I’ve recently started working part-time on a project for the Marron Institute at NYU about bus restructuring in Brooklyn; at the end of this summer, I expect to release a proposal for service upgrades and a new map. I’m working on this with Marron scholar Eric Goldwyn, who is funded by the TWU, which is worried that ridership collapse may lead to service cuts and job losses, but I’m funded directly by Marron and not by the union.
Some of what’s likely to appear in the final report should be familiar to regular readers of this blog, or of Human Transit, or of the work TransitCenter has been doing. As I wrote in Curbed earlier this year, bus operating costs in New York are unusually high because the buses are slow, as the main operating costs of buses scale with service-hours and not service-km. Thus, it’s important to speed up the buses, which allows either providing higher frequency at the same cost or the same frequency at lower cost. A bus speedup should include systemwide off-board fare collection and all-door boarding (common in the German-speaking world but also in San Francisco), wider stop spacing, dedicated lanes wherever there is room, and signal priority at intersections; the TWU is an enthusiastic proponent of off-board fare collection, for reasons of driver safety rather than bus speed.
While bus speedups are critical, their impact is not as Earth-shattering as it might appear on paper. New York’s SBS routes have all of the above features except signal priority, and do save considerable time, but are still slow city buses at the end of the day. Brooklyn has two SBS routes: the B44 on Nostrand, averaging 15 km/h (local B44: 11.3), and the B46 on Utica, averaging 13.7 (local B46 on the shared stretch: 10.8). Their speed premiums over the local routes are toward the high end citywide, but are still 30%, not the 200% speed premium the subway enjoys. Moreover, the speed premium over non-SBS limited routes is 15-20%; put another way, between a third and a half of the speed premium comes purely from skipping some stops.
I mentioned in my last post that I met Carlos Daganzo at Berkeley. Daganzo was responsible for the Barcelona bus redesign, Nova Xarxa; you can read some details on Human Transit and follow links to the papers from there. The guiding principles, based on my conversation with Daganzo and on reading his papers on the subject, are,
- Barcelona has high, relatively uniform density of people and jobs, so there’s no need for buses to hit one CBD. Brooklyn has about the same average residential density as Barcelona, but has a prominent CBD at one corner, but as this CBD is amply served by the subway, it’s fine for buses to form a mesh within the subway’s gaps.
- Nova Xarxa involved widening the stop spacing in Barcelona from less than 200 meters to three stops per km, or a stop every 300-350 meters; Daganzo recommends even wider stop spacing.
- While Barcelona’s street network is strictly gridded, the buses don’t run straight along the grid, but rather detour to serve key destinations such as metro stops. This is an important consideration for Brooklyn, where there are several distinct grids, and where subway stops don’t always serve the same cross street, unlike in Manhattan, where crosstown routes on most two-way streets are assured to intersect every north-south subway line.
- The percentage of transfers skyrocketed after the network was implemented, standing at 26% at the end of 2015, with the model predicting eventual growth to 44%, up from 11% before the redesign.
- The network was simplified to have 28 trunk routes, the least frequent running every 8 minutes off-peak.
The high off-peak frequency in Barcelona is a notable departure from Jarrett Walker’s American network redesigns; the evidence in Houston appears mixed – ridership is about flat, compared with declines elsewhere in the country – but the percentage of transfers does not seem to have risen. Jarrett says in his book that having a bus come every 10 minutes means “almost show-up-and-go frequency” with no need to look at schedules, but his work in Houston and more recently in San Jose involves routes running every 15 minutes.
Moreover, unreliable traffic in these car-dominated cities, in which giving buses dedicated lanes is politically too difficult, means that the buses can’t reliably run on a schedule, so the buses do not run on a clockface schedule, instead aiming to maintain relatively even headways. (In contrast, in Vancouver, a less congested street network, with priority for all traffic on the east-west main streets on the West Side, ensures that the buses on Broadway and 4th Avenue do run on a fixed schedule, and the 4th Avenue buses have a 12-minute takt that I still remember four years after having left the city.)
