# 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.

# The British Way of Building Rapid Transit

By a more than 2-1 vote among my Patreon backers, the third installment in my series about national traditions of building urban rail is the British one, following the American and Soviet ones. While rapid transit in Britain outside London is even smaller than in the US outside New York, the British tradition is influential globally for two reasons: first, Britain invented the railway as well as urban rapid transit, and second, Britain had a vast empire much of which still looks up to it as a cultural and scientific metropole.

Nonetheless, despite the fact that all rapid transit traditions technically descend from London’s, it is worthwhile talking about the British way. What London built inspired and continues to inspire other cities, but many, mainly in the United States, Japan, and Continental Europe, diverged early, forming distinct tradition. As I noted in the post about the Soviet bloc, Moscow was heavily influenced by British engineering, and its own tradition has evolved separately but began as a more orderly way of reproducing the London Underground’s structure in the 1930s.

In taxonomy, this is called a paraphyletic group. Monophyly means a taxon descending from a single ancestor, for example mammals; paraphyly means a taxon descending from a single ancestor excluding certain monophyletic subgroups, for example reptiles, which exclude mammals and birds, both of which descend from the same common ancestor.

The invention of rapid transit

Like most other things Britain became known for, like constitutional government and colonialism, rapid transit evolved gradually in London. Technically, the first railway in London, 1836’s London and Greenwich, meets the definition of urban rapid transit, as trains made some local stops, ran every 20 minutes, and were grade-separated, running on brick arches. However, it is at best an ancestor of what we think of as rapid transit, since it lacked the really frequent stops of the Underground or the New York els.

The first proper rapid transit line in London, the Metropolitan line, opened in 1863. It, too, lacked some features that are standard on nearly all rapid transit systems today: most importantly, it was not self-contained, but rather had some through-service with intercity rail, and was even built dual-gauge to allow through-service with the Great Western Railway, which at the time had broad gauge. Trains ran every 10 minutes, using steam locomotives; to limit the extent of smoke in the tunnels, the line was not fully underground but had a long trench between King’s Cross and Farringdon.

The Met line and the second Underground line, 1868’s District line, were both built cut-and-cover. However, whereas Met line construction went smoothly, the District line had to carve a right-of-way, as the city did not have adequate wide streets for serving the proposed route. The areas served, Kensington and Chelsea, were even then a tony neighborhood with expensive real estate, and the construction costs exploded due to land acquisition. In today’s terms the Met line cost about $32 million per kilometer and the District$90 million, a record that among the historical lines I know of remained unbroken until New York built the Independent Subway System in the 1930s.

The Met and District met to form a circle, and in general, London loved building circular lines. In addition to what would be called the Circle line until a revision last decade, there were two circles farther out, called the Middle Circle and Outer Circle. These were run by mainline railroads; there was still no legal distinction between the two urban railroads and the mainlines, and through-service and even some freight service continued on the Met well into the 20th century, which the company used as an excuse to delay its merger with the other Underground companies.

Even electric rapid transit took time to take shape. After the bad experience with the District line, there was no more cut-and-cover in Central London. The next line to open, 1890’s Northern line, required the invention of deep boring and electric traction; it was not the first rail line to use electricity, but was the first excluding streetcars. However, while the line looked like a normal self-contained rapid transit line, it was pulled by electric locomotives; electric multiple units only came a few years later, starting haphazardly in Liverpool in 1893 (each car required separate controls) and in the more conventional way on the Chicago L in 1897.

Spontaneous order and radial network design

Among the inventions that came out of London was the radial network design. Unlike the physical inventions like underground rail and electric traction, this was not a deliberate choice. It evolved through spontaneous order, owing to the privately-funded nature of British railways. A British railway had to obtain the approval of Parliament to begin construction, which approval would also permit compulsory purchase of land along the way, but funding was entirely private. An early proposal for an underground railway, an 1860s route running what would later become the Charing Cross branch of the Northern line, was approved but could not secure funding and thus was not built.

The upshot is that with private planning, only the strongest lines were built. The strongest travel demand was to the center of London, and thus the lines were all radial, serving either the City of London or the West End. There was no circumferential service. While there were many circles and loops, these were conceived as reverse-branches allowing some railroads to access multiple Central London terminals, or as ways to join two radials like the Met and District without having to go through the difficult process of turning a train underground in a world in which all trains had to be pulled by locomotives.

The same preponderance of radial lines can be seen in other privately-planned contexts. Today, the best-known example is the matatu network of Nairobi. It is informal transit, but has been painstakingly mapped by urbanists, and the network is entirely radial, with all lines serving city center, where the jobs requiring commuting are.

