allowing it to dig up streets not much wider than two tracks side by side. This method proved inexpensive: if I understand this article right, the cost was 30 billion lire in 1957-1964 prices, which is €423 million in 2018 prices, or €35 million per km. Milan’s subsequent construction costs have remained low, even with the use of a TBM for Metro Line 5.

The problem with this method is that, while it permits digging tunnels under narrow medieval streets, it does not permit digging stations under the same streets. Milan is fortunate that its historical center is rich in piazzas, which offer space for bigger digs. One can check on a satellite map that every station on Lines 1 and 2 in city center is at a piazza or under a wide street segment; lacking the same access to easy station sites, Line 3 had to be built deeper, with tracks stacked one under the other to save space.

I have argued in comments that Paris could have used this trick of looking for less constrained sites for stations when it built Metro Line 1, permitting four tracks as in New York as long as the express stations under Rue de Rivoli stuck to major squares like Chatelet. However, Paris, too, is rich in squares, it just happens to be equally rich in wide streets so that it did not need to use the Milan method. London is not so fortunate – its only equivalent of Milan’s piazzas is small gardens away from major streets. It could never have built the Central line using the Milan method, and even the Piccadilly line, which partly passes under wide streets, would have been doubtful.

Surface transit

Rapid transit benefits from being able to modify the shape of the street network to suit its needs. Surface transit in theory could do the same, running in short tunnels or widening streets as necessary, but the value of surface modes is not enough to justify the capital expense and disruption. Thus, planners must take the street network as it is given. The ideal surface transit route runs in the street median on two dedicated lanes, with boarding islands at stops; creating a parking lane, a moving lane, and a transit lane in each direction on a street plus some allowance for sidewalks requires about 30 meters of street width or not much less. Below 25, compromises are unavoidable.

Cutting car lanes

A lane is about 3 meters wide, so removing the parking lanes reduces the minimum required street width by about 6 meters. Contraflow lanes instead allow the street to have the same four lanes, but with a moving lane and a parking lane in one direction only. In extreme cases it’s possible to get rid of the cars entirely; a transit mall is viable down to maybe 12-15 meters of street width. The problem is that deliveries get complicated if the city doesn’t have alleyways or good side street access, and this may force compromises on hours of service (perhaps transit doesn’t get dedicated lanes all day) or at least one parking lane in one direction.

Single-track streetcars

Some city cores with very narrow streets don’t have double-track streetcars. A few have one-way pairs, but more common is single-track segments, or segments with two overlapping tracks so that no switching is needed but trams still can’t pass each other. Needless to say, single-tracking is only viable over short narrows between wider streets, and only when the network is punctual enough that trams can be scheduled not to conflict.

On longer stretches without enough room for two tracks or two lanes, one-way pairs are unavoidable; these complicate the network, and unless the streets the two directions of the bus or tram run on are very close to each other they also complicate interchanges between routes. New York has many one-way pairs on its bus network, even on wide and medium-width streets in order to improve the flow of car traffic, and as a result, some crosstown routes, such as the B35 on Church, are forced to stop every 250 meters even when running limited-stop. While New York’s network complexity is the result of bad priorities and can be reversed, cities with premodern street networks may not even have consistent one-way pairs with two parallel streets on a grid; New York itself has such a network in Lower Manhattan.

Bus network redesign

The best way to avoid the pain associated with running buses on streets that are not designed for fast all-mode travel is not to run buses on such streets. Boston has very little surface transit in city center, making passengers transfer to the subway. In Barcelona, part of the impetus for Nova Xarxa was removing buses from the historic core with its narrow streets and traffic congestion and instead running them on the grid of the Eixample, where they would not only provide a frequent system with easy transfers but also run faster than the old radial network.

However, this runs into two snags. First, there must be some radial rapid transit network to make people connect to. Boston and Barcelona both have such networks, but not all cities do; Jerusalem doesn’t (it has light rail but it runs on the surface). And second, while most cities with a mixture of wide and narrow streets confine their narrow streets to premodern historic cores, some cities have streets too narrow for comfortable bus lanes even far out, for example Los Angeles, whose north-south arterials through the Westside are on the narrow side.

What not to do: shared lanes

It’s tempting for a transit agency to compromise on dedicated lanes whenever the street is too narrow to feature them while maintaining sufficient auto access. This is never a good idea, except in outlying areas with little traffic. The reason is that narrow streets fed by wide streets are precisely where there is the most congestion, and thus where the value of dedicated transit lanes is the highest.

In New York, the dedicated bus lanes installed for select bus service have sped up bus traffic by around 30 seconds per kilometer on all routes Eric Goldwyn and I have checked for our Brooklyn bus redesign project, but all of these figures are averaged over long streets. Within a given corridor, the short narrows that the transit agency decides to compromise on may well feature greater time savings from dedicated lanes than the long arterial stretch where it does set up dedicated lanes. This is almost certainly the case for the Silver Line in Boston, which has unenforced dedicated lanes most of the way on Washington Streets but then uses shared lanes through Downtown Boston, where streets are too narrow for dedicated lanes without reducing auto access.

