Suburban Transit-Oriented Development

Here’s a Google Maps image of Southport, a section of Fairfield, Connecticut with its own Metro-North commuter rail station:

Here’s an image at the same scale of Bourg-la-Reine, an inner suburb of Paris on the RER B, at the junction between the line’s two southern branches:

At Bourg-la-Reine, the buildings just east of the station are high-rise. There are local community amenities, including walkable schools, supermarkets, and pharmacies, and people can comfortably live in this suburb without a car. This generates significant RER traffic at all hours of day: outbound trains are often standing-room only until they reach this station even in midday, outside rush hour.

At Southport, there are a few townhouses near the station. But the roads are wide and hostile to pedestrians, and the nearest supermarket closes at 6 pm, too late for commuters returning from the city. Car ownership approaches 100%, and nobody rides the trains except to get to office jobs at the traditional peak hour in Manhattan (or perhaps Stamford).

The difference between the two places is so stark that they can barely be compared. Southport has 317 inbound boardings per weekday. Of those, 263, or 83%, are in the morning rush hour; the Metro-North-wide average is 63%, and the average on the SNCF-operated parts of the RER and Transilien is about 46%. Bourg-la-Reine has 4.5 million annual riders, about 16,000 on an ordinary working day.

A huge part of the difference is about service provision – Bourg-la-Reine has a train every five minutes midday, Southport a train every hour. But it’s not just about service. The RER has stations farther out, with somewhat less intense service, such as a train every 15 minutes, with comparable ridership. And the LIRR and Metro-North have little off-peak ridership even at stations with more frequent service, such as Mineola and Hicksville. Transit-oriented development (TOD) is as important as good service in such cases.

I bring up Southport because the RPA just dropped a study about suburban TOD that grades every New York commuter rail station between 0 and 3, and gives Southport the highest mark, 3. The RPA study looks at zoning within 800 meters of each station and considers whether there’s a parcel of land that permits multifamily housing with a floor are ratio higher than 1.25. Southport has such lots, supporting some townhouses, so according to the RPA it gets full marks, even though, by RER standards, it is like every other American car-oriented suburb.

Based on this methodology, the RPA identifies a number of good suburbs, and even comes to policy conclusions. It proposes more TOD in the mold of existing exurban New York examples, such as Patchogue. The model for the program is the real reason the RPA study is so weak: rather than calling into attention the big differences between land use at suburban stations in New York versus in Paris (or any number of big European cities with suburban rapid transit), it overfocuses on small differences within auto-oriented suburbia.

Some of the ultimate conclusions are not terrible. For example, the RPA is proposing linking federal infrastructure development to permitting more multifamily housing. This would improve things. However, the problem with this is twofold. First, it is unrealistic – the federal government gave up decades ago on enforcing fair housing laws, and has no interest in attempting to make exclusionary suburbs behave. Were I to propose this, hordes of American commenters would yell at me for not understanding American politics. And second, it misunderstands the nature of the problem, and ends up proposing something that, while unrealistic, is still low-impact.

The best way to understand the problem with the study is what author Moses Gates told me on Twitter when I started attacking it. He said that the RPA was looking at zoning rather than actual development. Since there is zoning permitting multifamily development within the prescribed radius at Southport, it gets full marks. With my understanding of what good TOD looks like, I would be able to say that this is clearly so bad the methodology must be changed; on Twitter I suggested looking at zoning within 300 meters of the station rather than 800, since the highest-intensity development should be right next to the station. I also suggested looking at supportive nonresidential uses, especially supermarkets. A development that isn’t walkable to retail at reasonable hours is not TOD.

The RPA does not think in this language. It thinks in terms of internal differences within the US. Occasionally it deigns to learn from London, but London’s suburban development is auto-oriented by European standards (transit mode share in the London commuter belt is at best in the teens, often in the single digits). Learning from anywhere else in the world, especially places that don’t speak English, is too difficult. This means that the RPA could not reach the correct conclusion, namely, that there is no such thing as an American suburb with TOD. The only exception I can come up with in the United States involves Arlington, on the Washington Metro, and Arlington is no longer considered a suburb, but really a full-fledged city in a different state, like Jersey City.

The other thing the RPA missed is that it drew too large a radius. TOD at a train station should include townhouses 800 meters out – but it’s more important to include high-rise residential construction next to the train station and mid-rise apartment buildings 500 meters out. Giving American suburbs latitude to place TOD so far from the station means they will act like Southport and allow small amounts of multifamily housing out of the way, while surrounding the station itself with parking, a tennis court, and large single-family houses with private swimming pools. This is not hypothetical: suburbs in New Jersey have reacted to court rulings mandating affordable housing by permitting apartments at the edge of town, far from supporting retail and jobs, and keeping the town core single-family.

Because the RPA missed the vast differences in outcomes between the US and France, it missed some useful lessons:

  • States should centralize land use decisionmaking rather than give every small suburb full autonomy.
  • TOD doesn’t need to be fully mixed-use, but there should be some local retail right next to housing.
  • Housing should be high-density right next to the station. A floor area ratio of 1.25 is not enough.
  • Publicly-funded social housing should be next to train stations, in the city as well as in the suburbs, and this is especially important in expensive suburbs, which aren’t building enough affordable housing.

Without suburban TOD, any regional rail system is incomplete. I wish I could have covered it at my talk, but I didn’t have time. Good service needs to run to dense suburbs, or at least suburbs with dense development within walking distance of the station. It needs to extend the transit city deep into suburbia, rather than using peak-only commuter rail to extend the auto-oriented suburbs into the city.

I Gave a Talk About Regional Rail

I expect there will be writeups about the talk (e.g. on Streetsblog). But meanwhile, here are my slides (warning: 17 MB, because of pictures). These are identical to what was shown at the talk, with two differences: I fixed one small mistake (Fordham Road vs. Pelham Parkway), and I consolidated the pauses, so each slide is a page, rather than a few pages, each page adding a line.

There were light fantasy maps in the talk. Because of size, I’m not embedding them in the post. But there are links:

Yellow highlights around a line indicate it’s new; Gateway is highlighted in one direction since it’s an existing two-track line to be four-tracked. On the infill map, solid circles are existing stations, gray circles are planned stations, white circles are my suggestions for additional infill.

There’s More Redundancy Than You Think

I was visiting Boston last week, and am in New York this week; you can see me at NYU on Thursday tomorrow. Last week, I met with TransitMatters activists talking about bus and rail improvements in Boston, and on the way saw something that made me understand two things. First, the MBTA is run by incompetent people. And second, even two subway lines that are perpendicular and serve completely different areas can be redundant with each other.

