Safer Streets: Design is Better Than Enforcement

As some American cities are attempting to reduce the number of car accident fatalities, under the umbrella of Vision Zero, the growing topic is one of traffic enforcement. Streetsblog has long documented many instances in which the police treats any case in which a car runs over a pedestrian as a no-fault accident, even when the driver was committing such traffic violations as driving on the sidewalk. In addition to enforcement, there’s emphasis on reducing the speed limit in urban areas, from 30 to 20 miles per hour, based on past campaigns in Europe, where speeds were reduced from 50 km/h to 30. Unfortunately, street design for lower speeds and greater traffic safety has taken a back seat. This is not the best way to improve street safety, and is not the standard practice in the countries that have reduced car accident rates the most successfully, namely the UK and the Scandinavian countries.

On high-speed roads, one of the most important causes of fatal accidents is the combination of driver fatigue and sleepiness. For some studies on this problem, see here, here, and here. The second link in particular brings up the problem of monotony: if a road presents fewer stimuli to the driver, the driver is more likely to become less vigilant, increasing the probability of an accident. One study goes on and shows that higher speed actually increases monotony, since drivers have less time to register such stimuli as other cars on the road, but this was obtained in controlled conditions, and its literature review says that most studies find no effect of speed. I emphasize that this does not mean that lower speed limits are ineffective: there’s evidence that reducing highway speed limit does reduce accident rates, with multiple studies collected in a Guardian article, and lower accident rates in France since the state installed an extensive system of speed cameras.

But while speed limit reductions offer useful safety benefits, it is important to design the roads to be slower, and not just tell drivers to go slower. Road monotony is especially common in the United States; per the second study again,

While comparing self-reported driving fatigue in the US and Norway, Sagberg (1999) suggests that the higher prevalence of self reported drowsy driving found in the US may be due to differences in road geometry, design and environment, as well as exposure. He argues that the risk of falling asleep is higher on straight, monotonous roads in situations of low traffic, where boredom is likely to occur. This type of roads is more common in the US than in Norway.

The studies I have consulted look primarily at highways and rural roads; I have not found comparable literature on urban roads, except one study that, in a controlled simulation, shows that drivers are better at gauging their own alertness levels on urban arterials than on rural roads. That said, urban arterials share many design traits that lead to monotony, especially in the United States and Canada:

  • They are usually straight, forming a grid rather than taking haphazard routes originating from premodern or early-industrial roads.
  • They are wide: 4-6 lanes at a minimum, often with a median. Lanes are likely to be wide, closer to 3.7 meters than the more typical urban 3 meters.
  • Development on them usually does not form a strong enclosure, but instead commercial developments are only 1-2 stories, with setbacks and front and side parking lots.

Such roads are called stroads in the language of Charles Marohn, who focuses on issues of their auto-centric, pedestrian-hostile nature. Based on the studies about monotony, I would add that even ignoring pedestrians entirely, they are less safe than slower roads, which prime drivers to be more alert and to speed less. It is better to design roads to have more frequent stimuli: trees, sidewalks with pedestrians, commercial development, residential development to the extent people are willing to live on top of a busy road.

Regarding lane width, one study finds that roads are the safest when lanes are 3-3.2 meters wide, because of the effects of wider lanes on driver speeds. A CityLab article on the same subject from two years ago includes references to several studies that argue that wide lanes offer no safety benefit for drivers, but are hostile to pedestrians and cyclists.

This approach, of reducing speed via road design rather than enforcement, is common in Scandinavia. Stockholm has a few urban freeways, but few arterials in the center, and many of those arterials have seen changes giving away space from cars to public transit and pedestrians. Thus, Götgatan is partly pedestrianized, and Odengatan has center bus lanes and only one moving car lane in each direction; the most important of Stockholm’s streets, Sveavägen, has several moving car lanes in each direction, but is flanked on both sides by medium-rise buildings without setbacks, and speeds are rarely high.

When enforcement happens, the great successes, for example in France under the Sarkozy administration, involve automation. Red light cameras have a long history and are controversial, and in France, Sarkozy lowered the speed limits on many roads and stepped up speed camera enforcement. The UK has extensive camera enforcement as well. Human enforcement exists, but is less common than speed cameras. Thus, the two main policy planks Vision Zero should fight for in the US are,

  1. Road redesign: narrower lanes, wider sidewalks, trees, and dedicated bus and bike lanes in order to reduce the number of car lanes as well as provide more room for alternatives. Zoning laws that mandate front setbacks should be repealed, and ideally so should commercial height limits on arterials. In central cities, some road segments should be closed off to cars, if the intensity of urban activities can fill the space with pedestrians.
  2. Lower speed limits in the cities, enforced by cameras; fines should be high enough to have some deterrent effect, but not so high that they will drive low-income drivers bankrupt.

It is especially important to come up with solutions that do not rely on extensive human enforcement in the US, because of its longstanding problem with police brutality and racism. The expression “driving while black” is common in the US, due to bias the police in the US (and Canada) exhibits against black people. In Europe, even when bias against certain minorities is as bad as in the US, overall police brutality levels are lower in the US by factors ranging from 20 to 100 (see for example data here). In my Twitter feed, black American urbanists express reluctance to so much as call the police on nonviolent crime, fearing that cops would treat them as suspects even if they are the victims. When it comes to urban traffic safety – and so far, Vision Zero in the US is an urban movement – this is compounded by the fact that blacks and other minorities are overrepresented in the cities.

This means that, in the special conditions of US policing, it’s crucial to prevent Vision Zero from becoming yet another pretext for Driving While Black arrests. As it happens, it does not require large changes from best practices in Europe, because those best practices do not involve extensive contact between traffic police and drivers.

Recall last year’s post by Adonia Lugo, accusing Vision Zero of copying policy from Northern Europe and not from low-income American minority communities. As I said a year ago, Adonia is wrong – first in her belief that foreign knowledge is less important than local US knowledge, and second in her accusation that US Vision Zero advocates copy European solutions too much. To the contrary, what I see is that the tone among US street safety advocates overfocuses on punitive enforcement of drivers who violate the speed limit or break other law. Adapting a problem that in Europe is solved predominantly with street design and technology (speed cameras don’t notice the driver’s skin color), they instead call for more policing, perhaps because mainstream (i.e. white) American culture is used to accepting excessive police presence.

When Through-Running Is Inappropriate

I support through-running of regional trains: as far as possible, trains should not terminate in major city centers, but instead run through to urban neighborhoods and suburbs on the other side of the CBD. My first blog posts made this point about New York, and over the years I’ve written about this in the contexts of New York, Boston, Washington, Chicago, and Tel Aviv. However, in secondary cities, through-running is not always appropriate policy. If a city is near the edge and not at the center of its metro area, then quite often it’s preferable to run a separate service, which may overlap the primary city’s regional rail system. In some cases, through-running is actively harmful; unfortunately, this is currently done in San Jose and Providence.

Theory

Consider the following example city:

throughrunexample

The metro area lies on an east-west rail line, and consists of a central city several suburbs; higher-density areas are denoted by darker shades, with the primary CBD in the darkest shade. The city proper also has five secondary CBDs, two of which are on the rail line. On the west, one suburb, really a secondary city, is larger than the rest, and has its own CBD, as job-dense as one of the primary city’s secondary CBDs. With rough symmetry of suburban demand west and east, there is no good reason why trains should not through the primary CBD, and good reasons why they should:

  • People in the eastern suburbs may work in the secondary CBD just west of the primary one, and people in the western suburbs may work in the secondary CBD just east of the primary one.
  • The primary CBD may not have room to park trains at rush hour without a costly railyard expansion.
  • People within the central city may use the line as a rapid transit trunk, to get to either the primary CBD or the two secondary CBDs on the line, as well as to residential neighborhoods not depicted in the diagram.

This is relatively uncontroversial – urban transit is designed along the same guidelines. Also uncontroversial is the question of how far east the commuter line should run: the diagram shows a string of medium-size suburbs, so the line should run as far as the easternmost one, potentially with short-turn runs if the trains at the end are too empty.

The real controversy is how far west to run the service. On the one hand, the secondary city provides a natural outer anchor, with some reverse-peak ridership potential, so there’s an argument for terminating service there. I have criticized the Human Transit model of anchoring as a matter of urban planning, but as a matter of transit planning with fixed urban layout, it is sound; see explanations here and here. On the other hand, there are two smaller suburbs farther west, where people might want to commute to either the primary city or the secondary one, so perhaps service should run farther, with many trains short-turning at the secondary city to avoid running too many empty trains at the western end.

Which of the two options is better – terminating services at the secondary city or continuing onward – depends on the frequency the trunk rail line can support. The reason is that continuing onward requires a very large drop in capacity to avoid empty trains. In the depicted diagram, in relative units, 10% of the western suburbs’ built-up residential area is west of the secondary city; maybe another 10% is the western areas of the secondary city, which could host a station in addition to that at the city’s center. This means that nearly all trains should short-turn; only perhaps one in three or four should continue. If the demand is so intense that a quarter of the base frequency is enough, then trains should continue. But most likely, it isn’t. An individual commuter line with a train every 10 minutes off-peak would be stepped down to every half an hour at the western end, which is borderline; a train every 10 minutes off-peak almost never happens outside Paris, Tokyo, and other enormous systems, except when multiple branches interline to a single trunk.