# In-Motion Charging

While electric cars remain a niche technology, electric buses are surging. Some are battery-electric (this is popular in China, and some North American agencies are also buying into this technology), but in Europe what’s growing is in-motion charging, or IMC. This is a hybrid of a trolleybus and a battery-electric bus (BEB): the bus runs under wire, but has enough battery to operate off-wire for a little while, and in addition has some mechanism to let the bus recharge during the portion of its trip that is electrified.

One vendor, Kiepe, lists recent orders. Esslingen is listed as having 10 km of off-wire capability and Geneva (from 2012) as having 7. Luzern recently bought double-articulated Kiepe buses with 5 km of off-wire range, and Linz bought buses with no range specified but of the same size and battery capacity as Luzern’s. Iveco does not specify what its range is, but says its buses can run on a route that’s 25-40% unwired.

Transit planning should be sensitive to new technology in order to best integrate equipment, infrastructure, and schedule. Usually this triangle is used for rail planning, but there’s every reason to also apply it to buses as appropriate. This has a particular implication to cities that already have large trolleybus networks, like Vancouver, but also to cities that do not. IMC works better in some geographies than others; where it works, it is beneficial for cities to add wire as appropriate for the deployment of IMC buses.

Vancouver: what to do when you’re already wired

Alert reader and blog supporter Alexander Rapp made a map of all trolleybus routes in North America. They run in eight cities: Boston, Philadelphia, Dayton, San Francisco, Seattle, Vancouver, Mexico City, Guadalajara.

Vancouver’s case is the most instructive, because, like other cities in North America, it runs both local and rapid buses on its trunk routes. The locals stop every about 200 meters, the rapids every kilometer. Because conventional trolleybuses cannot overtake other trolleybuses, the rapids run on diesel even on wired routes, including Broadway (99), 4th Avenue (44, 84), and Hastings (95, 160), which are in order the three strongest bus corridors in the area. Broadway has so much ridership that TransLink is beginning to dig a subway under its eastern half; however, the opening of the Broadway subway will not obviate the need for rapid buses, as it will create extreme demand for nonstop buses from the western end of the subway at Arbutus to the western end of the corridor at UBC.

IMC is a promising technology for Vancouver, then, because TransLink can buy such buses and then use their off-wire capability to overtake locals. Moreover, on 4th Avenue the locals and rapids take slightly different routes from the western margin of the city proper to campus center, so IMC can be used to let the 44 and 84 reach UBC on their current route off-wire. UBC has two separate bus loops, one for trolleys and one for diesel buses, and depending on capacity IMC buses could use either.

On Hastings the situation is more delicate. The 95 is not 25-40% unwired, but about 60% unwired – and, moreover, the unwired segment includes a steep mountain climb toward SFU campus. The climb is an attractive target for electrification because of the heavy energy consumption involved in going uphill: at 4 km, not electrifying it would brush up against the limit of Kiepe’s off-wire range, and may well exceed it given the terrain. In contrast, the 5 km in between the existing wire and the hill are mostly flat, affording the bus a good opportunity to use its battery.

In a city without wires, IMC is the most useful when relatively small electrification projects can impact a large swath of bus routes. This, in turn, is most useful when one trunk splits into many branches. Iveco’s requirement that 60-75% of the route run under wire throws a snag, since it’s much more common to find trunks consisting of a short proportion of each bus route than ones consisting of a majority of route-length. Nonetheless, several instructive examples exist.

In Boston, the buses serving Dorchester, Mattapan, and Roxbury have the opportunity to converge to a single trunk on Washington Street, currently hosting the Silver Line. Some of these buses furthermore run on Warren Street farther south, including the 14, 19, 23, and 28, the latter two ranking among the MBTA’s top bus routes. The area has poor air quality and high rates of asthma, making electrification especially attractive.

Setting up wire on Washington and Warren Streets and running the Silver Live as open BRT, branching to the south, would create a perfect opportunity for IMC. On the 28 the off-wire length would be about 4.5 km each way, at the limit of Kiepe’s capability, and on the 19 and 23 it would be shorter; the 14 would be too long, but is a weaker, less frequent route. If the present-day service pattern is desired, the MBTA could still electrify to the northern terminus of these routes at Ruggles, but it would miss an opportunity to run smoother bus service.

In New York, there are examples of trunk-and-branch bus routes in Brooklyn and Queens. The present-day Brooklyn bus network has a long interlined segment on lower Fulton, carrying not just the B25 on Fulton but also the B26 on Halsey and B52 on Gates, and while Eric Goldwyn’s and my plan eliminates the B25, it keeps the other two. The snag is that the proportion of the system under wire is too short, and the B26 has too long of a tail (but the B52 and B25 don’t). The B26 could get wire near its outer terminal, purposely extended to the bus depot; as bus depots tend to be polluted, wire there is especially useful.

More New York examples are in Queens. Main Street and the Kissena-Parsons corridor, both connecting Flushing with Jamaica, are extremely strong, interlining multiple buses. Electrifying these two routes and letting buses run off-wire on tails to the north, reaching College Point and perhaps the Bronx on the Q44 with additional wiring, would improve service connecting two of Queens’ job centers. Moreover, beyond Jamaica, we see another strong trunk on Brewer Boulevard, and perhaps another on Merrick (interlining with Long Island’s NICE bus).