Two and a half years ago, I said redundancy is overrated. In this post, I’d like to argue from the opposite direction: transit networks have more redundancy than they appear to. One implication is identical to that of my older post: transit agencies should build subway lines without regard for redundant service, since not only is redundancy overrated, but also a new subway line is redundant with old lines even if they serve completely different areas. But the other implication concerns service interruptions and shutdowns.

The issue in Boston is that, although there are nighttime shutdowns, there are also occasional weekend shutdowns, as in New York, for major capital projects. The Red Line is being closed on weekends for two months on the segment between Boston proper and Cambridge. But the Orange Line is also being closed on weekends on segments, after deferred maintenance led to a meltdown in the last two months, with frequent delays and slow zones. Last weekend, I found myself having to go between Davis Square (on the Red Line, just off the edge of the map) and Jamaica Plain (near the bottom of the Orange Line) to visit Sandy Johnston, with the highlit segments shut down:

Shuttle buses replaced the subway on both segments. On the Red Line, the MBTA contracted it out to a private company that used wheelchair-inaccessible high-floor buses; there were not enough MBTA bus drivers to run the shuttles on both segments, and by union rules the MBTA could not use contract drivers on its own buses even though it did have the equipment, forcing it to use inferior private-sector buses. I am able-bodied enough to climb high-floor buses, but I would not use the shuttle buses replacing the Red Line for another reason: as can be seen in the map, there is no continuous street grid between Charles/MGH and Park Street. If there were a crossover right east of Charles/MGH then only the Kendall-MGH segment would be bustituted, and there, the buses would go on Longfellow Bridge, with a serious but not fatal slowdown. But between Kendall and Park Street the buses have to swerve through side streets that were not designed for fast traffic; in 2012, I was on such a shuttle and as I recall the trip took 15 or 20 minutes, where the subway does it in about 5.

Instead of relying on shuttles, I took a bus north of the river to get to Lechmere and use the Green Line to reach Chinatown on a chain trip. From Chinatown the options were all bad, and I rode the 39 bus, which parallels the Green Line E Branch (the southernmost one) and continues south to Forest Hills, where the Green Line once ran as well. The way back was not a chain trip, and with a bus-bus-Red Line trip and no 39 bus in sight (the online bus tracker was down), I gave up and took a taxi.

The Red Line and Orange Line look like they go in different directions, so shutting down one does not affect the other. But in reality, in a city with buses, taking the bus to a different line is a common strategy to deal with shutdowns – hence, using the Green Line to get between Davis and Chinatown, taking a bus in a place where the buses are less slow than between Charles/MGH and Park Street.

If any city in North America did not use buses at all, it would be Boston. It has legendarily narrow and twisted streets, and crawling buses. It has higher rail-to-bus ridership ratio than any other American city except possibly New York, and far higher ratio than the major English Canadian cities with their bus grids. Its transit network, inherited from midcentury, uses the buses to feed the subway, and has no bus service through downtown, where even before mass motorization there were traffic jams of streetcars.

But even in Boston, using the bus outside the core to get to a better subway line is possible, and normal when there are service interruptions. This means that any pair of subway lines could potentially be redundant with each other. This means that it is bad practice to shut down more than one line at once for repairs. The reason the Orange Line needs emergency repairs in the first place is that the MBTA maintained it poorly and wouldn’t act when it was less urgent, such as six months ago (Sandy reports noticing a consistent deterioration in service since January). Today, the shutdowns are probably unavoidable. But the Red Line shutdowns, for a capital construction project involving the Longfellow Bridge, can be delayed. The MBTA should do that in the future in order to both avoid having to use inaccessible buses and allow passengers to take a circumferential bus to a functioning subway line.

Fix DeKalb Avenue

In New York, there are two dedicated subway tracks on the Manhattan Bridge offering a bypass of Lower Manhattan. Between DeKalb Avenue in Brooklyn and Canal Street in Chinatown in Manhattan, Q trains run nonstop for 3.5 km, while the R train goes the long way, taking 5.5 km and making 2 intermediate stops in Downtown Brooklyn and 4 in Lower Manhattan. The N skips DeKalb Avenue, with a 4.5 km nonstop segment between Canal Street and the Atlantic/Pacific/Barclays station complex.

The Q and N should be immense time savers. Instead, the Q does the trip in 8 minutes and the N in 10, both of which average 26-27 km/h. The subway’s overall average speed, weighed down by local trains stopping every 700 meters, is 29 km/h. The Q and N are still time savers, though, because the R does the 5.5 km in 18 minutes, an average speed of 16 km/h – far less than the systemwide average, and even less than the slowest Paris Metro line, Line 4 with its 500-meter interstations and 20 km/h average speed. Between DeKalb and Pacific, about 800 meters, the R takes 3 minutes. Unfortunately, New York City Transit is not taking any measures that would fix this, and when I asked about one possibility, I got excuses.

There are two reasons why this part of the subway is so slow. The first is something called signal timers. Timers are devices installed at frequent intervals on long interstations, such as the bridges and tunnels connecting Manhattan with Brooklyn and Queens, limiting train speed. These timers have always been around, but after fatal accidents in the 1990s, New York City Transit tightened them, reducing speed further; for some more background, see my Vox piece from last summer. The timers are more safety theater than safety. The biggest conclusion I reached from looking at the accident postmortem on the NTSB and some NYCT information was “make sure your trains’ brakes work as intended”; NYCT derated the trains’ service and emergency braking rates later in the 90s, which marginally reduces maintenance costs but is bad for safety and brutal for train speed.

The second reason is the switches at DeKalb Avenue. DeKalb is a six-track station, with four tracks feeding the Manhattan Bridge and two feeding the tunnel through Lower Manhattan. The two tunnel tracks then continue to the south as local tracks on the Fourth Avenue Line, carrying the R; this is the least used of all subway trunk lines into Manhattan, because the detour and low speed make it useless for most Midtown-bound passengers. The four bridge tracks include two express tracks at DeKalb going to the Brighton Line, and two super-express tracks skipping DeKalb continuing to the south as express Fourth Avenue tracks. Today, there is a splitting and recombining of branches. The B and D run together from Sixth Avenue to the Manhattan Bridge, and the N and Q run together from Broadway, but just north of DeKalb they recombine as B and Q running to Brighton, and D and N running super-express down Fourth Avenue.

This recombination at DeKalb slows down trains considerably, in two ways. First, the interlocking is complex. You can see it on this map on NYCSubway.org; in addition to splitting and recombining the B, D, N, and Q, it also has a non-revenue connection allowing R trains to serve the Brighton Line. Trains on diverging turnouts go at glacial speeds. And second, trains from four lines influence one another’s schedules, and delays propagate. Supervising train movements is thus difficult, and control center has to have a camera watching the trains enter the interlocking to ensure they adhere to schedule; timetables have to take the resulting delays into account.