The alternative is to terminate commuter trains at the secondary city, but then run supplemental service, centered at the secondary city. This supplemental service is not supposed to serve demand into the primary city, handling supercommuters from the western end via a timed transfer (with possible peak through-service), so it can run shorter trains at higher frequency. Sometimes, the secondary city’s CBD must be judged too auto-oriented to be served with commuter rail, and then the correct service pattern is no trains at all west of the secondary city.

Examples

In both Providence and San Jose, a situation akin to the above diagram occurs, except without any through-service beyond the primary CBD (respectively, Boston and San Francisco). Of course, San Jose has more residents than San Francisco, 1.03 million compared with 870,000, but it has only 360,000 jobs to San Francisco’s 610,000. Moreover, San Jose’s employment is more dispersed; according to OnTheMap, its CBD’s job density is about comparable to that of Providence’s CBD. Evidently, Caltrain ridership is 13,600 per weekday at San Francisco and 4,200 at San Jose Diridon (PDF-p. 6 here), with both stations located somewhat away from their respective cities’ CBDs. A proper comparison of Providence to Boston is harder to make, since South Station has multiple line and not just the Providence Line, but Providence’s secondary role within New England is well-understood.

In both cities, service runs beyond the secondary city, at reduced frequency. Between San Francisco and San Jose, Caltrain runs 5 trains per hour at the peak, and a train every hour off-peak; but Caltrain also runs three trains per day in each direction south to Gilroy, 47 km to the south (San Francisco-San Jose is 77 km). Between Boston and Providence, a distance of 70 km, the MBTA runs 3-4 trains per hour at the peak and a train every 1.5-2 hours off-peak, but one train per hour at the peak and one train every four hours off-peak continues another 31 km south to Wickford Junction.

Both tails, to Gilroy and to Wickford Junction, are significant drags on the ability of their respective cores to modernize. Ridership is very low: Tamien, just south of San Jose Diridon, has 1,100 weekday riders, but the sum total of all the stations to its south is 559; the two stations south of Providence have between them 454 weekday riders, compared with about 2,300 at Providence and 20,000 on the Providence Line overall (see PDF-pp. 74 and 77 of the 2014 MBTA Bluebook). In both cases, low ridership is a cause of poor service rather than a consequence: Clem Tillier tallied the population and job densities near each Caltrain station and found that, except in the southern neighborhoods of San Jose, there is no real ridership potential on the Gilroy extension; a similar analysis of the Providence Line’s tail has not been carried out, but one of its two stations is in a low-density suburb without many Boston-bound commuters, while Wickford Junction is surrounded by undeveloped land. Caltrain is currently planning to electrify south to Tamien, but there is no justification for continuing electrification further, which means that maintaining Gilroy service would require mixing diesel locomotive-hauled trains with lightweight EMUs; moreover, south of Tamien, the tracks are owned by Union Pacific rather than by Caltrain, and UP has little interest in allowing modern passenger trains on its tracks. In Rhode Island, an additional complication is that the line from Providence down to Wickford Junction is prime high-speed rail territory, and commuter rail ridership is frankly too low to justify complex scheduling with multiple overtakes, unlike the situation farther north in Massachusetts.

In the Bay Area, there is little that can be done, due to the low potential ridership south of Tamien, San Jose’s suburban layout and the distance of Diridon from the CBD, and UP ownership of the tracks. Perhaps a few diesel trains could run to San Jose Diridon with timed transfers to the electrified line from Tamien to San Francisco, but quite likely service could just be canceled. In Rhode Island, Wickford Junction should probably be closed due to low ridership, but Peter Brassard proposed an alternative, a Providence-focused line running short trains at medium frequency (perhaps once every 15 minutes), with very short interstations in order to serve Providence neighborhoods and not just the CBD. Such a line, running at the same average speed as a freight train due to the frequent stops, would interfere heavily with intercity trains, which means that four-tracking the line is a necessary precondition, as discussed here, but this may be worth it given potential local ridership. The most constrained part of the right-of-way is alongside the Route 10 expressway, which requires considerable repairs and is currently being overhauled at high cost.

Amtrak’s Rolling Stock Order: Followup

A year ago, based on a leak from Senator Charles Schumer’s office, I attacked Amtrak for paying double for its new high-speed trains – $2.5 billion for 28 trainsets, about $11 million per car. Amtrak at the time denied the press release, saying it was still in the process of selecting a bidder. However, last week Amtrak announced the new order, confirming Schumer’s leak. The trainsets are to cost $2 billion, or $9 million per car, with an additional $500 million spent on other infrastructure. The vendor is Alstom, which is branding all of its export products under the umbrella name Avelia; this train is the Avelia Liberty.

You can see a short promotional video for the trains here and read Alstom’s press release here. Together, they make it obvious why the cost is so high – about twice as high per car as that of Eurostar’s Velaro order, and three times as high as that of the shorter-lived N700 Shinkansen. The Avelia Liberty is a bespoke train, combining features that have not been seen before. Technical specs can also be seen in Alstom’s press kit. The Avelia Liberty will,

  • Have a top speed of 300 km/h.
  • Have articulated bogies.
  • Be capable of 7 degrees of tilt, using the same system as in Alstom’s Pendolino trainset.

In particular, the combination of high speed and high degree of tilt, while technically feasible, does not exist in any production train today. It existed in prototype form, as a tilting TGV, but never made it to mass production. The Pendolino has a top speed of 250 km/h, and the ICE-T has a top speed of 240 km/h. Faster tilting trains do not tilt as much: Talgo claims the Talgo 350 is capable of lateral acceleration of 1.2 m/s^2 in the plane of the train, which corresponds to 180 mm of cant deficiency, achievable with 2-3 degrees of tilt; the tilting Shinkansen have moderate tilting as well, which the JRs call active suspension: the N700 tilts 1 degree, and appears capable of 137 mm of cant deficiency (270 km/h on 2.5 km curves with 200 mm cant), whereas the E5 and E6 tilt 2 degrees, and appear capable of 175 mm (in tests they were supposed to do 360 km/h on 4 km curves with 200 mm cant, but only run at 320 km/h for reasons unrelated to track geometry).

I have argued before, primarily in comments, that a train capable of both high speed and high degree of tilt would be useful on the Northeast Corridor, but not at any price. Moreover, the train is not even planned to run at its advertised top speed, but stay limited to 257 km/h (160 mph), which will only be achievable on short segments in Massachusetts, Rhode Island, and New Jersey. Amtrak has no funded plan to raise the top speed further: the plans for constant-tension catenary in New Jersey are the only funded item increasing top speed. There is no near-term plan on the horizon to obtain such funding – on the contrary, Amtrak’s main priority right now is the Gateway tunnel, providing extra capacity and perhaps avoiding a station throat slowdown, but not raising top speed.

Running trains at 300 km/h on the segments that allow the highest speeds today, or are planned to after the speedup in New Jersey, would save very little time (75 seconds in New Jersey, minus acceleration and deceleration penalties). Making full use of high top speed requires sustaining it over long distances, which means fixing curves in New Jersey that are not on the agenda, installing constant-tension catenary on the entire New York-Washington segment and not just over 40 km of track in New Jersey to eliminate the present-day 215 km/h limit, and building a bypass of the entire segment in southeastern Connecticut along I-95. None of these is on the immediate agenda, and only constant-tension catenary is on the medium-term agenda. Hoping for future funding to materialize is not a valid strategy: the trains would be well past the midpoint of their service lives, and spend many years depreciating before their top speed could be used.

What’s more, if substantial bypasses are built, the value of tilting decreases. In advance of the opening of the Gotthard Base Tunnel, Swiss Federal Railways (SBB) ordered 29 trainsets, without tilting, replacing the tilting Pendolino trains that go through the older tunnel. SBB said tilting would only offer minimal time reduction. The eventual cost of this order: about $36 million per trainset as long as 8 US cars. On the entire Northeast Corridor, the place where tilting does the most to reduce travel time is in Connecticut, and if the eastern half of the tracks in the state are bypassed on I-95, tilting loses value. West of New Haven, tilting is not permitted at all, because of Metro-North’s rules for trains using its tracks; on that segment, tilting will always be valuable, because of the difficulty of finding good rights-of-way for bypasses not involving long tunnels, but to my knowledge Amtrak has not made any move to lift the restriction on tilting. Even with the restriction lifted, a 300+ km/h train with moderate tilting, like the N700 or E5/6 or the Talgo AVRIL, could achieve very fast trip times, with only a few minutes of difference from a hypothetical train with the same top speed and power-to-weight ratio and 7 degrees of tilt. It may still be worth it to develop a train with both high speed and a high degree of tilt, but again, not at any cost, and certainly not as the first trainset to use the line.

Another issue is reliability. The Pendolino tilt system is high-maintenance and unreliable, and this especially affects the heavier Acela. SBB’s rejection of tilting trains was probably in part due to the reliability issues of previous Pendolino service across the Alps, leading to long delays. Poor reliability requires more schedule padding to compensate, and this reduces the advantage gained from faster speed on curves. While tilting trains are overall a net positive on curvy routes like the Connecticut segment of the Northeast Corridor, they are probably not useful in any situation in which 300 km/h top speeds are achievable for a meaningful length of time. This goes double for the Avelia Liberty, which is not a proven Pendolino but a new trainset, sold in a captive market that cannot easily replace it if there are maintenance issues.