Finally, Providence has an example of extensive interlining to the north, on North Main and Charles, including various 5x routes (the map is hard to read, but there are several routes just west of the Rapid to the north).

IMC and grids

The examples in New York, Providence, and Boston are, not coincidentally, ungridded. This is because IMC interacts poorly with grids, and it is perhaps not a coincidence that the part of the world where it’s being adopted the most has ungridded street networks. A bus grid involves little to no interlining: there are north-south and east-west arterials, each carrying a bus. The bus networks of Toronto, Chicago, and Los Angeles have too little interlining for IMC to be as cost-effective as in New York or Boston.

In gridded cities, IMC is a solution mainly if there are problematic segments, in either direction. If there’s a historic core where wires would have adverse visual impact, it can be left unwired. If there’s a steep segment with high electricity consumption, it should be wired preferentially, since the cost of electrification does not depend on the street’s gradient.

Overall, this technology can be incorporated into cities’ bus design. Grids are still solid when appropriate, but in ungridded cities, trunks with branches are especially attractive, since a small amount of wire can convert an entire swath of the city into pollution-free bus operation.

# New York City Subway Expansion Proposal

I wrote a post proposing disentangling the subway in New York a few months ago. On the same basis, I’ve drawn some extra lines that I think should be built in the event the region can get its construction costs under control:

A higher-resolution image (warning: 52 MB) can be found here. The background image is taken from OpenStreetMap. Python 2.7 code for automatically downloading tiles and pasting them into a single image can be found here. Make sure you get PIL or else the paste.py file won’t run; first run tiles.py, and choose whichever tiles you’d like (the boundaries I used for this image are given in the paste.py code as x1, x2, y1, y2), and then run paste.py, changing the x1, x2, y1, y2 variables in the code as needed. As a warning, pasting images together makes them much bigger – the sum of the individual tiles I used is 15 MB but pasted together they became 46 MB.

Legend

Local stations are denoted by black circles, express stations by bigger circles with white filling. On four-track lines and three-track lines with peak-direction express trains (that is, the 2, 6, and D in the Bronx and the 7 in Queens), the local/express designation is straightforward. Two-track tails are denoted as all local; for the most part the trains continue as express on the three- or four-track lines, but on the Brighton Line the expresses keep turning at Brighton Beach while the locals are the trains that go into Coney Island. On a few two-track segments stations are denotes as express and not local, for example the 2 in Harlem or the A in Lower Manhattan and Downtown Brooklyn: this occurs when a two-track line turns into a three- or four-track line farther out, so that people don’t get the impression that these are local-only stations that the express trains skip.

The local and express patterns are barely changed from today. On Eastern Parkway trains run local east of Franklin Avenue, without skipping Nostrand and Kingston-Throop as the 4 does today. Skip-stop on the J train is eliminated, as is express-running between Myrtle and Marcy Avenues. On Queens Boulevard and Central Park West, the trains serving Sixth Avenue (i.e. the orange ones) run express and the ones serving Eighth (i.e. the blue ones) run local, but I’m willing to change my mind on at least one of these two designations; on Queens Boulevard, 36th Street is also turned into an express station, so that passengers can transfer to 63rd or 53rd Street.

As far as possible, I’ve tried to be clear about which stations are connected and which aren’t. The rule is that circles that touch or are connected by a black line denote transfer stations. However, in the lower-resolution version it may hinge on a single pixel’s worth of separation in Downtown Manhattan. The only new interchanges in Downtown Manhattan connect the 1 with PATH in the Village and at World Trade Center (and the latter connection also connects to the R, E, and 2/3).

No existing subway station is slated for closure. If an existing subway station is missing a circle, it’s an error on my part. Edit: I found one mistaken deletion – the 9th Street PATH station (which should be connected with West 4th, but the West 4th circle doesn’t touch PATH).

New lines

Most of this map should be familiar to people who have followed discussions among railfans in New York (and not just myself) about the next priorities after Second Avenue Subway. Utica and Nostrand are there, with stops that match nearly all of the east-west buses. Northern Boulevard, which Yonah Freemark pointed is a denser corridor than Utica, is also there. Triboro RX is there: the route through the Bronx includes a little more tunneling to connect with the 2 train better, forced by incursions onto the right-of-way farther north. LaGuardia gets an elevated extension of the N, which I’ve periodically argued is superior to other alignments and sound in its own right. Second Avenue Subway continues west under 125th Street, providing crosstown service on a street where buses are very busy despite being slower than walking.

In New Jersey, a hefty proportion of the lines already exist, as part of PATH or the Hudson-Bergen Light Rail. PATH is completely dismembered in this proposal: the line from Newark to World Trade Center is connected with the 6 train, an idea that I don’t think is a top priority but that some area advocates (such as IRUM) have proposed; most of the rest is turned into a 7 extension and connected with the two southern HBLR branches, both of which are extended, one to Staten Island and one to Newark; what remains is reduced to a shuttle from Hoboken to Sixth Avenue. Note that the 6-PATH train also gets an infill stop at Manhattan Transfer for regional rail connections.