When I first complained about reverse-branching in New York, I talked about capacity limits imposed by having more trunk lines than branches, a situation that is still to some extent true going north and east of Midtown. At DeKalb, there are six tracks going in and six going out, but the recombination makes things slower, and should be removed. NYCT should make a decision between having B and D trains run on the Brighton Line and the N and Q on Fourth Avenue, or the reverse. The interlocking permits either option, with entirely grade-separated junctions, allowing the trains on the two lines to no longer interfere with each other’s operations.

I in fact asked NYCT about it by proxy. NYCT dismissed the idea, on the grounds that transfer volumes between the B/D and N/Q would be too big. At Atlantic/Pacific, the Pacific side has a cross-platform transfer between the local R and express D/N, but going between the Pacific side and the Atlantic side (the B/Q, and separately the 2/3/4/5) involves a lot of walking. NYCT believes that passengers would flood the corridors looking for a train to their preferred destination, and the transfer volumes would require trains to have long dwell times. NYCT said nothing about whether the overall speed would actually fall, but I believe that based on the large transfer volumes NYCT predicts, passenger trip times (including transfer times) would rise. The only problem: I don’t believe NYCT’s prediction is true at all.

The B and D trains go express up Sixth Avenue, making stops at Grand Street in Chinatown, Broadway-Lafayette on Houston Street, West Fourth Street in the Village, and Herald Square. The N and Q trains go express up Broadway, serving Canal Street in Chinatown, Union Square, and Herald Square. North of Herald Square the two lines are never more than one long block apart until they leave Midtown. Passengers going toward Midtown are unlikely to have strong opinions about which of the two lines they would prefer.

Passengers going to destinations between Manhattan Bridge and Midtown might register stronger preferences. Union Square is the fourth busiest subway station in New York, and is quite far from the B and D. The closest alternative using the B and D is to change cross-platform to the M or F at West Fourth, and get off at 14th Street and Sixth Avenue, two long blocks from Union Square. Three more stations are potential concerns: Canal Street ranks 18th, West Fourth ranks 21st, and Broadway-Lafayette ranks 25th. Getting to Broadway-Lafayette from the N or Q is easy: the station and Canal Street are both on the 6, and passengers can transfer to the 6 at Canal.

West Fourth and Canal remain concerns, but they are not huge ones; they are secondary destinations. Canal is only a major destination for Chinese-New Yorkers, and in Brooklyn they cluster in Sunset Park along Fourth Avenue, suggesting that the Fourth Avenue express tracks should carry the N and Q and the Brighton tracks should carry the B and D. The urban geography of Chinese-New Yorkers is changing due to the combination of fast immigration and fast integration and migration to the suburbs, but this is a service decision, not an infrastructure investment; it can be reversed if demographics change.

Moreover, as a destination, West Fourth is predominantly used for NYU. The Village is a dense residential neighborhood, and West Fourth allows its residents to easily reach Lower Manhattan, Downtown Brooklyn, and two different four-track trunk lines through Midtown. But it has few jobs, outside NYU, which lies mostly between Sixth Avenue and Broadway. Union Square can adequately serve people going toward NYU, and stations on the R and 6 to the south can serve people going to NYU even better. The one problem is that the transfer between the R and the N/Q at Canal Street is not cross-platform; the cross-platform transfers start at Union Square. But with coverage of multiple stations walkable to NYU, the loss of the one-seat ride to West Fourth is not fatal. Even the transfer to the A, C, and E trains at West Fourth has alternative options: passengers from the N or Q going to the E can transfer to the F or M at Herald Square and reach the same stations, and passengers going to the A or C can transfer to the 1 at Times Square and to the A or C at Columbus Circle, both of which transfers are not much harder than climbing two flights of stairs at West Fourth.

With so many options, not many riders would be connecting at Atlantic/Pacific, and trains could keep dwell times short. If anything, dwell times might be shorter, because missing a train would be less fatal: the next train on the same track would serve the same destinations in Midtown, so riders would only need to wait about 3 minutes at rush hour, and 5 minutes off-peak. The gain in speed would be substantial, with the interlocking imposing fewer operational constraints.

NYCT might need to slightly rework the switches, to make sure the chosen matching of the lines in Manhattan and Brooklyn takes the straight and not the diverging direction at the turnouts; typically, the straight direction imposes no speed limit (up to full line speed on high-speed rail lines), but the diverging direction is slow. A matching in which the B and D go on Brighton and the N and Q on Fourth Avenue express to my understanding already involves only one diverging move, if I am reading the track map linked on NYCSubway.org correctly. At the same time, NYCT could fix the switches leading to the R: there was through-service from the Brighton Line to the tunnel tracks the R uses today, but there no longer is, so this out-of-service connection should get diverging and not straight moves. But even with the R, the capital investment involved is minimal.

I do not know the potential travel time gains between DeKalb and Canal Street (or Grand Street) with no timers or reverse-branching. With straight tracks across Manhattan Bridge, and wide curves toward Grand Street, 3.5-minute trips are aspirational, 4-minute trips are still possible, and 5-minute trips should be easy. From Pacific Street, add one more minute, corresponding to cruising at 50 km/h, a speed limit the subway routinely attains even on local tracks. This saves passengers from DeKalb about 4 minutes, and passengers from Pacific about 5. The average trip across the system is about 21 minutes, and the average delay (“excess journey time“) is 3 minutes. The saving would be immense, and contribute to both more casual ridership between Brooklyn and Manhattan, and lower operating costs coming from faster trips.

NYCT should not make excuses for this. The timers may have been originally justified as a safety improvement, but reducing train braking rates had the opposite effect. And, uniquely among the various reverse-branch points in New York, DeKalb feeds two Manhattan trunks that are very close to each other, especially in Midtown, to the point that one-seat rides to every stop have limited value. It should make a decision about whether to run the B/D together on Fourth Avenue and the N/Q on Brighton (switching the Q and D) or the reverse (switching the B and N), based on origin-and-destination data. Some passengers might bemoan the loss of one-seat rides, but most would cheer seeing their trips sped up by 4-5 minutes.

Little Things That Matter: Vertical Circulation

Chatelet-Les Halles has a problem with passenger circulation. It has exceedingly wide platforms – the main platforms, used by the RER A and B, are 17 meters wide – but getting between the platform level and the rest of the station runs into a bottleneck. There are not enough stairs and escalators between the platform and the mezzanine, and as a result, queues develop after every train arrival at rush hour. Similar queues are observed at the Gare du Nord RER platforms. The situation at Les Halles is especially frustrating, since it’s not a constrained station. The platforms are so wide they could very easily have four or even six escalators per access point flanking a wide staircase; instead, there are only two escalators, an acceptable situation at most stations but not at a station as important as Les Halles.