Despite the private planning, London has only a handful of missed connections between lines: it has eight, but only one, between the Met line and the Charing Cross branch of the Northern line, is a true miss between two lines – the other seven are between parallel outer branches or between two lines that intersect a few times in close succession but only have one transfer (namely, the Bakerloo and Met). This is not because private planners build connections spontaneously – Parliament occasionally demanded some minor route changes, including interchange stations at intersections.

The role of regional rail

Like rapid transit, regional rail evolved in London in a haphazard fashion. The London and Greenwich was a mainline railway and the Met line had some mainline through-service, and even the deep-level tube lines are compatible enough with mainline rail that there is some track-sharing, namely between the Bakerloo line and the Watford DC line. The trench between King’s Cross and Farringon was widened to four tracks and turned into a north-south through-route in the 1870s but then abandoned in the 1920s and only reactivated in the 1980s as Thameslink.

The upshot is that London ended with the bones of a regional rail network but no actual service. The ideal was self-contained Underground lines, so even when connections suggested themselves they were not pursued. For example, the original proposal for an underground line between Euston and Charing Cross involved some through-service to the railways at both ends, but when the line was finally built as the Charing Cross branch of the Northern line it was not connected to the mainline and only took over minor branches in suburban North London.

While British planners did eventually plan for through-service – plans for Crossrail date to World War Two or just afterward – by then London was not innovating but rather imitating. By the war, Berlin had already had two S-Bahn through-lines, Munich was planning one, and Tokyo had three. The modern design for Crossrail is best compared with the RER A, in a city London has treated as its primary competitor for a long time now.

Exporting London’s network design

Moscow was heavily influenced by London early on. Later on, Singapore and Hong Kong both drew on British engineering expertise. London’s status as the first city to build rapid transit may have influenced Moscow, but by the 1920s New York had surpassed it in city size as well as urban rail ridership. Moscow’s drawing on London was as I understand it accidental – the chief engineer happened to have London connections – but in Singapore, Hong Kong, Australia, and so on the relationship is colonial, with extensive cultural cringe.

In all of these non-British cities, the British design as exported was cleaner. What I mean is, the systems have a radial structure like London, but the radii are cleaner in that two lines will generally cross just once, especially in Moscow; it’s not like London, where the Central line is always north of the District line, meeting once in a tangent at Bank and Monument, or where the Victoria line and Northern line cross twice.

Another cleaner aspect is the transfer experience. Singapore and Hong Kong both make extensive use of cross-platform transfers between otherwise perpendicular lines; London only does sporadically, on the Victoria line.

A third aspect is uniformly wide interstations. London’s average interstation is about 1.25 km, which is what I think of as the standard because it is very close to the average in Tokyo and Mexico City as well, and at the time I started tracking this statistic in the late 2000s, the Chinese systems were still small. Moscow’s average is 1.7 km, and Singapore’s is similar. Hong Kong is actually divergent there: the MTR mixes core urban lines averaging about the same as in London with the more widely-spaced historically mainline East and West Rail lines and the airport express.

The relative paucity of circumferential rail is hard to judge in the export cases. Moscow came up with the idea for the Circle Line natively; there is an urban legend that it was accidentally invented by Stalin when he left a coffee cup on the map and it stained it in the shape of a circle. Hong Kong doesn’t have much circumferential rail, but its geography is uniquely bad for such service, even more so than New York’s. Singapore does have a Circle Line, but it’s one of the two worst-designed parts of the MRT, with a reverse-branch (the other one is the self-intersecting, connection-missing Downtown Line).

At the same time, it’s worth viewing which aspects British-influenced systems are getting rid of when designing cleaner version of the Underground. The most important is regional rail. Singapore has none: it has a legacy narrow-gauge rail line to Malaysia, but has never made an effort to take control of it and develop it as an urban regional rail line.

Another negative aspect exported by London is the preponderance of deep boring. I made the same complaint when discussing the Soviet bloc: while London is poor in wide arterials that a cut-and-cover subway could go underneath, Moscow is rich in them, and the same is true of Singapore.

Does this work?

London invented rapid transit as we know it, but it did so gradually and with many seams. In some sense, asking if this works is like asking if rapid transit as a technology works, for which the answer is that it is a resounding success. But when it comes to the details, it’s often the case that London has accidental successes as well as accidental mistakes.

In particular, the fact that London almost invented regional rail is a source of endless frustration and extensive retro-crayon. The Met line is almost a 19th-century Crossrail, the Widened Lines are almost a 19th-century Thameslink, and so on. Instead, as time went on the trend has been toward more self-contained lines, which is good for reliability but not when there are self-contained slow tracks of mainlines to hook into, as is planned for Crossrail and as has sporadically been the case for the Watford DC line.