The other extensions come from a number of different places:

• The 6 is extended to Co-op City, the 7 is extended to College Point, and the 1 to the edge of the city. The first two are big ridership generators, and all three also extend lines beyond their bumper tracks, increasing turnback capacity.
• The Queens Boulevard express trains branch in Jamaica, as they do today, and both branches are extended to near city limits. The southern extension also increases turnback capacity (some E trains run to Jamaica-179th and not Jamaica Center today for this reason), but the primary purpose is to improve coverage to areas of the city that are already at worst missing middle density and redevelopable as mid-rise apartment blocks, and have very long commutes today.
• The 1 is extended to Red Hook. This was proposed by AECOM a few years ago; my alignment differs somewhat in that it doesn’t connect Red Hook with the subway within Brooklyn, but does connect it directly with South Brooklyn, where in the event of such a subway extension a high-frequency bus (the B71) could run onward.
• Instead of the periodically mooted 7 extension to Secaucus, the L is extended there, with a four-track tunnel under the Hudson providing for easy 7/L transfers.
• There’s a preexisting bellmouth for connecting the C train to New Jersey across the George Washington Bridge; it is activated in this plan, with an extension to Paterson elevated over Route 4, with tunneling within Paterson itself. Route 4 is a freeway, but it’s flanked by shopping centers in Paramus, has good regional rail connections and good potential connections if the Northern Branch and West Shore Line are reactivated, and terminates in a dense working-class city.
• The old Erie Main Line gets converted to subway operations, running elevated through the built-up area of Secaucus.
• To connect some of the new lines to one another, two new Manhattan trunk lines, both two-track, are built: under 50th Street, and under Third Avenue, the latter substituting for phases 3 and 4 of Second Avenue Subway in order to avoid reverse-branching. Third then connects to the northern reaches of Eighth Avenue Line via a super-express line, with new stations at 110th and 125th; the alignment through Central Park is designed to allow cheap cut-and-cover construction.
• Bergenline Avenue, where traffic fills a bus every 2 minutes, gets a subway. One station is designed for a commuter rail transfer to new Hudson tunnels with a Bergenline stop. The segment south of Journal Square is weaker and can be removed from scope, but as it can be done in an existing above-ground right-of-way, it’s also cheaper than the rest.
• The D train gets a two-stop extension to the north to connect to Metro-North at Williams Bridge and the 2 train at Gun Hill Road.

Conspicuous absences

There is no subway connection to JFK or Newark Airport on this map. The JFK AirTrain is adequate with better regional rail and fare integration; so is a Newark connection at the current commuter rail station. A direct JFK regional rail connection may be included in a 9-line regional rail map (for reference, the map I usually peddle has 5 or 6 trunk lines, not 9). A Newark rapid transit connection may be included in a much more expansive version, but even then it’s unlikely – the only reason to build such a connection is for extra capacity, and it’s better to resolve mainline rail capacity crunches by building more mainline rail.

There is no R train to Staten Island, an extension that some railfans (including myself many years ago) periodically call for; this could be added, but is a low priority, as regional rail could provide faster service to Downtown Brooklyn with a transfer than the R train ever could.

But the biggest absence is Second Avenue Subway phases 3 and 4. Phase 3 is replaced with a subway under Third Avenue, and phase 4 is omitted entirely. The reason for this omission is, as mentioned above, to avoid reverse-branching, and permit the new system to consist of separate lines without track-sharing, which is more reliable than today’s heavily interlined system.

Phase 4 is also difficult and not all that useful. Lower Manhattan construction is sometimes necessary but should be avoided when it isn’t, as the area has narrow rights-of-way, complex underground station footprints, and archeology going back to the 17th century. There is no capacity crunch heading to Lower Manhattan – southbound trains unload in Midtown in the morning peak – and the area is so small and has so many subways that there is no coverage gap that Second Avenue Subway would fill. Even phase 3 mostly duplicates the Lexington Avenue Line, but serves a large and growing business district in East Midtown where trains do have a capacity crunch, hence the Third Avenue subway.

Scope and costs

The map has around 110 km of new subway and 100 km of new els and other open-air lines (such as the Triboro and Erie rights-of-way). Some of the subways can be built cut-and-cover given sufficient political cajoling, including Nostrand, most of Bergenline, parts of Third and Utica, Northern, and the outer Queens extension. But many cannot: there are 6 new river crossings (50th*2, 7, L, Utica, 1), a kilometer of pure pain in connecting the 6 with PATH, another PATH pain involving a new Exchange Place dig for platforms for the 7, and some new stations that have to be mined (e.g. 50th Street).

At what I consider a normal first-world cost, the tunnels would be around $25 billion in last decade’s money, so maybe$30 billion in today’s money, and the els would add around $10 billion. To put things in perspective, the current five-year MTA capital program is spending$33 billion, nearly all of which is routine maintenance. It’s affordable within a decade if the region gets its construction costs under control.