This is generally an underrated concern in the largest cities. In smaller cities, the minimum number of access points required for coverage (e.g. one per short subway platform, two per long platform) is enough even at rush hour. But once daily ridership at a station goes into the high five figures or the six figures, a crunch is unavoidable.

There are two degrees of crunch. The first, and worse, is when the capacity of the escalators and stairs is not enough to clear all passengers until the next train arrives. In practice, this forces trains to come less often, or to spread across more platforms than otherwise necessary; Penn Station’s New Jersey Transit platforms are that bad. The situation at Les Halles and Gare du Nord is a second, less bad degree of crunch: passengers clear the platform well before the next train arrives, but there’s nonetheless a significant queue at the bottom of the escalator pits. This adds 30-60 seconds to passenger trip times, a nontrivial proportion of total trip time (it’s a few percent for passengers within the city and inner suburbs). Avoiding even the less bad crunch thus has noticeable benefits to passengers.

The capacity of a horizontal walkway is 81 passengers per minute per meter of width (link, p. 7-10). This is for bidirectional travel. Unidirectional capacity is a little higher, multidirectional capacity a little lower. Subway platforms and passages are typically around 5 meters wide, so they can move 400 passengers per minute – maybe a little more since the big crunch is passengers heading out, so it’s unidirectional with a few salmons (passengers arrive at the station uniformly but leave in clumps when the train arrives). Busier stations often have exits at opposite ends of the platform, so it’s really 400*2 = 800. Queues are unlikely to form, since trains at best arrive 2 minutes apart, and it’s uncommon for a train to both be full and unload all passengers at one station.

An escalator step can be 60 cm, 80 cm, or 1 meter wide, with another 60 cm of handrail and gear space on both sides. On public transit, only the widest option is used, giving 1.6 meters of width. The theoretical capacity is 9,000 passengers per hour, but the practical capacity is 6,000-7,000 (link, p. 13), or 100-120 per minute. This is more than pedestrian walking capacity per unit of step width, but less per unit of escalator pit width. So a pedestrian walkway ending in a battery of escalators will have a queue, unless the width of the escalator bank is more than that of the walkway leading to it.

Moreover, escalators aren’t just at the end of the station. The busiest train stations have multiple access points per platform, to spread the alighting passengers across different sections of the platform. But mid-platform access points have inherently lower capacity, since they compete for scarce platform width with horizontal circulation. It appears that leaving around 2 meters on each side, and dedicating the rest to vertical circulation, is enough to guarantee convenient passenger access to the entire platform; in a crunch, most passengers take the first access point up, especially if there’s a mezzanine (which there is at Les Halles).

Should New York invest in better commuter rail operations, it will face a bigger risk of queues than Paris has. This is for two reasons. First, New York has much higher job density in Midtown than Paris has anywhere, about 200,000/km^2 vs. perhaps 100,000 around La Defense and the Opera (my figures for both areas in Paris have huge fudge factors; my figure for New York comes from OnTheMap and is exact). And second, Manhattan’s north-south orientation makes it difficult to spread demand across multiple CBD stations on many commuter rail lines. One of the underrated features of a Penn Station-Grand Central connection is that through-trains would have passengers spread across two CBD stops, but other through-running regional rail lines would not have even that – at best they’d serve multiple CBDs, with one Midtown stop (e.g. my line 4 here).

When I computed the needs for vertical circulation at a Fulton Street regional rail station in this post, I was just trying to avoid the worse kind of crunch, coming up with a way to include 16 platform-end escalators (12 up, 4 down in the morning peak) and 16 mid-platform escalators (8 up, 8 down) on a 300-meter long two-level station. It’s likely that the escalator requirement should be higher, to avoid delaying passengers by 1-1.5 minutes at a time. With four tracks (two on a Grand Central-Staten Island line, two on a Pavonia-Brooklyn line) and 12-car trains arriving every 2 minutes, in theory the station could see 240,000 incoming passengers per hour, or 4,000 per minute. In reality, splitting passengers between Grand Central and the Financial District on what I call line 4 means that a sizable majority of riders wouldn’t be getting off in Lower Manhattan. When I tried to compute capacity needs I used a limit passenger volume of 120,000 per hour, and given Midtown’s prominence over Lower Manhattan, even 90,000 is defensible.

90,000 per hour is still 1,500 per minute, or 3,000-4,000 if we are to avoid minute-long queues. A single up escalator is limited to about 100-120 people per minute, which means that twenty up escalators is too little; thirty or even forty are needed. This requires a wider platform, not for horizontal passenger circulation or for safety, but purely for escalator space, the limiting factor. I proposed an 8-meter platform, with space for four escalators per end (two ends per platform, two platforms on two different levels), but this suggests the tube diameter should be bigger, to allow 10-meter platforms and six escalators per end, giving four up escalators per end. This is 16 up escalators. Another 16-20 up escalators can be provided mid-platform: the plan for eight up escalators involved eight access points interspersed along the platform, and 10-meter platforms are wide enough width to include three escalators (two up, one down) per bank and on the border of allowing four (three up, one down).

The situation at the Midtown stations in New York is less constrained. Expected volumes are higher, but Grand Central and Penn Station both spread passengers among multiple platforms. In the near term, Penn Station needs to add more vertical circulation at the New Jersey Transit platforms. The LIRR remodeled its section of the station to add more access points in the 1990s (e.g. West End Concourse), but New Jersey Transit is only doing so now, as part of phase 1 of Moynihan Station, and it’s still not adding as many, since its platforms are shorter and don’t extend as far to the west.

Nonetheless, given the number of proposals out there for improving Penn Station, including ReThinkNYC and Penn Design’s plan, it’s important to think of longer-term plans for better vertical circulation. When I proposed eliminating Penn Station’s above-ground infrastructure, I came up with a design for six approach tracks (including a new Hudson tunnel connecting to Grand Central), each splitting into two platform tracks facing the same platform; the six platforms would each be 15 meters wide, but unlike Les Halles, each of six access points would have six escalators, four up and two down in the morning peak, or alternatively four escalators and a wide staircase (the climb is 13 meters, equivalent to a five-floor walkup). There would be ample capacity for anything; emptying a full 12-car train would take forty seconds, and it’s unlikely an entire 12-car train would empty.

Neighborhoods With Excess Capacity

In New York, the tech industry has clustered in the Meatpacking District, around 14th Street and 8th Avenue. Google’s building (the company’s largest office outside the Googleplex) is there, Samsung’s New York offices are there, startup incubators are there with co-working spaces. Stephen Smith has called for commercial upzoning there (on YIMBY three years ago, and on Twitter just now), despite NIMBY objections. He argues not only that there is pent-up demand for office space, but also that there is excess subway capacity there: “the L train’s capacity west of Union Square is essentially unlimited, after the hordes from Brooklyn headed to destinations east of Broadway change for the 4/5/6 and N/Q/R.” While his other arguments for upzoning are solid, this one is incorrect, and I’d like to explain which areas have excess capacity and which don’t.