In my post a year ago, I complained that Amtrak’s specs were conservative, and did not justify the high cost. I stand behind that assessment: the required trip times are only moderate improvements over the current schedule. At least between New York and Boston, the improvement (9 minutes plus stop penalty at New London) is less than the extent of end-of-line schedule padding, which is at least 10 minutes from Providence to Boston for northbound trains. However, to achieve these small trip time improvements, Amtrak elected to demand exacting specs from the trainsets, leading to high equipment costs.

In 2013, I expounded on this very decision by borrowing a Swiss term: the triangle of rolling stock, infrastructure, and timetable. Planning for all three should be integrated. For example, plans for increases in capacity through infrastructure improvements should be integrated with plans for running more trains, with publicly circulated sample schedules. In this case, the integration involves rolling stock and infrastructure: at low infrastructure investment, as is the case today, there is no need for 300 km/h trainsets, whereas at high investment, high top speed is required but 7-degree tilt is of limited benefit. Instead of planning appropriately based on its expectations of near-term funding, Amtrak chose to waste about a billion dollars paying double for trainsets to replace the Acela.

Buses Versus Trams: Low-Floor Boarding

For years, Jarrett Walker has been making the point that streetcars do not provide much transportation value over buses. They have higher capacity, because trams can run longer vehicles, but on a medium-ridership bus line without capacity constraints, this is not relevant. As I note in comments, tramways can use rail signaling to get marginal speed advantages, but it’s not a big advantage. They also have slightly lower minimum headways – a single bus route running more often than every 3 minutes will hopelessly bunch, whereas tramways seem capable of higher frequency – but this is again a matter of capacity. And yet, there is an observed rail bias, even when other factors are kept the same: a Transportation Research Bureau report by Edson Tennyson concludes it is 34-43%, using evidence from North American cities in the four decades after WW2. In this post, I would like to propose one mechanism that may produce rail bias even when speed, capacity, and frequency are unchanged.

Low-floor vehicles make it easier to board from raised curbs. Passengers do not need to climb steps as they do on older buses and streetcars, but can walk straight to the vehicle. This speeds up boarding and improves the passenger experience: see p. 14 of a presentation about commuter rail level boarding, p. 64 of a book about low-floor light rail, and a study about bus dwell times in Portland. It’s especially useful for passengers in wheelchairs: as the Portland bus reference notes, the difference between low- and high-floor buses’ dwell times is especially noticeable when there are wheelchair lifts, because operating a wheelchair lift on a low-floor bus is much faster than on a high-floor bus. Low-floor vehicles’ ability to not lose too much time every time a disabled passenger boards or disembarks improves reliability, which in turns allows schedules to be less padded, improving trip times even when no passenger in a wheelchair uses the route.

While high-floor buses and high-floor trains serving low platforms are similar in requiring passengers to climb multiple steps, low-floor buses and trains with level boarding (regardless of whether high or low) are different. Trains run on guideways; they can have the vehicle’s edge exactly level with the platform edge, with narrow horizontal gap. My attempt to measure this on SkyTrain in Vancouver yielded a horizontal gap of about 5 cm, and a vertical gap of perhaps 2 cm; with such gaps, passengers in wheelchairs can board unaided. While SkyTrain is automated rapid transit rather than light rail, nothing about its technology makes the rail-platform gap easier to resolve than on other rail lines.

In contrast, low-floor buses do not have true level boarding. The bus floor is still raised from the curb somewhat, so modern low-floor buses typically kneel, increasing dwell time by a few seconds per stop, to reduce the platform gap. While it’s possible to raise the curbs as at light rail stops, the buses are still buses, and cannot align themselves to be as close to the platform as trains are: without rails, they sway from side to side, so a safety margin is required from the platform edge. As a result, passengers in wheelchairs cannot board unaided without a retractable ramp, which adds considerable dwell time. On board the bus, the more sudden acceleration also requires the wheelchair to be strapped, adding dwell time even further.

Because there is no way to prevent a bus from incurring schedule risk if there’s a passenger in a wheelchair, bus schedules are inherently more vulnerable than train schedules. While few transit passengers are in wheelchairs, passengers who have luggage, walkers, or strollers can get on and off much faster when there’s perfect level boarding, and are slowed by the need to navigate steps or a wide vehicle-platform gap; the schedule will have to take this into account. Low-floor buses reduce this problem, but do not eliminate it.

The limiting factor to bus frequency is not stopping distances, unlike the case of trains. Instead, it is bunching: at very high frequency, small variations in boarding time compound, as fuller buses are harder to board. Soon enough a slightly delayed bus becomes even more delayed as passengers take more time to board, until it bunches with the bus behind it. This effect can be reduced with off-board fare collection, but when the bus is crowded, the combination of narrow passageways and a significant platform gap means that boarding time is nontrivial no matter what.This effect means that all else being equal, a low-floor tramway will be faster and more reliable than a low-floor bus. In practice, all else is not equal, and in particular, in mixed traffic, the bus’s ability to get around obstacles will make it faster. But with well-enforced dedicated lanes, tramways are capable of running reliably with less schedule padding than buses. A familiar experience to North American bus riders – sitting for several minutes as a passenger in a wheelchair boards, and maneuvers awkwardly through the narrow spaces to where the bus driver will strap in the chair – is not an issue on any train with level boarding.

Mixing Circumferential and Radial Transit in the Other Direction

Two years ago, I wrote a post criticizing subway lines that mix radial and circumferential elements. These lines, for examples Shanghai Metro Lines 3 and 6 and New York’s G train before 2001, contain long radial segments, going from an outlying neighborhood toward city center, but then switch to circumferential mode, avoiding city center and instead serving secondary nodes. Such lines do not get high ridership, because they fail at either radial or circumferential transit. Recently, I was challenged in comments about my support for a mixed line that goes in the other direction: circumferential on the outside, radial on the inside. I would like to talk more about such lines.

Consider the following diagram of a subway system:

subwaydiagram

The city is shown in light gray, with its center in dark gray. There are five subway lines: the red and blue lines are straightforward radials, the green line is a straightforward circumferential, the yellow line mixes radial and circumferential as criticized in my previous post, the pink line mixes radial and circumferential in the other manner, which I will describe in this post.

The reason the yellow line is going to underperform in this system is that it fails as a radial: it does not go to city center, which has the largest concentration of destinations for transit users. People who have equal access to the red and yellow lines, north and south of city center, are much likelier to choose the red line, which takes them where they want to go. The green line fails as a radial too, but has the positive features of a circumferential: it only serves relatively nearby neighborhoods, which are likely to be denser and produce more riders per unit length; it connects to every line in the system; it allows people to connect between two radial lines without going through the congested city center; it has no dominant direction at the peak, so trains are unlikely to be full in the peak direction and empty in the reverse-peak direction. The yellow line has none of these features, unless one wants to connect between the western legs of the blue and pink lines.

The pink line still works as a radial. Its northeastern leg is a straightforward radial, but even its southwestern leg  works as a radial for people who live west of the yellow line and wish to commute to city center. In this way, it is not truly a mixture of radial and circumferential elements the way the yellow line is, but is simply a radial with a circumferential element tacked on at the end.

Whether the pink line’s circumferential tail works must be evaluated against two alternatives: build nothing, and build a radial leg. This is because in an incrementally-built transit system, the radial parts of the line are typically built first, and the circumferential tail is tacked on as a later extension. In the no-build case, the pink line’s southwestern leg would simply be shorter than the other radial legs in this system. In the radial case, the pink line’s southwestern leg would look symmetric with the northeastern leg. This depends on the following factors:

  1. The strength of the radial alternative. If the radial alternative is strong, then this discourages building the circumferential extension, and vice versa. The radial alternative can be weak in several ways: the southwestern quadrant of the city depicted above may be already replete with radial transit and not need more; the population density in the neighborhoods that would be served by the radial option may be low; and the city’s layout may not be the above-depicted perfect circle, so that there is nowhere for the line to turn except sideways.
  2. The strength of the corridor that would be served by the circumferential leg. The leg can never be a complete circle, so it must be evaluated as a rapid transit line on an individual street or corridor. This far out of city center, transit demand on each route is unlikely to be high, but there may well be exceptions, for example if there is a linear secondary CBD. For example, while Seoul Metro Line 2 is fully circumferential, one of its segments follows a Tehran Avenue, a major street in Gangnam with high transit demand, which would justify a subway even if it weren’t part of a large circle.
  3. The strength of the circumferential transit demand from the end of the potential circumferential extension to the radial segment. In the depicted city, there may be strong demand for east-west transit south of the CBD, and the circumferential pink line is then better at serving it than connecting between the red and yellow lines via the blue line.