# The American Way of Building Rapid Transit

I’ve sporadically discussed how some countries or regions have traditions of how to build rapid transit. For example, in a City Metric article last year I made an off-hand comment about how communist bloc metros, from Europe to North Korea, have widely-spaced stops just like Moscow, while French metros and French-influenced Montreal Metro have short stop spacing just like Paris. I intend to write some posts covering different traditions, starting from one I’ve barely discussed as such: the American one. There are commonalities to how different American cities that build subways choose to do so, usually with notable New York influences, and these in turn affect how American transit activists think about trains.

For the most part, the American tradition of rapid transit should be viewed as one more set of standards, with some aspects that are worth emulating and others that are not. Most of the problems I’ve harped on are a matter of implementation more than a matter of standards. That said, that something is the local tradition does not immediately mean it works, even if on the whole the tradition is not bad. Some of the traditions discussed below definitely increase construction costs or reduce system effectiveness.

The situation in New York

A large majority of American rapid transit ridership, about two thirds, is in New York. The city’s shadow is so long that the systems built in the postwar era, like the Washington Metro and BART, were designed with New York as a reference, whether consciously or not. Only the Boston subway and Chicago L are old enough to avoid its influence – but then their elevated system design still has strong parallels in New York, whether due to direct influence or a common zeitgeist at the end of the 19th century. Thus, the first stop on the train of thought of the American rapid transit tradition must be New York practice.

New York has nine subway main lines. Five are north-south through Manhattan and four-track, three are east-west and two-track, and one avoids Manhattan entirely. Nearly all construction was done cut-and-cover between 1900 and 1940, forcing lines to hew to the street network. As New York has wide, straight streets, a trait shared with practically all American cities, this was not a problem, unlike in London, where carving right-of-way for the Underground was so difficult that every line from the third onward was built deep-bore.

With four tracks on most of the Manhattan trunks, there is local and express service. This allows trains to go around obstacles more easily, increasing redundancy. It’s in this context that New York’s 24/7 service makes sense: there is no absolute need for nighttime maintenance windows in which no train runs. This approach works less well on the two-track lines, and the L, the only one that’s two-track the entire way, has occasional work orders with very low train frequency because of single-tracking.

Outside the core of the city as it was understood during construction, lines run elevated. The standard New York el is an all-steel structure, which reduces construction costs – the First Subway’s subway : el cost ratio was 4:1, whereas today the average is about 2.5:1 even though tunneling uses the more expensive boring technique – at the cost of creating a boombox so noisy that it’s impossible to have a conversation under the tracks while a train is passing. Moreover, splitting the difference between two and four tracks, the standard el has three tracks, which allows peak-direction express service (on the 2/5, 6, and 7) or more space for trains to get around obstacles (on the 1, 4, and N/W).

Because the els are so noisy, the city stopped building them in the 1920s. The lines built in the 1930s were all underground, with the exception of one viaduct over an industrial shipping channel.

Moreover, from the 1930s onward, stations got bigger, with full-length mezzanines (the older stations had no or short mezzanines). Track standards increased, leading to an impressive and expensive array of flying junctions, contrasting with the flat junctions that characterize some older construction like the Chicago L or some foreign examples like much of the London Underground.

Finally, while New York has nine separate subway colors, its number of named lines is far greater. The system comprises several tens of segments called lines, and each route combines different lines, with complex branching and recombination. The infrastructure was never built for discrete lines with transfers between them, but rather for everywhere-to-everywhere one-seat rides, and service choices today reinforce this, with several outer lines reverse-branching to an East Side and a West Side Manhattan trunk.

I know of five urban rail networks with 24/7 service. One is the Copenhagen Metro, which is driverless and built with twin bores, making it easy for service to single-track at night for maintenance. The other four are American: the New York City Subway, PATH, PATCO, and the Chicago L. Moreover, the LIRR runs 24/7, which no other commuter rail system I know of does, even ones where an individual outlying station has comparable ridership to the entire LIRR.

The other systems have somewhat of a 24/7 envy. I’ve heard lay users and activists in Washington and the Bay Area complain that the Washington and BART shut down overnight; BART itself feels it has to justify itself to the users on this question. Right now, BART’s decision to temporarily add an hour to the nighttime shutdown window to speed up maintenance is controversial. People are complaining that service is being cut despite increases in funding. In Washington, the more professional activists understand why 24/7 service is unviable, but like BART feel like they have to explain themselves.

Local and express trains

New York is full of four-track mainlines, running both local and express trains. Chicago and Philadelphia have them as well on one line each. The other rapid transit networks in the US don’t, but like 24/7 service desire it. Washington has enough complaints about it that regular reader and Patreon supporter DW Rowlands had to write an article for Greater Greater Washington explaining why it would not be all that useful.

BART is the more interesting case. In any discussion of BART extensions, people bring up the fact that BART can’t skip stops – never mind that its stop spacing is extremely wide owing to its function as suburban rail. The average speed on BART is 57 km/h per the National Transit Database; the RER A, which is the express service here, averages around 50. At BART’s speed, the single longest express segment in New York not crossing water, the A/D between 125th and 59th Streets, would take 7 minutes; in fact it takes about 9. If anything, BART errs in having too few stations in Oakland and San Francisco.