Two years ago, I wrote this post about modeling transit crowding. The model is primitive – it assumes a one-dimensional city, 100% mode share, and independent job and residence distributions. For the purposes of this post, cities A, B, and C from the model are not relevant (they have perfect mixture of jobs and residences); cities D, E, and F, with separation of residences and jobs, are more relevant, with city F, with partial mixture, the most useful.

The results of the model are fairly predictable. In the morning peak, transit vehicles (or roads!) fill up toward the center as they pass through residential areas, and then empty in the commercial core. This means that more residences outward of the point of greatest congestion, and more jobs inward of it, add more crowding; more jobs outward of the point, and more residences inward of it, do not. More jobs on the other side of city center add to crowding, because people still ride through the point of greatest crowding.

On the L, the point of greatest crowding is between Bedford Avenue (the last stop in Brooklyn) and First Avenue (the first in Manhattan). This means that more residential development on the L in Brooklyn and more commercial development in Manhattan would add crowding – even commercial development on the West Side would attract riders living in Brooklyn, who would ride through the overcrowded segment under the East River. The other subway lines serving the Meatpacking District suffer from the same problem: those are the 2 and 3 at 7th Avenue and 14th Street, and the A, C, and E at 8th Avenue. With Second Avenue Subway having taken some crowds off the 4 and 5 on the East Side, it’s likely the 2, 3, and E are the most crowded subway lines in New York today (the A has more room). Yes, most riders on those lines get off in Midtown, but it doesn’t matter, because riders from the Upper West Side and Queens, attracted to new jobs in the Meatpacking District, would still ride through the most crowded point, at the entry to Midtown.

So if not the Meatpacking District, where is it better to add jobs, purely from the perspective of subway crowding? Superficially, the answer is to mix them across the residential parts of the city. But here, my model runs into problems with mode share. The model says that adding jobs in (say) Downtown Brooklyn increases subway crowding, because of riders from Uptown Manhattan riding to the south. Per the model, it’s best to add jobs on the side with more crowding, which is the north and Queens sectors, not the Brooklyn sector, where only the L is very crowded. This means, more jobs on the Upper East and West Sides, and maybe also in Long Island City, near Queensboro Plaza.

But in reality, there is some travel segmentation in New York. People who work on the Upper East and West Sides probably live in those neighborhoods or in Harlem and the Bronx, and people who work in Downtown Brooklyn probably live elsewhere in Brooklyn. Yes, it’s possible to commute between the Upper East Side and Downtown Brooklyn, but people would not ordinarily choose to do so – the commute is long and crowded (because of all the Midtown-bound workers), and there isn’t much saving on rent. People might still do it for various reasons, like a two-body problem or moving frequently between jobs – this is why through-running is important – but it’s much less common than living and working on the same side of city center.

So most likely, office development in Downtown Brooklyn would mainly attract ridership from within Brooklyn. Extra ridership from Uptown Manhattan and the Bronx is likely to be small. The upshot is that locations outside the most crowded point on each inbound subway line are likely to lead to large gains in subway ridership without much additional crowding.

I bring up Downtown Brooklyn and not just the Upper West and East Sides because it is better-connected to more bedroom communities by subway. These include the Lower East Side and Chinatown, Long Island City, and nearly all of Brooklyn. Long Island City is also highly accessible, from much of Queens and the parts of Brooklyn on the G train. But the Upper West and East Sides aren’t so accessible because of the lack of good east-west subway options.

Of course, the situation on the ground is different. New York is desperate to add tech jobs in Downtown Brooklyn, but the tech industry insists on clustering in the Meatpacking District. There’s only so much a city can force developers to site themselves in the areas most convenient for infrastructure. But from a long-term capacity standpoint, it’s in New York’s interest to encourage commercial development outside the Manhattan core, especially in areas that get decent subway service from multiple directions, like Long Island City, Downtown Brooklyn, and maybe Jamaica.

It would be easier if there were more service targeted at off-core destinations. This is part of why I harp on regional rail all the time – the LIRR would be able to serve Downtown Brooklyn and Jamaica better if it didn’t exist just for the benefit of suburban salarymen working in Midtown. But this also includes Triboro, which would give multidirectional service to nodes including Jackson Heights, the Bronx Hub, and Brooklyn College. This would encourage developers to build commercial at these nodes, which suffer from poor access to workers today.

Note that opening circumferential transit, in this model, has the opposite of the expected effect on radial lines. Normally, a new transit line reduces demand on parallel lines and increases demand on intersecting lines, which runs the risk of overloading them. But if a circumferential line encourages office development at intersection points with radials, it will still encourage more ridership on the radials, but this ridership will completely miss the congested inner portions of the radials.

Suspended Railways

Suspended railways are not a common mode of transportation. In Europe, the best-known example is the Wuppertal Suspension Railway, opened in 1901. Two examples exist in Japan, which is more willing to experiment with nonstandard rail technology. With essentially just these three examples in normal urban rail usage, it is hard to make generalizations. But I believe that the technology is underrated, and more cities should be considering using it in lieu of more conventional elevated or underground trains.

The reason why suspended trains are better than conventional ones is simple: centrifugal force. Train cars are not perfectly rigid – they have a suspension system, which tolerates some angle between the bogies and the carbody. Under the influence of centrifugal force, the body leans a few degrees to the outside of each curve:

 

If the train is moving away from you, and is turning left, then the outside of the curve is to your right; this is where the body leans in the image on the right. This is because centrifugal force pushes everything to the right, including in particular the carbody. This increases the centrifugal force felt by the passengers – the opposite of what a tilt system does. A train is said to have soft suspension if this degree of lean is large, and rigid suspension if it is small. The depicted image is rotated 3 degrees, which turns 1 m/s^2 acceleration in the plane of the tracks into 1.5 m/s^2 felt by the passengers; this is the FRA’s current limit, and is close to the maximum value of emergency deceleration. There are no trains with perfectly rigid suspension, but the most recent Shinkansen trains have active suspension, which provides the equivalent of 1-2 degrees of tilt.

On a straddling train, this works in reverse. A straddling train moving away from you turning left will also suspend to the right:

 

It’s almost identical, except that now the floor of the train leans toward the inside of the curve, rather than to the outside. So the suspension system reduces the lateral acceleration felt by the passengers, rather than increasing it. By softening the suspension system, it’s possible to provide an arbitrarily large degree of tilt, limited only by the maximum track safety value of lateral acceleration, which is not the limiting factor in urban rail.