The British focus on radial systems has generally been good. To the extent London has underused metro lines, it’s not because they are poorly-routed as some of the lines in Paris are, but because they serve areas that have many urban rail lines and not a lot of population density; London is not a dense city, going back to the Victorian era, when it standardized on the rowhouse as the respectable urban housing form rather than the mid-rise apartment of Continental Europe or New York.

To the credit of British-influenced planning, Singapore has managed to fit a circumferential line into its system with good connections, just with an awkward reverse-branch. London’s own circumferential transit, that is the Overground, misses a large number of Underground connections due to its separate origin in freight bypasses and mainline rail reverse-branches, where Parliament saw no point in requiring interchange stations the way it did on the Tube. However, the cleaner version seen in Singapore only misses connections involving the Downtown Line, not the Circle Line.

# 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.

# Urban Transit Vs. Commuter Transit

The Geary corridor in San Francisco is a neat model for transit ridership. The Golden Gate Park separates the Richmond District from the Sunset District, so the four east-west buses serving the Richmond – the 38 on Geary itself and the closely parallel 1 California, 31 Balboa, and 5 Fulton – are easy to analyze, without confounding factors coming from polycentric traffic. Altogether, the four routes in all their variations have 114,000 riders per weekday. The 38 and 1 both run frequently – the 1 runs every 5-6 minutes in the weekday off-peak, and the 38 runs every 5 minutes on the rapid and every 8 on the inner local.

I was curious about the connection between development and travel demand, so I went to OnTheMap to check commute volumes. I drew a greater SF CBD outline east of Van Ness and north of the freeway onramp and creek; it has 420,000 jobs (in contrast, a smaller definition of the CBD has only 220,000). Then I looked at how many people commute to that area from due west, defined as the box bounded by Van Ness, Pacific, the parks, and Fell. The answer is 28,000. Another 3,000 commute in the opposite direction.

Put another way: the urban transit system of San Francisco carries about twice as many passengers on the lines connecting the Richmond and Japantown with city center as actually make that commute: 114,000/2*(28,000 + 3,000) is 1.84. This represents an implausible 184% mode share, in a part of the city where a good number of people own and drive cars, and where some in the innermost areas could walk to work. What’s happening is that when the transit system is usable, people take it for more than just their commute trips.

The obvious contrast is with peak-only commuter rail. In trying to estimate the potential ridership of future Boston regional rail, I’ve heavily relied on commute volumes. They’re easier to estimate than overall trip volumes, and I couldn’t fully get out of the mindset of using commuter rail to serve commuters, just in a wider variety of times of day and to a wider variety of destinations.

In Boston, I drew a greater CBD that goes as far south as Ruggles and as far west as Kendall; it has a total of 370,000 jobs. Of those, about 190,000 come from areas served by commuter rail and not the subway or bus trunks, including the southernmost city neighborhoods like Mattapan and Hyde Park, the commuter rail-adjacent parts of Newton, and outer suburbs far from the urban transit system. But MBTA commuter rail ridership is only about 120,000 per weekday. This corresponds to a mode share of 32%.

I tried to calculate mode shares for the MBTA seven years ago, but that post only looked at the town level and excluded commuter rail-served city neighborhoods and the commuter rail-adjacent parts of Newton, which contribute a significant fraction of the total commute volume. Moreover, the post included suburban transit serving the same zones, such as ferries and some express buses; combined, the mode share of these as well as commuter rail ranged from 36% to 50% depending on which suburban wedge we are talking about (36% is the Lowell Line’s shed, 50% is the Providence Line’s shed). Overall, I believe 32% is consistent with that post.

Part of the difference between 32% and 184% is about the tightness of economic integration within a city versus a wider region. The VA Hospital in San Francisco is located in the Outer Richmond; people traveling there for their health care needs use the bus for this non-commuter trip. On a regional level, this never happens – people drive to suburban hospitals or maybe take a suburban bus if they are really poor.

That said, hospital trips alone cannot make such a large difference. There are errand trips that could occur on a wider scale if suburban transit were better. Cities are full of specialty stores that people may travel to over long distances.

For example, take gaming. In Vancouver I happened to live within walking distance of the area gaming store, but during game nights people would come over from Richmond; moreover, the gaming bar was in East Vancouver, and I’d go there for some social events. In Providence I’d go to Pawtucket to the regional gaming store. In the Bay Area, the store I know about is in Berkeley, right on top of the Downtown Berkeley BART station, and I imagine some people take BART there from the rest of the region.

None of this can happen if the region is set up in a way that transit is only useful for commute trips. If the trains only come every hour off-peak, they’re unlikely to get this ridership except in extreme cases. If the station placement is designed around car travel, as is the case for all American commuter lines and some suburban rapid transit (including the tails of BART), then people will just drive all the way unless there’s peak congestion. Only very good urban transit can get this non-work ridership.

# 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.