The original impetus for this post, as noted at the beginning, is a comment challenging me for my support of an extension of Second Avenue Subway Phase 2, going under 125th Street from the planned terminus at Lexington Avenue to Broadway, with stations at the intersection with each preexisting subway line. I contend that in this case, all three factors above point to a very strong circumferential extension. In order:

  1. The radial alternative is to extend Second Avenue Subway to the north, to the Bronx, presumably under Third Avenue, but according to some railfans also under University Avenue. This is problematic, for three reasons. First, the Bronx already has many north-south lines feeding into Manhattan trunk lines, with mediocre ridership. The Manhattan trunk lines are overloaded, but mostly with traffic coming from the Upper East and West Sides, Harlem, and Washington Heights. Second, Third Avenue is close to the Harlem Line, which could be used for local transit if fares and schedules are integrated with the subways and buses. And third, the plan for Second Avenue Subway is for the line to turn west at 125th toward Lexington, since 125th and Second is not as compelling a destination, and this makes it easier to extend the line to the west than to the north.
  2. 125th Street is a very busy street, and acts as the main street of Harlem. Transit demand is high: four bus routes use the street, with a total of 32,630 boardings per weekday on 125th Street, exclusive of other segments of those routes. This count misses people who board elsewhere and get off on 125th, but conversely assigns people who board on 125th and get off elsewhere to this street and not the other segment. But with this caveat in mind, this points to about 11,000 weekday riders per route-km, ahead of New York’s busiest bus per unit length (the M86, with about 7,000), and not far behind the subway average (15,000). This is despite the fact that, in my experience going between Columbia and the Metro-North station at Park Avenue, those buses are not faster than walking.
  3. East-west transit in Uptown Manhattan consists of Pokey-winning crosstown buses; the 125th Street buses are as slow on 125th. An underrated feature of Second Avenue Subway Phase 1 is that it will soon enable a two-seat subway ride from the Upper East Side to the Upper West Side, West Harlem, and Washington Heights. However, this option will require connecting at Times Square, and is useful mainly for people in the southern areas of the Upper East Side connecting to the 1/2/3 rather than to the A/B/C/D. A two-seat ride based on going up Second Avenue to 125th Street and thence connecting to the 2/3, A/B/C/D, or 1 would enable more connections, many without any backtracking. This could have a potential cascading effect on all Uptown east-west buses, and not just those using 125th Street.

Of course, a Second Avenue Subway extension on 125th Street cannot be exactly like the pink line in the diagram above, because a key feature of it is that the circumferential part is not in fact near the outer end of the city. It’s barely 5 km north of the northern edge of Midtown, not even halfway from Midtown to the northern ends of most preexisting north-south subway lines. This is how it can have such high residential and commercial density and strong transit demand. Much farther north, Fordham Road is a very strong bus corridor, with about 4,500 weekday riders per route-km on the Bx12, but this is at much higher speed than in Manhattan, about 13 km/h rather than 5 km/h. An extension of the A east toward the Bronx under Fordham would underperform, because Fordham just doesn’t have that much demand; but 125th does.

The result of this discrepancy is that in a small city, one whose subway system is only about as large as in the diagram, it’s unlikely that such circumferential extensions would work. A radial line built all the way out is going to have as its terminus either a relatively low-density area or an anchor point, such as a commercial center or big housing project, neither of which lends itself to a strong continuous circumferential corridor. A radial line built part of the way to the edge of the city could potentially find a Tehran Avenue or a 125th Street, but if the system is small, with many key outlying neighborhoods still unserved, then it is usually best to keep extending lines outward.

The factors that conspire to make a 125th Street subway extension work are in place precisely because New York already has a large, mature subway network, in which Second Avenue Subway is a relief line. Certainly the projected demand on Second Avenue is very high, but the East Side is already served by a north-south subway 500-600 meters to the west of this line; it’s being built because this subway is overcrowded, not because the East Side has no access. This means that there’s more leeway with choosing what to do with the line once it reaches Harlem – after all, the Bronx subways are not overcrowded, and do not need relief.

Whereas mixed lines like the above-depicted yellow line are always bad transit, mixed lines like the pink line, in which the circumferential part is farther out than the radial part, are potentially an option for large cities that already have many rapid transit lines. They are especially useful for providing connections between closely parallel radial lines when other crosstown transit options are slow, and should be considered as extensions for relief lines, provided the radial lines farther out do not need relief as well.

Northeast Corridor, 95% Cheaper: Frankford Junction

Amtrak’s plan for high-speed rail on the Northeast Corridor, at a cost of about $290 billion depending on the exact alternative chosen, is unacceptably costly. I went into some details of where excess cost comes from in an older post. In this post, I hope to start a series in which I focus on a specific part of the Northeast Corridor and propose a cheaper alternative than what the NEC Future plan assumes is necessary. The title is taken from a post of mine from four years ago; since then, the projected costs have doubled, hence the title is changed from 90% cheaper to 95% cheaper. In this post, I am going to focus on untangling Frankford Junction.

Frankford Junction is one of the slowest parts of the Northeast Corridor today south of New York. It has a sharp S-curve, imposing a speed limit of 50 mph, or 80 km/h. While worse slowdowns exist, they are all very close to station throats. For example, Zoo Junction just north of Philadelphia 30th Street Station has a curve with radius about 400 meters and an interlocking, so that superelevation is low. The speed limit is low (30 mph, or 50 km/h), but it’s only about 2 km out of the station; it costs about 2 minutes, and with proper superelevation and tilting the speed limit could be doubled, reducing the time cost to 25 seconds. In contrast, Frankford Junction is about 13 km out of 30th Street Station; an 80 km/h restriction there, in the middle of what could be a 200 km/h zone, makes it uneconomic for trains to accelerate to high speed before they clear the junction. This impacts about 4 km, making it a 108-second slowdown, which can be mitigated by either more tilting or a wider curve. In reality, a mixture is required.

The NEC Future plan for high-speed rail, the $290 billion Alternative 3, avoids the Frankford Junction S-curve entirely by tunneling under Center City and building a new HSR station near Market East, a more central location than 30th Street; see PDF-pp. 19, 20, and 78 of Appendix A of the environmental impact statement. This option should be instantly disposed of: 30th Street is close enough to the Philadelphia CBD, and well-connected enough to the region by public transit, that it is no worse a station choice than Shin-Osaka. The Tokaido Shinkansen could not serve Osaka Station as a through-station without tunneling; since Japan National Railways wanted to be able to extend HSR onward, as it eventually did with the Sanyo Shinkansen, it chose to serve Osaka via a new station, Shin-Osaka, 3 km away from the main station. Given the expense of long tunnels under Philadelphia, the slightly less optimal station today should be retained as good enough.

A lower-powered plan providing some HSR functionality, Alternative 2, does not include a new tunnel under Philadelphia, but instead bypasses Frankford Junction. On Appendix A, this is on PDF-pp. 19, 20, and 70. Unfortunately, the bypass is in a tunnel, which appears to be about 4 kilometers. The tunnel has to cross under a minor stream, Frankford Creek, adding to the cost. Instead, I am going to propose an alignment that bypasses the tunnel, with moderate takings, entirely above ground.

In brief, to minimize trip times without excessive construction, it is best to use the highest superelevation and cant deficiency that HSR technology supports today. The maximum superelevation is 200 mm, on the Tokaido Shinkansen (link, PDF-p. 41); there were plans to raise superelevation to 200 mm on the Tohoku Shinkansen, to permit a maximum speed of 360 km/h, but they were shelved as that speed created problems unrelated to superelevation, including noise, pantograph wear, and long braking distances. The maximum cant deficiency on existing trainsets capable of more than 300 km/h is about 180 mm, including the E5/E6 Shinkansen and the Talgo 350 and Talgo AVRIL. Tilting trains capable of nearly 300 mm cant deficiency exist, but are limited to 250 km/h so far. With 200 mm superelevation and 175 mm cant deficiency, speed in meters per second equals square root of (2.5 * curve radius in meters); the minimum curve radius for 200 km/h is then 1,235 meters.

An S-curve requires some distance to reverse the curve, to avoid shocking the train and the passengers with a large jerk, in which they suddenly change from being flung to the right to being flung to the left. If you have ridden a subway, sitting while the train was decelerating, you must have noticed that as the train decelerated, you felt some force pushing you forward, but once the train came to a complete stop, you’d be pulled backward. This is the jerk: your muscles adjusted to being pushed forward and resisting by pulling backward, and once the train stopped, they’d pull you back while adjusting back to the lack of motion. This is why S-curves built a long time ago, before this was well-understood, impose low speed limits.

With today’s computer-assisted design and engineering, it’s possible to design perfect S-curves with constant, low jerk. The limits are described in the above link on PDF-pp. 30 and 38. With the above-described specs, both sets of standards described in the link require 160 meters of ramp. For a single transition from tangent track to a fully superelevated curve, this can be modeled very accurately as 80 meters of straight track plus the circular curve (half the transition spiral is within the curve); the displacement from an actual spiral curve is small. For an S-curve, this requires double the usual transition, so 160 meters of tangent track between the two circles; bear in mind that this distance grows linearly with speed, so on full-speed 360 km/h track, nearly 300 meters are required.