This is especially useful in urban rail. Longer-distance railroads can superelevate the tracks, especially high-speed tracks, where trains have to be reliable enough for other reasons that they never have to stop in the middle of a superelevated curve. Some urban rail lines have superelevation as well, but not all do. Urban rail lines with high crowding levels routinely stop the trains in the middle of the track to maintain sufficient spacing to the train ahead; this is familiar to my New York readers as “we are being delayed because of train traffic ahead of us,” but the same routinely happens in Paris on the RER. This makes high superelevation dicey: a stopped train leans to the inside of the curve, which is especially uncomfortable for passengers. High superelevation on urban rail is also limited by the twist, i.e. the rate at which the superelevation increases per linear meter (in contrast, on intercity rail, the limiting factor is jerk, expressed in superelevation per second).

Another reason why reducing curve radius is especially useful in urban rail is right-of-way constraints. It’s harder to build a curve of radius 200 meters in a dense city (permitting 60 km/h with light superelevation) than a curve of radius 3 km outside built-up areas (permitting 250 km/h with TGV superelevation and cant deficiency). Urban rail systems make compromises about right-of-way geometry, and even postwar systems have sharp curves by mainline rail standards; in 1969, the Journal of the London Underground Railway Society listed various European limits, including Stockholm at 200 meters. The oldest lines go well below that – Paris has a single 40-meter curve, and New York has several. Anything that permits urban rail to thread between buildings (if above ground), building foundations (if underground), and other lines without sacrificing speed is good; avoiding curves that impose 30 km/h speed limits is important for rapid transit in the long run.

Suspended railways are monorails, so they run elevated. This is not inherent to the technology. Monorails and other unconventional rail technologies can go underground. The reason they don’t is that a major selling point for monorails is that their sleek structures are less visually obtrusive when elevated. But underground they can still use the same technology – if anything, the difficulty of doing emergency evacuation on an elevated suspended monorail is mitigated on an underground line, where passengers can hop to the floor of the tunnel and walk.

I’d normally say something about construction costs. Unfortunately, the technology I am plugging has three lines in regular urban operation, opened in 1901, 1970, and 1988. The 1988 line, the Chiba Monorail, seems to have cost somewhat more per km than other contemporary elevated lines in Japan, but I don’t want to generalize from a single line. Underground there should not be a cost difference. And ultimately, cost may well be lower, since, at the same design speed, suspended monorails can round tighter curves than both conventional railroads and straddle monorails.

Despite its rarity, the technology holds promise in the most constrained urban environments. When they built their next new metro lines, disconnected from the older network, cities like New York, London, Paris, and Tokyo should consider using suspended railroads instead of conventional subways.

Fare Integration

I said something on my Patreon page about fare integration between buses and trains, in the context of an article I wrote for the DC Policy Center about improving bus service, and got pushback of the most annoying kind, that is, the kind that requires me to revise my assumptions and think more carefully about the subject. The controversy is over whether fare integration is the correct policy. I still think it is, but there’s a serious drawback, which the positive features have to counterbalance.

First, some background: fare integration means that all modes of public transit charge the same fare within the same zone, or between the same pair of stations. Moreover, it means transfers are free, even between modes. Fare integration between city buses and urban rail seems nearly universal; big exceptions include Washington (the original case study) and London, and to a lesser extent Chicago. Fare integration between urban rail and regional rail is ubiquitous in Europe – London doesn’t quite have it, but it’s actually closer than fare integration between buses and the Underground – but does not exist in North America. In Singapore there is fare integration. In Tokyo, there are about twelve different rail operators, with discounted-but-not-free transfers between two (Tokyo Metro and Toei) and full-fare transfers between any other pair.

The reason North American commuter rail has no fare integration with other forms of transit is pure tradition: railroaders think of themselves as special, standing apart from mere urban transit. We can dispense with the idea that it is a seriously thought-out fare system. However, lack of integration between buses and trains in general does have some thought behind it. In London, the stated reason is that the Underground is at capacity, so its fares are jacked up to avoid overcrowding, while the buses remain cheap. In Washington, it’s that Metro is a better product than the buses, so it should cost more, in the same way first-class seats cost more than second-class seats on trains. Cap’n Transit made a similar point about this in the context of express buses.

There are really three different questions about fare integration: demand, supply, and network effects. The first one, as noted by Patreon supporters, favors disintegrated fares. The other two favor fare integration, for different reasons.

Demand just means charging more for a product that has higher demand. This is about revenue maximization, assuming fixed service provision: people will pay more for the higher speed of rapid transit, so it’s better to charge each mode of transportation the maximum it can bear before people stop taking trips altogether, or choose to drive instead. It’s related to yield management, which maximizes revenue by using a fare bucket system, using time of booking as a form of price discrimination; SNCF uses it on the TGV, and in its writeups for American high-speed rail from 2009, it said it boosted revenue by 4%. In either case, you extract from each passenger the maximum they can pay by making features like “don’t get stuck in traffic” cost extra.

Supply means giving riders incentives to ride the mode of transportation that’s cheaper to provide. In other words, here we don’t assume fixed (or relatively fixed) service provision, but variable service provision and relatively fixed ridership. Trains nearly universally have lower marginal operating costs than buses per passenger-km; in Washington the buses cost 40% more per vehicle-km, and perhaps 2.5 times as much per unit of capacity (Washington Metro cars are long). Using the fare system to incentivize passengers to take the train rather than the bus allows the transit agency to shift resources away from expensive buses, or perhaps to redeploy these resources to serve more areas. If anything, the bus should cost more. There are shades of this line in incentives some transit agencies give for passengers to switch from older fare media to smart cards: the smart card is more convenient and thus in higher demand, but it also involves lower transaction costs, and thus the agency incentivizes its use by charging less.

The network effect means avoiding segmenting the market in any way, to let passengers use all available options. The fastest way to get between two points may be a bus in some cases and a train in others, or a combined trip. This fastest way is often also the most direct, which both minimizes provision cost to the agency and maximizes passenger utility. This point argues in favor of free transfers especially, more so than fare integration. Tokyo fares are integrated in the sense that the different railroads charge approximately the same for the same distance; but transfers are not free, and monthly passes are station to station, with no flexibility for passengers who live between two parallel (usually competing) lines.

The dominant reason to offer integrated fares is network effects, more so than supply. Evidently, I am not aware of transit agencies that charge more for buses than for trains, only in the other direction. That fare integration allows transit agencies to reduce operating costs mitigates the loss of revenue coming from ending price discrimination; it is not the primary reason to integrate fares.

The issue at hand is partly frequency, and partly granularity. A typical transit corridor, supporting a reasonably frequent bus or a medium-size subway station, doesn’t really have the travel demand for multiple competing lines, even if it’s a parallel bus and a rail line. Fare disintegration ends up reducing the frequency on each option, sometimes beyond the point where it starts hurting ridership.