I’ve talked about the importance of radial networks in my posts about scale-variant transit. I specifically mentioned the problem with the 15-minute standard as too loose; given a choice between an untimed 15-minute network and a timed 30-minute network, the latter may well be more flexible. However, if the buses come every 5 minutes, the situation changes profoundly. Daganzo’s ridership models have no transfer penalty or waiting penalty, since the buses come so frequently. The models the MTA uses in New York have a linear penalty, with passengers perceiving waiting or transferring time on the subway as equivalent to 1.75 times in-motion time; bus waiting is likely to be worse, since bus stops are exposed to the elements, but if the average wait time is 2.5 minutes then even with a hefty penalty it’s secondary to in-vehicle travel time (about 18 minutes on the average unlinked bus trip in New York).
Unfortunately, that high frequently does not exist on even a single bus line in Brooklyn. Here is a table I created from NYCT ridership figures and timetables, listing peak, reverse-peak, and midday frequencies. Five routes have better than 10-minute midday frequency: the B12, the B6 and B35 limited buses, and the B44 and B46 SBSes, running every 7, 7.5, 8, 8, and 6 minutes respectively. In addition, the B41 limited and B103 have a bus every 9 and 7.5 minutes respectively on their trunks, but the B41 branches on its outer end with 18-minute frequencies per branch and the B103 short-turns half the buses. Another 14 routes run every 10 minutes off-peak, counting locals and limiteds separately.
The problem comes from the split into local and limited runs on the busiest buses. The mixture of stopping patterns makes it impossible to have even headways; at the limited stops, the expected headway in the worst case is that of the more frequent of the two routes, often about 10 minutes. The average ridership-weighted speed of Brooklyn buses is 10.75 km/h. An able-bodied passenger walking at 6 km/h with a 10-minute head start over a bus can walk 2.25 km before being overtaken, which can easily grow to 3 km taking into account walking time to and from bus stops. To prevent such situations, it’s important to run buses much more frequently than every 10 minutes, with consistent stopping patterns.
This does not mean that NYCT should stop running limited buses. On the contrary: it should stop running locals. The SBS stop spacing, every 800 meters on the B44 and B46, is too wide, missing some crossing buses such as the B100 (see map). However, the spacing on the B35 limited is every 400 meters, enough to hit crossing buses even when they run on one-way pairs on widely-spaced avenues. The question of how much time is saved by skipping a stop is difficult – not only do different Brooklyn buses give different answers, all lower than in Manhattan, but also the B35 gives different answers in different directions. A time cost of 30 seconds per stop appears like a good placeholder, but is at the higher end for Brooklyn.
The question of how many stops to add to SBS on the B44 and B46 has several potential answers, at the tight end going down to 400 meters between stops. At 400 meters between stops, the B44 would average 13 km/h and the B46 12 km/h. At the wide end, the B44 and B46 would gain stops at major intersections: on the B44 this means Avenue Z, R, J, Beverly, Eastern Parkway, Dean, Halsey, and Myrtle, for an average interstation of 570 meters and an average speed of 14 km/h, and on the B46 this means Avenue U, Fillmore, St. John’s, and Dean, for an average interstation of 610 meters an average speed of 13 km/h. Consolidating all buses into the same stopping pattern permits about a bus every 2.5 minutes peak and every 4 minutes off-peak on both routes.
On the other routes, consolidating local and limited routes required tradeoffs and cannibalizing some peak frequency to serve the off-peak. While it may seem dangerous to limit peak capacity, there are two big banks that can be used to boost off-peak frequency: time savings from faster trips, and greater regularity from consolidating stop patterns. The B82 is an extremely peaky route, running 7 limited and 10 local buses at the peak and just 6 buses (all local) for a four-hour midday period; but there is a prolonged afternoon shoulder starting shortly after noon with another 6 limited buses. Some peak buses have to be more crowded than others just because of schedule irregularity coming from having two distinct stop patterns. Consolidating to about 15 buses per hour peak and 10 off-peak, cannibalizing some frequency from the peak and some from the shoulders, should be about neutral on service-hours without any additional increase in speed.
The sixth post on this blog, in 2011, linked to frequent maps of Brooklyn, Manhattan, and Bronx buses, using a 10-minute standard. There has been some movement in the top buses since 2011 – for one, the B41 route, once in the top 10 citywide, has crashed and is now 16th – but not so much that the old map is obsolete. A good place to start would be to get the top routes from a 10-minute standard to a 6-minute standard or better, using speed increases, rationalization of the edges of the network, and cannibalization of weak or subway-duplicating buses to boost frequency.