Here is a drawing of two circles and a tangent track between them. The curve of course consists only of a short arc of each circle. The straight segment is a little less than 700 meters, which permits a gentle spiral. The curves have radius 1,250 meters. Takings include a charter school, a wholesale retailer, an auto shop, and what appears to be industrial parking lots, but as far as I can tell no residences (and if I’m wrong, then very few residences, all very close to industrial sites). The charter school, First Philadelphia Preparatory, is expanding, from 900 students in 2012-3 to an expected 1,800 in 2018-9. School construction costs in Pennsylvania are high, and $100 million is expected for a school of that size; see also table 5 on PDF-p. 7 here for national figures. The remaining takings are likely to cost a fraction of this one. Even with the high cost of takings, it is better to realign about 2 kilometers of track above-ground, at perhaps $150 million, than to build 4 km of tunnel, at $1.5 billion; both figures are based on cost items within the NEC Future . This represents a saving of about 83% over Alternative 2, which is projected to cost $116-121 billion excluding rolling stock (PDF-p. 42 of chapter 9 of the EIS).

Given the long spiral length, it may be feasible to avoid the charter school entirely. This would probably require shrinking curve radius slightly, permitting 180 or 190 km/h rather than 200 km/h. However, the travel time cost is measured in seconds: with about 11 km from the end of Zoo Junction to the northern end of Frankford Junction, of which 1 is required just to accelerate to speed, the difference between 200 and 180 km/h is 20 seconds. Further savings, reducing this time difference, are possible if the speed limit without taking the school is 190, or if trains accelerate to 200, decelerate to curve speed, and accelerate again to the north. This option would improve the cost saving over Alternative 2 to about 90%.

The correct way forward for affordable improvement of the Northeast Corridor is to look for ways in which expensive infrastructure can be avoided. If a tunnel can be replaced by a viaduct at the cost of a few extra takings, it should be. If an expensive undertaking can be avoided at the cost of perhaps 10 seconds of extra travel time, then it probably should be avoided. There should be some idea of how much it’s acceptable to spend per minute of marginal travel time saving, by segment: the New York-Philadelphia segment has the heaviest traffic and thus should have the highest maximum cost per unit of time saved. But even then, $100 million for 20 seconds is probably too high, and $100 million for 10 seconds is certainly too high.

What are the Strong Tramway Corridors?

Note on definitions: for the purposes of this post, a tramway is a light rail line that runs predominantly on streets, interfacing with cross-traffic even if it has signal priority. It can be a legacy streetcar in mixed traffic, or a newer light rail line running on dedicated lanes. It is distinguished from lines that have substantial grade-separated segments, including subway-surface lines, where these segments are in city center while the suburban segments are in tramway mode, and tram-trains and most North American light rail lines, where these segments are in the suburbs while the city-center segments are in tramway mode.

Intermediate in capacity between the surface bus and the rapid transit train is the tram. Running on the street, perhaps with signal priority but without the absolute priority that mainline trains have at grade crossings, trams are still surface transit, but feature better ride quality, generally higher capacity in terms of vehicles per hour, and generally bigger vehicles. A number of cities have been building such transit in recent years, most notably Paris, which has been making the rounds on the Transit Center for having almost a million daily riders on its system. The Transit Center gives various recommendations based on Paris’s success, but those recommendations – frequency, fare integration, good transfers – say very little about where a city should be building tramway lines. In this post, I am going to sketch features of good corridors for tramways.

1. Tramways are surface transit

There are various features that make for good surface transit routes. Jarrett Walker, who has extensive experience in bus network redesigns, outlined some of them in a network design document he collaborated on for TransLink. These include high density along the route, relatively balanced demand in both directions, and the potential for a strong everywhere-to-everywhere grid. Additional important features of strong bus routes: a single street with few twists, since turns slow down surface vehicles a lot, and swerving to reach major destinations is often cumbersome; and a wide street, since in practice few cities will give transit dedicated lanes if there’s not enough room for cars as well. These rules do not apply to subways, which can zigzag between different streets or carve a new alignment. However, they do apply to tramways.

2. The strongest bus corridors are in most need of investment

In a city where the buses that can support high frequency already are frequent, the highest potential for extra ridership is on routes that are already strong. Imagine a bus that averages 15 km/h: replacing it with a 20 km/h tram that provides a smoother and more reliable ride has benefits in rough proportion to existing bus ridership. Since both buses and trams are surface transit and follow the same rules, it’s unlikely that there are routes that would make good trams but poor buses. This is in stark contrast with subways, where a potentially strong corridor may not have a continuous surface right-of-way for high bus ridership. On the surface, this corridor could not succeed as either a bus or a tram. This is a specification of the BMT’s all four concept (bus, trolleybus, tramway, subway), in which the four modes work in complement, and the busiest routes in each category are upgraded to the next based on a tradeoff between construction costs and operating costs.

3. In a city with subways, the tramways should be placed on routes that would make poor subway corridors

It goes without saying that tramways should not duplicate subways. But more than that, if a bus route is so strong that it’s a potential subway extension, it should not be turned into a tram. At first pass, this may look like the best bus routes to be turned into trams are not quite the busiest, but the next tier of busier buses. However, this has to do not just with ridership, but also layout relative to the subway system. The subway is almost invariably radial, so strong buses that make easy radials or branches of radials would be strong subway routes, while circumferential buses would not. A radial bus may also turn out to be a poor subway route, if it happens to point in a direction where a subway wouldn’t be a good fit, but this is less likely.

4. A connected network is beneficial, but not required

Ideally, all light rail routes – not just tramways, but also subway-surface routes and tram-trains if they exist – should form a connected graph, with track connections, to enable maximum flexibility in yard placement and reduce the required spare ratio. However, this is not a requirement. Large, busy systems in particular may economically have a yard serving just 1-2 lines, in which case the value of connectedness decreases. In conjunction with point #3, cities with large radial subway networks may have disconnected circumferential tramways, including Paris.

5. When there’s a choice between several tramways and a subway, tramways work better when there’s no dominant route

The construction cost of a subway, in developed countries that are not the US, is $100-300 million per km, with outliers outside the range in both directions. The construction cost of a tramway in the same countries is $15-50 million per km, again, with outliers. The choice of whether to build one subway or six tramways depends on how busy the strongest route is relative to the next five routes. If two strong bus routes are closely parallel, then both should be reckoned together for subway ridership estimates (and to some extent also for tram ridership), since people walk longer to better service, in this case a fast subway rather than a slow bus. Another consideration, more about construction costs than ridership, is whether there exists a good right-of-way for the subway, perhaps an abandoned or low-ridership commuter line that can be converted, that would make it possible to limit tunneling.

Examples

Boston has few long, wide roads; Massachusetts Avenue is one of very few exceptions. Downtown Boston and the surrounding neighborhoods have very narrow streets, which is why the Boston bus network is sparse downtown – the buses feed outlying subway stations, or stop at the edge of the central business district at Haymarket, and almost never enter the downtown core. Because of the Green Line, some strong radial routes, such as the Washington Street half of the Silver Line, and the 23 bus on Blue Hill Avenue, are naturally good extensions of the subway-surface network; they’d make good light rail, but not all-surface tramways.

In strongly gridded cities, including Chicago, Vancouver, Toronto, and Los Angeles, it doesn’t make too much sense to build individual tramways; instead, the entire frequent bus grid could be so upgraded, or possibly just the lines that are perpendicular to the rapid transit system in Chicago and Toronto. Unfortunately, this runs into high construction costs, which leads to questions of priorities: build an expansive light rail network, or extend a few subway lines.

I believe Los Angeles and Vancouver are doing right in choosing to prioritize subways on their strongest corridors. Vancouver in particular is an extreme example of point #5 pointing toward a subway, with 80,000 weekday riders on Broadway and another 40,000 on the routes interlining on 4th Avenue 500 meters away (not all on 4th, as two of the four 4th Avenue routes have substantial tails elsewhere), compared with 110,000 on the next five routes combined; Vancouver also seems to have an unusually low subway-to-tram cost ratio, only about 2.7 rather than 6. Los Angeles has a less extreme version of point #5, but Wilshire and very close-by routes dominate east-west traffic, and can also easily feed into the existing subway.

In Chicago, the circumferential nature of the top bus routes – north-south west of the Loop, east-west north and south of it – makes an L extension infeasible, so from point #3, any solution has to involve surface transit. The current plan is dedicated bus lanes. In Toronto this decision is more difficult, and acrid debates between a mostly-surface option and an all-underground option led to the latter choice, influenced by Rob Ford’s unwillingness to take road lanes from cars; right now Toronto is building one subway line (update: it’s mixed subway-surface), under Eglinton, and one tramway, on Finch West.

New York

In New York, Bill de Blasio proposed a tram route near the Brooklyn and Queens waterfront earlier this year; see background articles here and here. This route is ill-suited for the technology proposed, or for any significant investment. The buses along the waterfront are all quite weak. In both Brooklyn and Queens, the busiest buses are in the interior, some going perpendicular to the subway, such as the Q44 on Main Street and B35 on Church, and some serving radial routes that have long been planned to be subway extensions, namely the B46 on Utica and B44 on Nostrand. Select Bus Service investments have targeted these routes, and now the Q44, B44, and most recently the B46 all have SBS features.

Another weakness of the proposed route is that it subtly combines circumferential and radial service; see here for why this is poor practice. While the line is for the most part straight, the north-south segment in Queens is essentially radial, going from Astoria to Long Island City, parallel to the N/Q subways, before switching to circumferential between Long Island City and Downtown Brooklyn. South of Downtown Brooklyn it becomes radial again, connecting to Red Hook and Sunset Park. Riders in Astoria going south are mostly interested in continuing toward Manhattan and not toward Brooklyn; riders in Sunset Park and Red Hook going north would first of all follow different routes (Sunset Park already has the N and R subways and has no use for a detour through Red Hook), and second of all be more interested in going to Manhattan than to Williamsburg and points north.