In Washington it’s especially bad, because of reverse-branching. The street network makes it hard for the same bus to serve multiple downtown destinations (or offer transfers to other buses for downtown service). Normally, riders would be able to just take a bus to the subway station and get to their destination, but Washington plans buses and trains separately, so two of the trunk routes, running on 14th an 16th Streets, reverse-branch. The hit to frequency (16-18 minutes per destination off-peak) is so great that even without fare integration it’s worthwhile to prune the branches. But such situations are not unique to Washington, and can occur anywhere.

The required ingredients are a city center that is large enough, or oriented around a long axis, with a street network that isn’t a strict grid and isn’t oriented around the axis of city center. New York is such a city: if it didn’t have fare integration, buses would need to reverse-branch from the north to serve the East Side and West Side, and from anywhere to serve Midtown and Lower Manhattan.

The granularity issue is that there isn’t actually a large menu of options for riders with different abilities to pay. This is especially a problem in American suburbs, with nothing between commuter rail (expensive, infrequent off- and reverse-peak, assumes car ownership) and the bus (in the suburbs, a last-ditch option for people below the poverty line). I wrote about this for Streetsblog in the context of Long Island; there’s also a supply angle – different classes of riders travel in opposite directions, so it’s more efficient to put them on one vehicle going back and forth – but this is fundamentally a problem of excessive market segmentation.

This also explains how Tokyo manages without fare integration between different rail operators. Its commuter rail lines are not the typical transit corridor. With more than a million riders per day (not weekday) on many lines, there is enough demand for very high frequency even with disintegrated fares. A passenger between two competing lines can only get a monthly pass on one, but it’s fine because the one line is frequent and the trains run on time.

The rest of the world is not Tokyo. Branches in Outer London and the Paris suburbs aren’t terribly frequent, and only hit one of the city centers, necessitating free transfers to distribute passengers throughout the city. They also need to collect all possible traffic, without breaking demand between different modes. If RER fares were higher than Metro fares, some areas would need to have a Metro line (or bus line) paralleling the RER, just to collect low-income riders, and the frequency on either line would be weaker.

The demand issue is still real. Fare integration is a service, and it costs money, in terms of lost revenue. But it’s a service with real value for passengers, independently of the fact that it also reduces operating costs. The 99.5% of the world that does not live in Tokyo needs this for flexible, frequent transit choices.

When Buses are a Poor Guide to Corridor Demand, Redux

Generally, the best guide to where a city should build rail lines is where the busiest buses are. However, there are exceptions. I have written two posts about this giving examples of exceptions, and am going to give a third exception; I also intend to write a separate post soon giving a fourth exception.

The first post, from four years ago, deals with cases where the bus alignment has to stay on a major street, but some major destinations are just away from the street; a subway can deviate to serve those destinations. Examples include Old Jaffa in Tel Aviv near the north-south spine of bus lines 1 and 25, and Century City near the Wilshire corridor. Here, buses are a good guide to corridor demand, but the rail line should serve microdestinations just outside the corridor.

The second post, from last year, is more properly about corridors. It describes street networks that are hostile to surface transit, by featuring narrow, meandering streets. The main example is Boston, especially the Green Line Extension, in a rail right-of-way in a city infamous for its labyrinthine streets. Another example is the Evergreen extension in Vancouver, serving Coquitlam; the bus the extension replaced, the 97-B, meandered through Coquitlam since the streets were so poorly configured, while the extension uses a short tunnel and runs parallel to a railroad.

In this post I’d like to expand on a point I made, obliquely, in the Voice of San Diego. In San Diego, there’s an under-construction light rail extension, in a rail right-of-way, into an area with not-great bus ridership. Consult the following map:

Preexisting light rail (“Trolley”) is in black, the extension (of the Blue Line) in blue, the parallel north-south arterial in purple, and two buses in green and red. The bus ridership on Ingraham is very low: the bus route running on it, 9, has 1,500 riders per weekday (source). The top bus in San Diego, the 7 (going north of downtown, then east), has 11,000. So on the surface, this suggests there isn’t much demand for north-south transit in that area of the city, called Pacific Beach.

But that’s wrong, because in an auto-oriented city like any US city except New York, the major streets are determined by car access. The relentless grids of so many North American cities – Chicago, Los Angeles, Toronto, Vancouver – are not just where the buses go, but also where the cars go. Even in Manhattan, if you have the misfortune to find yourself going east-west in a car, you will probably use one of the major two-way streets, like 14th or 42nd, which are less clogged than the one-way streets in between. Non-gridded street networks for the most part obey this rule too – the commercial streets tend to be the wider ones used by car through-traffic.

Freeways throw a wrench into this system. They offer a convenient route for cars, but are abominable for commerce. Locations 5 minutes by car from the freeway are good; locations right along the freeway are not, unlike ones right along an arterial road. The main car route from Pacific Beach to the CBD is taking an east-west arterial to the I-5, not going south on Ingraham. This means that the demand for north-south traffic actually shows as strong commerce on east-west streets, hosting bus routes 27 and 30, and not on Ingraham. The 27 has weak ridership, and the 30 has strong ridership but not right along the I-5. But in a sense it doesn’t really matter, because, like the car- and bus-hostile narrow streets of old city centers, the freeway-centric road network in that part of San Diego suppresses bus ridership relative to future rail ridership.

In the presence of rail, the strong routes are the ones orthogonal to the rail line. Here, the 27 and 30 already preexist; there is a planned Trolley stop at the intersection with the 27, and presumably the 30 will be rerouted to serve that intersection rather than to duplicate the trains along the freeway. (I tried talking to the transit agency about this, but didn’t get any useful answers.) So the decent east-west bus ridership in Pacific Beach is actually an argument in favor of a north-south rail extension.

Like every exception to a general rule, this is not a common scenario. So where else are there cases where this special case holds? The necessary elements are,

  1. The city must be auto-oriented enough that car access is crucial to nearly all commercial drags. In Paris, it doesn’t matter how you reach the Peripherique by car, because car ownership is so low.
  2. The city should not have a strong mainline rail network, which leads to a hierarchical transit network (buses feeding train stations), in which both buses and cars use the same major streets to reach train stations. This means that Sydney and Melbourne are out, as are German cities short of Berlin and Munich’s transit mode shares.
  3. The city must have a strong network of urban freeways, disrupting the street network to the point of siphoning traffic away from the surface streets that would otherwise be the main routes.