On new-build systems, four tracks are understandable and desirable, provided the construction method is cut-and-cover, as it was in early-20th century America. The earliest subway lines built in New York had little cost premium over London and Paris even though the tunnels were twice as wide for twice as many tracks. However, cut-and-cover is no longer used in developed countries owing to its heavy impact on merchants and residents along the way; already during WW2, Chicago dug the tunnels for the Red and Blue Lines of the L using deep boring. A city that bores tunnels will find that four-track tunnels cost twice as much as two-track tunnels, so it might as well built two separate lines for better coverage.

New York, Boston, Philadelphia, and Chicago all built all-steel els. While cheaper, these structures are so noisy that by the 1930s they became untenable even in far-out neighborhoods, like on the Queens Boulevard Line. New lines in New York were underground; existing els were removed, quickly in New York and more slowly in Boston.

The newer systems built in the US avoided els entirely. BART planned to build one in Berkeley, but community opposition led to a change to an underground alignment; unlike subsequent examples of NIMBYism, Berkeley was willing to pay the cost difference. When tunnels are infeasible due to cost, American rail networks prefer at-grade rights-of-way, especially freeway medians. Rail rights-of-way are popular where available, such as on the realigned Orange Line in Boston, but freeway medians are common where rail alignments don’t exist.

The next generation of American urban rail systems, unable to tunnel in city center, turned to light rail in order to keep things at-grade. Across the border, in Canada, Vancouver built els to cover gaps in the right-of-way that turned into the Expo Line, and then built concrete els on the Millennium Line and outer Canada Line to reinforce the system. These brutalist structures are imposing, but I’ve had conversations under the viaducts in Richmond, just as I have in Paris under the mixed concrete and steel structures or in Sunnyside next to New York’s one concrete el.

Reverse-branching

New York did not invent reverse-branching. London has had it since the 1860s, when most South London railways ran separate trains to the City (at Cannon Street, London Bridge, or Blackfriars) or the West End (at Victoria or Charing Cross), and multiple North London railways ran trains to their traditional terminals or to the North London Railway for service to Broad Street. Paris has had it since even earlier: the railways operating out of Gare Saint-Lazare and Gare Montparnasse merged in 1851 and treated the two stations as reverse-branches allowing cities farther west to access both the Right Bank and the Left Bank. In both cities, this situation makes it harder to run coherent regional rail – in London the railways are spending considerable resources on disentangling the lines to increase frequency to South London’s many branches, and in Paris the fact that Montparnasse and Saint-Lazare serve similar destinations frustrated plans to connect the two stations with an RER tunnel.

Where New York innovated is in copying this practice on rapid transit, starting with the Dual Contracts era. In Brooklyn, existing as well as new outlying lines could be routed to any number of new crossings to Manhattan; in the Bronx and Eastern Brooklyn, a desire to give branches service to both the West Side and East Side led to reverse-branching even on the numbered lines, which were built from scratch and did not involve older suburban railroads.

Reverse-branching spread across the United States. Boston had it until it removed the Atlantic Avenue El, and even today, railfans occasionally talk about reverse-branching the Red Line along Massachusetts Avenue to Back Bay and Roxbury. Chicago occasionally has it depending on the arrangement of trains on the North Side; today, the Purple and Brown Lines share tracks at rush hour but then go in opposite directions on the Loop. The Broad Street Line in Philadelphia reverse-branches to Chinatown. The Washington Metro has reverse-branches in Virginia, limiting train frequency due to asymmetry at the merge points. BART designed itself to force a three-way wye in Oakland pointing toward San Francisco, Berkeley and Downtown Oakland, and East Oakland on which every pair of destinations has a direct train, or else East Oakland residents would have to change trains to access their own city center – and current plans for a second trans-Bay tube add further reverse-branches instead of using the extra capacity as an opportunity to fix the Oakland junction.

Outside the United States, I know of four reverse-branches on rapid transit that is not historically regional rail: the Delhi Green Line, the Namboku and Mita Lines in Tokyo, the Yurakucho and Fukutoshin Lines also in Tokyo, and the Northern line’s two trunks in London. Of those, the last one is slowly being disentangled: its southern end will be two separate lines once the Battersea extension opens, and its northern end will, severing the line in two, once upgrades to pedestrian circulation are completed at the branch point. Historically Toronto had a three-way wye on the subway, like BART, but it caused so many problems it was discontinued in favor of running two separate lines.

Regional rail

The most prominent feature of American rail networks is not what they do, but what they lack. American (and Canadian, and Chinese) regional rail networks remain unmodernized, run for the exclusive benefit of upper middle-class suburban office workers at the primary CBD. Details differ between cities, but even when management is theoretically part of the same agency as the rapid transit network, as in Boston, New York, and Philadelphia, in practice the commuter railroads are autonomous. There is no hint of fare integration or schedule integration.