While de Blasio’s proposal is bad transit, there are routes in New York that could make strong tramways. None of them is on the city’s redevelopment agenda, based on the principle that US cities almost never invest in low- and lower-middle-income neighborhoods except when they are about to gentrify, but the bus ridership there is solid, even though the buses crawl.

The busiest routes in New York are the M15 on 1st and 2nd Avenues in Manhattan, the B46, and the Bx12 on Fordham Road; each has been the single busiest in one of the last few years, but usually the M15 is first. The first two are strong subway routes: the first phase of Second Avenue Subway will soon open, and the rest will be built when the city can find multiple billions per kilometer for them; Utica is also a strong route, and de Blasio proposed it last year before abandoning the idea. But Fordham satisfies point #4 perfectly: it is circumferential, and can only realistically extend the A train, already the system’s longest route, with a mismatch in potential ridership between the core radial segment and what a Fordham subway would get. The Bx12 was the first route to be turned into SBS, and is either the strongest potential tramway in the city, or one of the few strongest.

Going further down the list, we should eliminate the strong Brooklyn routes, except the B41 on Flatbush. The B44 is also a potential subway extension, and the three busiest circumferentials – the B6, B35, and B82 – all parallel the Triboro right-of-way, which by point #5 is a superior project to building multiple light rail lines. The busiest bus in Queens, the Q58, has a long segment between Queens and Brooklyn, about half its total length, that would be obviated by Triboro as well.

The B41 could be a tramway going between City Hall and Kings Plaza, using two dedicated lanes of the Brooklyn Bridge. In that case, the line would effectively act as subway-surface, or more accurately elevated-surface: a surface segment in Brooklyn, a grade-separated segment between Manhattan and Brooklyn. Subway-surface lines should branch, as all current examples do (e.g. Boston Green Line, Muni Metro, Frankfurt U-Bahn), because the subway component has much higher capacity than the surface components. This suggests one or two additional routes in Brooklyn, which do not have strong buses, but may turn into strong tramways because of the fast connection across the river to Manhattan. The first is toward Red Hook, which is not served by the subway and cut off from the rest of the city by the Gowanus Expressway. Unfortunately, there is no really strong corridor for it – the streets are not very wide, and the best for intermediate ridership in Cobble Hill and Carroll Gardens require additional twists to get into the core of Red Hook. Court Street might be the best compromise, but is annoyingly a block away from the F/G trains, almost but not quite meeting for a transfer. The second possible route is along Flushing Avenue toward the Navy Yard; it’s not a strong bus by itself, but the possibility of direct service to Manhattan, if a Flatbush tramway preexists, may justify it.

In the Bronx and Queens, a more conventional network is called for. The Bronx in particular has several strong bus lines forming a good grid, in addition to the Bx12. The east-west routes cannot possibly be made into subway extensions, while the north-south ones have nowhere to go to in Manhattan except possibly a Second Avenue Subway extension, and even that is doubtful (if there’s money to extend Second Avenue Subway north, it should instead go west under 125th Street). A light rail grid could consist of the Bx12 as outlined above, a Tremont line acting as a compromise between the Bx36 and Bx40/42 feeding into Manhattan on 181st Street, a 161st/163rd Street route going into Manhattan on 155th Street replacing the Bx6, a Southern/Manhattan 145th Street route along the Bx19, a Third Avenue route along the Bx15, and a Grand Concourse route along the Bx1/2. Grand Concourse has a subway, but the Bx1/2 nonetheless currently ranks 5th in the city in weekday ridership, and the street is so wide that it’s a good candidate for light rail. Update: a Webster Avenue route along the Bx41 is also feasible, I just forgot it when writing this post.

In Queens, there’s less room for a grid. Main Street is a strong route, connecting to Tremont in the Bronx via the Whitestone Bridge, as the Q44 SBS already does today. A second route between Flushing and Jamaica, on Kissena and Parsons, could also get a tramway. These two routes are uniquely bad subways, since they connect two busy subway lines, both of which could be extended past their termini outward. The main route on Kissena, the Q25, and another route slightly farther east, the Q65, rank 3rd and 2nd among the MTA buses, separate from the New York City Transit buses, with about 20,000 weekday riders each; they also continue north to College Point, which could get a tramway, or perhaps even a subway extension of the 7, depending on whether there are plans to redevelop the Flushing Airport site.

If there is not enough ridership on both Kissena and Main, then only Main should be turned into light rail. More potential corridors include the Q46 on Union Turnpike and the Q10 on Lefferts going to JFK (the busiest MTA bus). Unfortunately, Queens buses tend to be on the long side, e.g. the Q27, the borough’s number 3 bus after the Q58 and Q46, is 15 km long; in the Bronx the longest, Tremont, would be 13 km, cobbled out of busier buses, and most are about 10 km. The Q44 is even longer, at 20 km; light rail is only justified there because of extra local ridership coming from the Q20 local and from the fact that the Queens-Bronx segment over the bridge would be rapid transit. Even then, the tramway may only be justified from Flushing south.

I don’t want to make recommendations for priorities and an exact fantasy map in New York, as those depend on construction costs and the available budget. Fordham and Main Street are most likely the two strongest initial choices. Judging by the cost estimate for de Blasio’s waterfront proposal, tramways in New York are about $60-70 million per km, which in an inverse of the situation in Vancouver leads to an unusually high subway : tram cost ratio, 25 if we take the Manhattan subway extensions (Second Avenue and the 7 extension) as our examples, probably less but not much less if we look at a hypothetical Utica subway. This should bias New York rail extensions toward surface transit.

De Blasio proposed $1.5 billion for about 25 km of tramway on the waterfront. The waterfront idea is bad, and money can and should go elsewhere; 25 km is slightly longer than the combined length of the Bx12 and the B46 from Flushing south. Those two together could be the start of a program to bring surface rail back to New York, using the same routing reasoning that made Paris’s program so successful. Using ridership on the existing buses and adjusting upward for rail bias, initial ridership on those two lines combined should be higher than 100,000 per day, and with more lines and a bigger network, fast multiplication of overall traffic can be expected.

Public Transit Unions

In this post, I would like to explain an observation: public transit workers are unionized even in countries where few workers belong to a union, such as the US and the UK. Attempts by management to win concessions from the unions have often led to prolonged strikes, for example the 108-day strike by SEPTA workers in 1983. This is not just the public sector: the private railroads in the US are unionized, and in 1964 the Florida East Coast Railway had a year-long strike. Nor is this because the public operators and private railroads have a unionized legacy: many private bus shuttles used by Bay Area tech firms to get workers from San Francisco to Silicon Valley offices have unionized drivers, including Facebook and Google, even though the tech industry as a whole is predominantly non-union. Public transportation workers, especially on-board crew, are in a position of strength, and I would like to explain why.

First, let us recount how unions work. At their heart is collective bargaining: the union negotiates wages and benefits for the entire membership. An individual worker who is paid too little can quit, which is unlikely to cause the employer much concern; a union can launch a strike, thereby getting higher wages and better work conditions than each individual worker could obtain alone.

In order to be able to collectively bargain, there needs to be a collective in the first place, which means two separate things:

  1. Politically, there needs to be a sense of solidarity among the workers. The workers need to see each other as comrades, or as colleagues, and not as competitors. They need to feel like the union represents their interest. This is unlikely to happen in industries where there is substantial competition for promotions to managerial roles, but easier in industries with clear separation between line workers and managers. It is also unlikely to happen in industries with rapid turnover of employees.
  2. Economically, there needs to be a reasonable way to set a uniform wage scale. This means that the work done by the various employees in each category must be interchangeable, or close enough to it that wages can be made equal. In turn, this requires that the job not have a strong sense of merit, in which some workers are persistently much more productive than others. Productivity differences should be related to seniority, or easily worked into wage agreements (for examples, sales agents can collectively bargain for a uniform commission structure). It’s fine if there is differentiation into several job categories, but then it’s best if this differentiation is rigid, so that workers in each group do not often have to do the job of workers in other groups.

Conversely, if the union goes on strike, management has tools to fight back, including the lockout, or more commonly hiring strikebreakers. To deter management from doing so, the union can exercise peer pressure on people not to scab (condition 1 above), but it also union needs to also fulfill a third condition:

  1. The job must be skilled enough that it is hard for the employer to hire and train strikebreakers quickly. On a nationwide basis this makes unionization easier in a tight labor market, hence socialist support for monetary policy that prioritizes full employment over price stability. But on a per-industry basis, this condition requires some difficult pipeline that workers must go through: a degree, long training, apprenticeship, or bespoke familiarity with the project at hand.

Conditions 2 and 3 are in tension, since skilled jobs are more likely to involve workers with different levels of productivity. For example, retail workers fulfill condition 2, but are easy to replace if they go on strike and the labor market is not tight. In contrast, programmers easily fulfill condition 3, in the sense that if the entire development team on a project quits, it will be difficult for the company to find a new one and get it up to speed, but because there is a wide range of productivity levels, it makes little sense for programmers to all be paid the same. Silicon Valley’s business culture, in which developing a product fast is more important than establishing a business culture, and turnover is encouraged, also makes it hard to establish meaningful solidarity among software developers.