As it happens, all three elements are present in Tel Aviv. North-south travel within the region uses Ayalon Freeway, inconveniently east of the traditional city center; the city has been building a CBD closer to the freeway, but it’s still not quite there. This suggests that traffic is suppressed on the north-south arterials to the west – Ibn Gabirol (hosting the planned second line of the subway) and Dizengoff (possibly hosting the third) – is suppressed, and those streets require subways. This is in part why, before the Red Line began construction, I argued in favor of putting a north-south subway under Ibn Gabirol, and not under freeway-adjacent Namir Road, where the Red Line goes.

In the future, this pattern suggests that Tel Aviv should make sure to build north-south subways under Ibn Gabirol and Dizengoff, and extend them north. The significance of the northern direction is that the effect I’m describing in this post only works when car ownership is high; Israel is poor enough that car ownership is not universal, and in the poorer southern suburbs it is low enough that the buses do give a good guide to corridor demand, whereas in the northern suburbs everyone owns a car. There is likely to be suppressed transit demand in Herzliya, Ramat HaSharon, and northeastern Tel Aviv (including Ramat HaHayal, an edge city with many tech jobs). Thus ridership on a subway line going elevated over Sokolov in Ramat HaSharon and Herzliya, or on Raoul Wallenberg to Ramat HaHayal, is likely to be higher than present-day bus ridership suggests.

An American example is Washington’s suburbs. The Metro extensions are planned with little regard for bus ridership. While the Silver Line is bad for multiple reasons – high construction costs, service to too far exurbs, too much branching on an overloaded trunk – the extension to Tysons Corner is its one good aspect. There is no point in discussing bus ridership at an edge city like Tysons – conventional buses wouldn’t be following the same route that the cars follow, and freeway express buses almost universally have trivial ridership.

Finally, Vancouver. While Vancouver itself is gridded, its suburbs are much less so. In the suburbs served by the Trans-Canada Highway, especially Surrey, it’s likely that car traffic mostly follows roads feeding the highway. People drive to their jobs in Downtown, Central Broadway, Metrotown, or any of Surrey’s internal centers; there aren’t a lot of park-and-rides at SkyTrain stations, which instead emphasize transit-oriented development, and in Surrey there are actually more park-and-ride spaces at the freeways, with express bus access, than at the one SkyTrain stop with parking, Scott Road. This suggests that there is suppressed bus ridership in Surrey and Langley parallel to the Trans-Canada, along Fraser Highway. Extending SkyTrain in that direction is on a distant priority list for the region, and this theory suggests that it should be moved up, to be just behind the Broadway subway to UBC.

Future Los Angeles Metro Investments

I just put up an article on Urbanize complaining about Los Angeles’s uniquely high operating costs on the subway and light rail. In the article, I offered a few explanations, but also said that none of them seems satisfying: high wages (wages are as high in Chicago), low frequency (frequency is as low in Atlanta), low train operator efficiency (the gap with London is too small), few lines with two different technologies (Atlanta has just two lines and Miami one).

Long-time readers may be used to my sneering at American transit operations for being primitive compared with European ones, but here, the best American system (Chicago) outperforms the four Western European systems for which I have data, and one more (Philadelphia) is within those four European systems’ range. Per car-km, Chicago spends $5 in operating costs, London/Paris/Berlin $6, Philadelphia and Madrid $7, New York $9-10, and Los Angeles $12.

So Los Angeles is special. Lisa Schweitzer suggests my discounting the frequency and system size explanations is in error, and when I brought up Atlanta on social media, she noted that Atlanta’s labor costs are lower than Los Angeles’s. Assuming this is correct (Southern California uniquely combines high nominal wages with a tiny subway network), Los Angeles should expect subway operating costs to come down as it builds its urban rail network. Some lines, like the Regional Connector, the Wilshire subway, and the Crenshaw light rail line, are already under construction. But as the system grows (especially the subway system, which is technologically incompatible with the light rail lines, even the fully grade-separated Green Line), average operating costs will fall, which suggests that marginal operating costs are low. If Los Angeles has not figured this into its calculation, this means that the finances of future subway lines are better than projected.

I drew this map of what rapid transit Los Angeles should build. The map isn’t new, but I want to use it to explain how I think cities should be building subways.

1. Every line is rapid transit, even lines built out of light rail lines today, like the Blue Line and the Expo Line. Unprotected grade crossings and street running, even in dedicated tracks, limit capacity and reliability elsewhere down the line, even though they do not reduce speed on other segments of the line. The Orange Line is replaced by a subway, not light rail.

2. Branching is rare. Only three subway lines branch. Two tunnel through Sepulveda Pass (where Let’s Go LA suggests four branches on each side of the tunnel), with each line branching into two in the north, in the Valley, where demand on each corridor is lower. The third is on Vermont, with a branch west to Torrance.

3. Many lines run elevated, in less dense areas with very wide streets. South Vermont is this south of Gage. This also includes the four north-south lines in the San Fernando Valley heading from the Sepulveda tunnel.

4. There are three distinct regional rail lines, all electrified, with two through-running; the branch to the airport is elevated. One branches, the others don’t. Local and express trains could happen, but the acceleration and reliability boosts from electrification are so great that speeds in the 70-80 km/h range are possible even with all the infill stops. The line to LAX could also host some intercity trains, provided it has four tracks. The dark blue line, labeled the I-5 line, should have four tracks at the very least on the shared segment, and likely longer, for planned high-speed rail; some of the work is already being done, but there is still going to be track sharing with freight trains.

5. The system is really a hybrid of a typical radial rail system and a grid, like the Mexico City Metro. There are fifteen lines, including commuter rail; eight, including the commuter lines, serve the CBD. Some (the Pink, Orange, and Atlantic Lines, and the southern half of the Green Line) are fully circumferential, the others (Harbor/Azure, Red, Crenshaw/Brown) serve secondary CBDs and try to avoid being too much like bad combinations of radial and circumferential transit. The reason for this structure is that Los Angeles has very strong secondary centers, including Century City, Burbank, El Segundo, Santa Monica, and Koreatown.

6. Much of the system assumes reasonable upzoning, for example the northern extension of the West Santa Ana/Lime Line to La Crescenta and Sun Valley. This includes replacing single-family zoning with multifamily zoning everywhere, and building up CBDs at major connection points such as Vermont/Wilshire and El Segundo.

7. There is a lot of service in LA County, but not much in the other counties except lines to the CBD. It’s possible to build up a fuller system in Orange County, extending the Purple Line east and also adding some grid routes, assuming extensive residential upzoning everywhere and commercial upzoning in Santa Ana, Anaheim, and the beach cities.

8. At LA construction costs (about $400-500 million per km underground), the entire map should be doable for maybe $90 billion; at reasonable costs, make it $40 billion. LA is spending comparable amounts of money on transportation out of the recent ballot measures, it just spends a lot of it on operational waste, on BRT (the current plans for Vermont are BRT, even though the corridor is busy enough to deserve a subway), or on roads.