This fact influences network design more than anything else, even the low quality of steel els. Service to any destination beyond the dense urban core, which is small outside a handful of relatively dense cities, requires building new rail from scratch. This favors low-cost, low-capacity light rail, often in freeway medians. Smaller cities, unable to afford enough light rail to convince entire counties to tax themselves to build transit, downgrade service one step further and build bus rapid transit, typically treated as a weird hybrid of Latin American busways and European bus lanes.

Does any of this work?

In one word, no. The American tradition of rapid transit clearly doesn’t work – just look at the weak ridership even in old cities like Boston and Philadelphia, whose mode shares compare with medium-size urban regions in the French sunbelt like the Riviera or Toulouse.

Or, more precisely, it doesn’t work in early-21st century America. In the rare occasion an American city manages to round up funding to build a new subway line, I would recommend looking abroad for models of both construction methods and network design. For example, as BART keeps working on designing the second tube, I would strongly advise against new branches on the East Bay – instead, one of the two tubes (old and new) should permanently serve East Oakland, with a new Downtown Oakland transfer station, and the other should serve Berkeley and Concord.

Moreover, the United States owes it to itself to aggressively modernize its mainline passenger rail network. It’s too important to let Amtrak, the LIRR, Metro-North, Metra, and other dinosaurs do what they’ve always done. Toronto’s modernization of GO Transit, named the Toronto RER after the Western world’s premier regional rail network, had wide support among transit planners, but the engineers at GO itself were against it, and Metrolinx had to drag them into the 21st century.

Where the American tradition does work is in contexts that the United States has long left behind. Booming third-world cities direly need rapid transit, and while American construction costs are not to be emulated, the concept of opening up major throughfares, laying four tracks, and covering the system is sound. The mix of underground construction in city center and elevated construction farther out (using concrete structure, not louder steel ones) is sound as well, and is already seeing use in China and India. This is especially useful in cities that have little to no legacy regional rail, in which category India and China do not qualify, but most of the rest of the third world does.

Globalization makes for grand shuffles like this one. Experts in the United States should go to Nigeria, Bangladesh, Pakistan, Colombia, Kenya, Tanzania, Angola, and the Philippines and advise people in these countries’ major cities about how to emulate rapid transit designs from early-20th century America. But in their home country these same experts should instead step aside and let people with experience in the traditions of Japan, South Korea, and the various distinct countries of Western and Central Europe make decisions.

# Transit-Oriented Suburbs

I did a Patreon poll last month with three options, all about development and transit: CBDs and job concentration in middle-income cities (e.g. auto-oriented Bangkok and Istanbul don’t have transit-oriented Shanghai’s CBD formation), dense auto-oriented city neighborhoods (e.g. North Tel Aviv), and transit-oriented low-density suburbia. This is the winning option.

In every (or almost every) city region, there’s a clear pattern to land use and transportation: the neighborhoods closer to the center have higher population density and lower car use than the ones farther away. Moreover, across city regions, there is such a strong negative correlation between weighted density and auto use that exceptions like Los Angeles are notable. That said, the extent of the dropoff in transit use as one moves outward into suburbia is not the same everywhere, and in particular there are suburbs with high transit use. This post will discuss which urban and transportation policies are likely to lead such suburbs to form, in lieu of the more typical auto-oriented suburbs.

What is a suburb?

Definitions of suburbia differ across regions. Here in Paris, anything outside the city’s 1860 limits is the suburbs. The stereotypical banlieue is in history, urban form, and distance from the center a regular city neighborhood that just happens to be outside the city proper for political reasons. It is hardly more appropriate to call any part of Seine-Saint-Denis a suburb than it is to call Cambridge, Massachusetts a suburb of Boston.

So if Seine-Saint-Denis is not a suburb, what is? When I think of suburbia, my prototype is postwar American white flight suburbs, but stripped of their socioeconomic context. The relevant characteristics are,

• Suburbs developed at a time when mass motorization was widespread. In the US, this means from around 1920 onward in the middle class and slightly later in the working class; in the rest of the developed world, the boundary ranges from the 1920s to the 1960s depending on how late they developed. Note that many stereotypical suburbs were founded earlier, going back even to the 19th century, but grew in the period in question. Brookline is famous for refusing annexation to Boston in 1873, but its fastest development happened between 1910 and 1930, straddling the 1920 limit – and indeed in other respects it’s borderline between a rich suburb and rich urban neighborhood as well.
• Suburbs have low population density, typical of single-family housing. Aulnay-sous-Bois, at 5,100 people per km^2, is too dense, but not by a large margin. Beverly Hills, which has mansions, has 2,300, and Levittown, New York, probably the single best-known prototype of a suburb, has 2,900. The urban typology can mix in apartments, but the headline density can’t be dominated by apartments, even missing middle.
• Suburbs are predominantly residential. They can have distinguished town centers, but as broad regions, they have to have a significant number of commuters working in the city. This rules out low-density central cities like Houston and Dallas (although their individual neighborhoods would qualify as suburbs!). It also rules out Silicon Valley as a region, which represents job sprawl more than residential sprawl.

The three criteria above make no mention of whether the area is included in the central city. Most of Staten Island qualifies as suburban despite being part of New York, but Newark fails all three criteria, and Seine-Saint-Denis and most of Hudson County fail the first two.