In the intersection between these three conditions lie a set of job descriptions in which there is a strong sense of professionalism, to meet condition 3, but a weak sense of merit, to meet condition 2. These jobs are typically static in the sense of not changing too much over the years, which makes it ideal for a person to do the same thing for their entire life, learning to adopt new technologies gradually as they are introduced but not having to change their entire skillset. Often, the industries these jobs are in are static as well, whence they are more easily done by the public sector, or by large conglomerates that have been around for generations, such as the private US railroads.

Commercial drivers – of buses, trucks, trains, planes – are a major example of people who satisfy all three conditions. One racecar driver can be better than the next by being faster, but in the commercial sector, speeds are determined by the equipment, the schedule, and the safety standards. A train driver can be better than another on the margins, by responding more quickly to an obstacle on the tracks, or paying attention to the posted schedule better, but both of these aspects depend more on external factors, such as the signal system, than on driver skill. Train schedule padding, accounting for suboptimal driver behavior such as beginning to brake too early but also for propagating delays and passengers who take too long to board or alight, consists of a few percent of total travel time: in its peer review of California High-Speed Rail, JR East proposes 3-5% (PDF-p. 10); and a Swedish study for high-speed rail mentions a 0.9-2.3% discrepancy in energy consumption based on driver behavior (PDF-p. 12) and a total schedule pad equal to about 7% of travel time (PDF-p. 24). The productivity difference, or in other words individual merit, is too small to challenge the logic of a uniform wage scale.

Instead of individual merit, commercial drivers have professionalism. A train driver is expected to fulfill certain criteria to ensure safety first and punctuality second, which requires considerable study of the route of the train, the signal systems, the dispatching codes, the correct way to respond to various unforeseen circumstances. Unlike individual car drivers, commercial drivers are not permitted to take small risks in other to go faster, and learning how to pilot a vehicle safely takes some time; all of this is true manifold if the vehicle in question is a plane, leading to arduous certification requirements. In this setting, even in an environment of absolute control by management, there’s little reason to have different payscales – at most, management can penalize workers who make mistakes.

For the same reasons that train drivers have standards of professionalism, it is easy for them to form a cultural group with internal solidarity. They have their own knowledge set and jargon, as anyone who has tried reading threads on railfan forums knows. The transportation industry changes slowly enough, in terms of both travel demand and technological progress, that most train drivers can expect to work for the same company for decades. Even bus drivers, in an industry that’s less dependent on physical plant, can expect to move between bus operators.

The other major category of public transportation workers, maintenance workers, is not as clear-cut. There is certainly a difference in merit – some people just fix things faster than others. But at the same time, the importance of safety is such that giving financial incentive to working faster can lead to shoddy work. Instead, there are extensive regulations, developed by national safety authorities as well as internally by rail operators, specifying which tasks need to be performed and at what intervals.

Unlike train drivers, maintenance workers aren’t interchangeable – they have more specific job titles. But these job titles often lend themselves to easy categorization, such as electricians and welders. Those have their own standards, and the potential for major accidents encourages uniformity of credentials and of wages, while the complexity of the machinery these workers operate ensures that they must be skilled. This leads to the same presence of professionalism without differential individual merit seen in the case of train drivers, and ensures all three conditions facilitating unionization are present.

In a healthy company, technology progresses as fast as it can given the requirements of the industry, and the union rules are reasonable. Wages and benefits are higher with collective bargaining than without almost by definition, but they cannot be massively higher – those are skilled workers, who are not easily replaceable. In environments where the rules are unreasonable – perhaps the certification requirements are more onerous than necessary, perhaps labor-saving technologies are not used, perhaps the work rules are not suitable for a modern operation – management cannot easily force the union’s hand. Even when three people do the job of one, as in the case of US commuter rail operations with conductors and assistant conductors, labor is in a position of power, and reform-minded managers cannot easily hire strikebreakers.

Greenbelts Help Cars

A number of major cities, most notably London, have designated areas around their built-up areas as green belts, in which development is restricted, in an attempt to curb urban sprawl. The towns within the green belt are not permitted to grow as much as they would in an unrestricted setting, where the built-up areas would merge into a large contiguous urban area. Seeking access to jobs in the urban core, many commuters instead live beyond the greenbelt and commute over long distances. There has been some this policy’s effect on housing prices, for example in Ottawa and in London by YIMBY. In the US, this policy is less common than in Britain and Canada, but exists in Oregon in the form of the urban growth boundaries (UGBs), especially around Portland. The effect has been the same, replacing a continuous sprawling of the urban area with discontinuous suburbanization into many towns; the discontinuous form is also common in Israel and the Netherlands. In this post, I would like to explain how, independently of issues regarding sprawl, such policies are friendlier to drivers than to rail users.

Let us start by considering what affects the average speed of cars and what affects that of public transit. On a well-maintained freeway without traffic, a car can easily maintain 130 km/h, and good cars can do 160 or more on some stretches. In urban areas, these speeds are rarely achievable during the day; even moderate traffic makes it hard to go much beyond 110 or 120. Peak-direction commutes are invariably slower. Moreover, when the car gets off the freeway and onto at-grade arterial roads, the speed drops further, to perhaps 50 or less, depending on density and congestion.

Trains are less affected by congestion. On a well-maintained, straight line, a regional train can go at 160 km/h, or even 200 km/h for some rolling stock, even if headways are short. The busiest lines are typically much slower, but for different reasons: high regional and local traffic usually comes from high population density, which encourages short stop spacing, such that there may not be much opportunity for the train to go quickly. If the route is curvy, then high density also makes it more difficult to straighten the line by acquiring land on the inside of the curves. But by and large, slowdowns on trains come from the need to make station stops, rather than from additional traffic.

Let us now look at greenbelts of two kinds. In the first kind, there is legacy development within the greenbelt, as is common around London. See this example:

greenbelt1

 

The greenbelt is naturally in green, the cities are the light blue circles with the large central one representing the big city, and the major transportation arteries (rail + freeway) are in black. The towns within the greenbelt are all small, because they formed along rail stops before mass motorization; the freeways were built along the preexisting transportation corridors. With mass motorization and suburbanization, more development formed right outside the greenbelt, this time consisting of towns of a variety of sizes, typically clustering near the freeways and railways for best access to the center.

The freeways in this example metro area are unlikely to be very congested. Their congestion comes from commuters into the city, and those are clustered outside the greenbelt, where development is less restricted. Freeways are widened based on the need to maintain a certain level of congestion, and in this case, this means relatively unimpeded traffic from the outside of the green belt right up until the road enters the big city. Under free development, there would be more suburbs closer to the city, and the freeway would be more congested there; travel times from outside the greenbelt would be longer, but more people would live closer to the center, so it would be a wash.

In contrast, the trains are still going to be slowed down by the intermediate stops. The small grandfathered suburbs have no chance of generating the rail traffic of larger suburbs or of in-city stops, but they still typically generate enough that shutting them down to speed traffic is unjustified, to say nothing of politically impossible. (House prices in the greenbelt are likely to be very high because of the tight restrictions, so the commuters there are rich people with clout.) What’s more, frequency is unlikely to be high, since demand from within the greenbelt is so weak. Under free development, there might still be more stops, but not very many – the additional traffic generated by more development in those suburbs would just lead to more ridership per stop, supporting higher frequency and thus making the service better rather than worse.

Let us now look at another greenbelt, without grandfathered suburbs, which is more common in Canada. This is the same map as before, with the in-greenbelt suburbs removed:

greenbelt2

In theory, this suburban paradigm lets both trains and cars cruise through the unbuilt area. Overall commutes are longer because of the considerable extra distance traveled, but this distance is traversed at high speed by any mode; 120 km/h is eminently achievable.

In practice, why would there be a modern commuter line on any of these arteries? Commuter rail modernization is historically a piecemeal program, proceeding line by line, prioritizing the highest-trafficked corridors. In Paris, the first commuter line to be turned over to the Metro for operation compatible with city transit, the Ligne de Sceaux, has continuous urban development for nearly its entire length; a lightly-trafficked outer edge was abandoned shortly after the rest of the line was electrified in 1938. If the greenbelt was set up before there was significant suburbanization in the restricted area, it is unlikely that there would have been any reason to invest in a regional rail line; at most there may be a strong intercity line, but then retrofitting it to include slower regional traffic is expensive. Nor is there any case for extending a high-performing urban transit line to or beyond a greenbelt. Parts of Grand Paris Express, namely Lines 14 and 11, are extended from city center outward. In contrast, in London, where the greenbelt reduces density in the suburbs, high investment into regional rail focuses on constructing city-center tunnels in Crossrail and Crossrail 2 and connecting legacy lines to them. In cities that do not even have the amount of suburban development of the counties surrounding London, there is even less justification for constructing new transit.