Where are suburbs transit-oriented?

I do not know of any place where suburban transit usage is higher than city center transit usage. In theory, this suggests that the best place to look for transit-oriented suburbia is the cities with the highest transit mode shares, such as Tokyo, Singapore, and Hong Kong (or, in Europe, Paris). But in reality, Singapore and Hong Kong don’t have areas meeting the density definition of suburb, and Tokyo has few, mostly located away from its vast commuter rail network. Paris has more true suburbs, but like Tokyo’s, they are not what drives the region’s high rail ridership. All four cities are excellent examples of high-density suburban land use – that is, places that meet my first and third definitions of suburbia but fail the second.

Instead, it’s better to look at smaller, lower-density cities. Stockholm and Zurich are both good models here. Even the central cities are not very dense, at 5,100 and 4,700 people per km^2. Moreover, both are surrounded by large expanses of low-density, mostly postwar suburbia.

Winterthur, Zurich’s largest suburb, is a mix of early 20th century and postwar urban typology, but the other major cities in the canton mostly developed after WW2. At the time, Switzerland was already a very rich country, and car ownership was affordable to the middle class. The story of the Zurich S-Bahn is not one of maintaining mode share through a habit of riding transit, but of running frequent commuter rail to suburbs that did not develop around it from the 1950s to the 70s.

In Stockholm, there is a prominent density gradient as one leaves Central Stockholm. I lived in Roslagstull, at the northern end of Central Stockholm, where the density is 30,000 people per km^2 and the built-up form is the euroblock. Most of the rest of Central Stockholm is similar in urban form and not much less dense. But once one steps outside the city’s old prewar core, density nosedives. City districts to the west and south, like Bromma and Älvsjö, go down to 3,000 people per km^2 or even a little less. A coworker who used to live in Kista described the area as American-style suburban. Beyond these city districts lie the other municipalities, which together form a sizable majority of the county’s population. Of those, a few (Solna, Sundbyberg) are somewhat above the density cutoff, but most are far below it.

In both Zurich and Stockholm, the city is much more transit-oriented than the suburbs. Stockholm’s congestion pricing was a city initiative; the suburbs banded together to oppose it, and eventually forced a compromise in which congestion pricing remained in effect but the revenue would be deeded to urban freeways rather than to public transportation.

And yet, neither city has a big transit use gradient – at least, not so big as Paris, let alone London or New York. Stockholm is expecting 170,000 daily metro trips from its expansion program, which barely touches Central Stockholm. Existing T-bana ridership on the suburban tails is pretty high as well (source, PDF-p. 13), as is ridership on commuter rail, which, too, barely touches Central Stockholm.

The structure of density

In my previous post, I complained that Los Angeles’s density has no structure, and thus public transit ridership is very low and consists predominantly of people too poor to buy a car. The situation in Stockholm and Zurich is the reverse. Density has a clear structure: within each suburb, there is a town center near the commuter rail station.

The histories of Zurich and Stockholm are profoundly different. Each arrived in its structure from a different route. In Zurich, the suburbs come from historic town centers that existed long before cars, often long before industrialization. 20th-century urban sprawl arrived in the form of making these historic villages bigger and bigger until they became proper suburbs. The geography helps rail-oriented suburbanization as well: the ridge-and-valley topography is such that urban sprawl forms ribbons served by commuter rail lines, especially in the southerly direction.

Stockholm’s topography is nothing like Zurich’s. There are water boundaries limiting suburb-to-suburb travel, but the same is true of New York, and yet Long Island, New Jersey, and Westchester are thoroughly auto-oriented. Instead, the structure of density came about because of government planning. Sweden built public housing simultaneously with the Stockholm Metro, so the housing projects were sited near the train stations.

This does not mean that the suburbs of Zurich and Stockholm are actually high-density. Far from it: the housing projects in the Stockholm suburbs are surrounded by a lot of parking and greenery, and the suburbs have extensive single-family housing tracts. However, the density is arranged to grade down from the train station, and there are small clusters of walkable apartment buildings in a small radius around each station. In Zurich the same structure came about with private construction and topography.

To the extent this structure exists elsewhere, it leads to higher low-density transit ridership too, for example in London and the Northeastern United States. Various West Coast American transit bloggers, like Jarrett Walker and Let’s Go LA, keep plugging the West Coast grid over the Northeastern hierarchy of density. But this hierarchy of suburbs that formed around commuter rail to the CBD produces transit ridership that, while awful by Continental European standards, is very good by American ones. Many of the suburbs in question, such as in Westchester, have 15-20% of their commuters choose transit to get to work.

Getting to higher numbers means reinforcing the structure of density and the transit that works in the suburbs, that is, regional rail (or a metro network that goes far out, like the T-bana, if that’s an option). Stations must be surrounded by development rather than parking, and this development should facilitate a somewhat transit-oriented lifestyle, including retail and not just housing. Jobs should be accessible from as many directions as possible, forming CBDs rather than haphazard town centers accessible only by road. Only this way can suburbia be transit-oriented.