Now, you may ask, if there’s no demand for new urban transit lines, why is there demand for new highways? After all, if there was not much regional travel into these suburbs historically, why would there be enough car traffic to justify high investment into roads? The answer is that at low levels of traffic, it’s much cheaper to build a road than to build and operate a railway. This example city has no traffic generators in the greenbelt, except perhaps parks, so roads are cheap to build and have few to no grade crossings to begin with, making it easier to turn them into full freeways. The now-dead blog Keep Houston Houston made this point regarding a freeway in Portland, which was originally built as an arterial road in a narrow valley and had few at-grade intersections to be removed. At high levels of demand, the ability to move the same number of people on two tracks as on fourteen lanes of freeway makes transit much more efficient, but at low demand levels, rail still needs two tracks or at least one with passing sidings, and high-speed roads need four lanes and in some cases only two.

The overall picture in which transit has an advantage over cars at high levels of density is why high levels of low-density sprawl are correlated with low transit usage. But I stress that even independently of sprawl, greenbelts are good for cars and bad for transit. A greenbelt with legacy railway suburbs is going to feature trains going at the normal speed of a major metro area, and cars going at the speed of a more spread out and less populated region. Even a greenbelt without development is good urban geography for cars and bad one for transit.

As a single exception, consider what happens when a greenbelt is reserved between two major nodes. In that specific case, an intercity line can more easily be repurposed for commuting purposes. The Providence Line is a good example: while there’s no formal greenbelt, tight zoning restrictions in New England even in the suburbs lead to very low density between Boston and Providence, which is nonetheless served by good infrastructure thanks to the strength of intercity rail travel. The MBTA does not make good use of this infrastructure, but that’s beside the point: there’s already a high-speed electrified commuter line between the two cities, with widely spaced intermediate stops allowing for high average speeds even on stopping trains and overtakes that are not too onerous; see posts of mine here and here. What’s more, intercity trains can be and are used for commutes from Providence to Boston. For an analogous example with a true greenbelt, Milton Keynes plays a role similar to Providence to London’s Boston.

However, this exception is uncommon. There aren’t enough Milton Keyneses on the main intercity lines to London, or Providences on the MBTA, to make it possible for enough transit users to suburbanize. In cities with contiguous urban development, such as Paris, it’s easier. The result of a greenbelt is that people who do not live in the constrained urban core are compelled to drive and have poor public transportation options. Once they drive, they have an incentive to use the car for more trips, creating more sprawl. This way, the greenbelt, a policy that is intended to curb sprawl and protect the environment, produces the exact opposite results: more driving, more long-distance commuting, a larger urban footprint far from the core.

A Theory of Zoning and Local Decisionmaking

This weekend there’s a conference in the US, YIMBY 2016, by a national network of activists calling for more housing. I am not there, but I see various points raised there via social media. One is a presentation slide that says “NIMBYism is a collective action problem: no single neighborhood can lower prices by upzoning; might still be in everyone’s interest to upzone at city/state level.” I think this analysis is incorrect, and in explaining why, I’d like to talk about a theory of how homeowners use zoning to create a housing shortage to boost their own property values, and more generally how long-time residents of a city use zoning to keep out people who are not like them. In this view,zoning is the combination of a housing cartel, and a barrier to internal migration.

For years, I’ve had trouble with the housing cartel theory, because of a pair of observations. The first is that, contra the presentation at YIMBY, zoning is driven by homeowners rather than by renters; for an overview, see the work of William Fischel. The second is that restrictive zoning typically correlates with local decisionmaking, such as in a neighborhood or small city, while lax zoning typically correlates with higher-level decisionmaking, such as in a city with expansive municipal boundaries or in an entire province or country; see below for more on this correlation. These two observations together clash with the housing cartel theory, for the inverse of the reason in the above quote from the YIMBY presentation: it’s more effective to create a housing shortage in a large area than in a small one.

To a good approximation, land value equals (housing price – housing construction cost)*allowed density. If a small municipality upzones, then as in the quote, housing price doesn’t change much, but allowed density grows, raising the price a homeowner can get by selling their house to developers who’d build an apartment building. In contrast, if a large municipality upzones then housing prices will fall quite a bit as supply grows, and depending on the price elasticity, land value might well go down. If x = housing price/housing construction cost and e = price elasticity for housing, i.e. price is proportional to density^(-1/e), then maximum land value occurs when x = e/(e-1), provided e > 1; if e < 1 then maximum value occurs when x is arbitrarily large. Price elasticity is much higher in a small municipality, since even a large increase in local housing supply has a small effect on regional supply, limiting its ability to reduce prices. This implies that, to maximize homeowner value, small municipalities have an incentive to set density limits at a higher level than large municipalities, which will be seen in faster housing growth relative to population growth.

What we see is the exact opposite. Consider the following cases, none a perfect natural experiment, but all suggestive:

1. In the Bay Area, we can contrast San Francisco (a medium-size urban municipality), San Jose and generally Santa Clara County (San Jose is medium-size for a central city and very large for a suburb), and San Mateo County (comprising small and medium-size suburbs). San Mateo County is by far the stingiest of the three about permitting housing: over the last three years it’s averaged 1,000 new housing units per year (see here); in 2013, the corresponding figures elsewhere in the Bay Area were 2,277 new housing units in San Francisco and 5,245 in Santa Clara County. Per thousand people (not per housing unit), this is 2.63 in San Francisco, 2.73 in Santa Clara, and 1.31 in San Mateo. In Alameda County, comprising medium-size cities and suburbs, with a less hot housing market because of the distance from Silicon Valley jobs, growth was 2,474 units, 1.51 per 1,000 people. In small rich Silicon Valley municipalities like Palo Alto and Menlo Park, NIMBYs have effectively blocked apartment construction; in much larger and still rich San Jose, the city has a more pro-growth outlook.

2. Among the most important global cities – New York, Paris, London, and Tokyo – Tokyo has by far the fastest housing stock growth, nearly 2% a year; see article by Stephen Smith. In Japan, key land use decisions are made by the national government, whereas in Paris, London, and New York, decision is at a lower level. London builds more than New York and Paris; its municipal limit is much looser than Paris’s, with 8.5 million people to Paris’s 2.2 million even though their metro areas have similar populations. New York has a fairly loose limit as well, but the development process empowers lower-level community boards, even though the city has final authority.

3. Canada has a relatively permissive upzoning process, and in Ontario, the planning decisions are made at the provincial level, resulting in about 1.3% annual housing growth in Toronto in the previous decade; in the same period, San Jose’s annual housing growth was about 1% and San Francisco’s was 0.9%.

4. France has recently made a national-level effort to produce more housing in the Paris region, especially social housing, due to very high housing prices there. Last decade, housing production in Ile-de-France was down to about 30,000-35,000 per year, averaging to 2.6 per 1,000 people, similar to San Francisco; see PDF-pp. 4-5 here and the discussion here. With the new national and regional effort at producing more social housing, plans appear to be on track to produce 30,000 annual units of social housing alone in the next few years; see PDF-p. 6 here. With 7,000 annual units within city limits, Paris expects to build somewhat more per capita than the rest of the region.

In France, the combination of a national focus on reducing housing burden and the observation that higher-level decisionmaking produces more housing makes sense. But elsewhere, we need to ask how come homeowners aren’t able to more effectively block construction.

My theory is that the answer involves internal migration. Consider the situation of Palo Alto: with Stanford and many tech jobs, it is prime location, and many people want to move there. The homeowners are choosing the zoning rule that maximizes their ability to extract rents from those people, in both the conventional sense of the word rent and the economic sense. Now consider decisionmaking at the level of the entire state of California. California can raise housing prices even more effectively than Palo Alto can by restricting development, but unlike Palo Alto, California consists not just of residents of rich cities, but also of residents of other cities, who would like to move to Palo Alto. In the poorer parts of the state, there’s not much point in restrictive zoning, because there isn’t that much demand for new housing, except perhaps from people who cannot afford San Francisco or Los Angeles and are willing to endure long commutes. On the contrary, thanks to the strength of internal migration, a large fraction of prospective residents of Palo Alto live elsewhere in California. Nor do people in poor areas, where houses aren’t worth much as investments, gain much from raising house prices for themselves; the ability to move to where the good jobs are is worth more than raising housing prices by a few tens of thousands of dollars. This means that the general interest in California is to make Palo Alto cheaper rather than more expensive. The same is true of Japan and Tokyo, or France and Paris, or Ontario and Toronto.

While superficially similar to the point made in the presentation quoted at the beginning of this post, my theory asserts the opposite. The issue is not that individual municipalities see no benefit in upzoning since it wouldn’t reduce rents by much. It’s that they see net harm from upzoning precisely because it would reduce rents. It is not a collective action problem: it is a problem of disenfranchisement, in which the people who benefit from more development do not live in the neighborhoods where the development would be taking place. High-level decisionmaking means that people who would like to move to a rich area get as much of a vote in its development policy as people who already live there and have access to its amenities, chief of which is access to work. It disempowers the people who already have the privilege of living in these areas, and empowers the people who don’t but would like to.

Individual rich people can be virtuous. Rich communities never are. They are greedy, and write rules that keep others out and ruthlessly eliminate any local effort to give up their political power. They will erect borders and fences, exclude outsiders, and demagogue against revenue sharing, school integration, and upzoning. They will engage in limited charity – propping up their local poor (as San Francisco protects low-income lifelong San Franciscans via rent control), and engaging in symbolic, high-prestige giving, but avoid any challenge to their political power. Upzoning is not a collective action problem; it is a struggle for equal rights and equal access to jobs regardless of which neighborhood, city, or region one grew up in.