Buses in Brooklyn: Frequency is Freedom, but 15 Minutes isn’t Frequency

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.

21 comments

  1. Alon Levy

    Daganzo’s model assumes that buses accelerate at a constant rate a to infinite speed and that stops are instantaneous; see PDF-pp. 33-35 in his textbook. The answer it gives is \sqrt[3]{4v^{2}_{\mbox{walk}}d^{2}_{\mbox{avg}}/a}.

    For davg = 4,000, vwalk = 1, a = 1, we get an optimum of 400 meters.

    My model, based on a constant stop penalty t, gives \sqrt{4tv_{\mbox{walk}}d_{\mbox{avg}}}.

    For t = 30, we get an optimum of 690 meters. This is probably too wide, if only because of the issue I’ve discussed re subways (see here and here), that if stops are too far apart then it’s easy to have lines intersecting without a transfer. Hence the minimal stopping pattern in the post for the B44 and B46, with about a stop every 600 meters.

  2. FDW

    I think that a fair amount of what you’re talking about also applies to San Francisco’s bus service, where you have a fair number of local/limited bus pairs and stop spacing that often reaches below 100m.

  3. alexhutcheson

    Are there any numbers on how longer stop spacing on local buses would impact Access-A-Ride eligibility and usage?

    Access-A-Ride’s [eligibility criteria](http://web.mta.info/nyct/paratran/guide.htm#eligibility) are pretty vague:

    > Distance: Customer is eligible for all trips that require her/him to travel to a bus stop or subway station that is more than the number of blocks she/he has been determined able to travel: 1-2, 3-4, or 5 or more blocks.

    It’s not clear how many Access-A-Ride users would fall into each bucket, or how long the actual distances would be, since block sizes vary.

    At the margins, it seems that longer stop spacings would increase Access-A-Ride utilization, and therefore the cost of that program. This would reduce the savings generated from running faster buses, but it’s not clear what the quantitative trade-offs are.

    • Alon Levy

      The big accessibility issue is bus-subway connections. The subway is mostly inaccessible, and redeploying buses to connect with it might lead to problems there.

      Bear in mind that the 400-meter standard already takes disabilities into account. The models used to optimize bus stop spacing assume a pedestrian walking speed far lower than that of able-bodied people.

      • Michael James

        The models used to optimize bus stop spacing assume a pedestrian walking speed far lower than that of able-bodied people.

        I believe the reason is related to old people who are over-represented amongst bus users. If there is any attempt to move “their” bus stop they become extremely cranky and start writing letters to the local councilman etc. And woebetide if one of them falls and breaks a hip while making a long walk to the closest bus. With the ageing of western populations this can’t get any easier.
        For these reasons I believe bus routes will always have much more closely-spaced stops … and why Walker’s bus heaven substituting for Metro won’t ever work. Buses should be short-route feeders to proper Metro.

        • Eric

          “Buses should be short-route feeders to proper Metro.”

          Except that many routes, for example most circumferential routes, will never have the demand for proper Metro.

          I suppose you could make a two level bus system – a Walker style grid of fast routes, overlaid with a bunch of short feed routes with grid stops for old people only.

          Although I sort of expect autonomous cars to satisfy the latter need.

          • Eric

            “short feed routes with grid stops”
            *with closely-spaced stops

          • Michael James

            Eric 2018/04/15 – 02:22

            “Buses should be short-route feeders to proper Metro.”
            Except that many routes, for example most circumferential routes, will never have the demand for proper Metro.

            Exactly the point: buses feed from a large catchment to a (radial) Metro, ie. instead of attempting long routes into the centre (or anywhere really). The problem is when city transit planners crayon out long bus routes with a zillion stops that takes forever to get anywhere–but it looks “efficient” to them (one bus, one driver, covering a lot of territory) but it is exactly what users hate about buses. And because the planner is trying to save money a long route inevitably means low frequency and you get the worst of all worlds.

            I suppose you could make a two level bus system – a Walker style grid of fast routes, overlaid with a bunch of short feed routes with grid stops for old people only.

            My city has something like that. There is a considerable busway BRT and also special semi-express buses that only stop every km or so (or in some cases 3-5 km once on the BRT ROW routes). Ordinary buses run the same routes with much more frequent stops. Naturally there are only these semi-expresses on heavily-trafficked routes.

          • Alon Levy

            In Brooklyn, there’s one local bus that enters the center, a short-hop route crossing from Williamsburg to the Lower East Side on the Williamsburg Bridge. Nothing else goes into Manhattan. So in a way the system in Brooklyn already feeds the radial subway.

          • Michael James

            Alon Levy 2018/04/15 – 13:49

            Nothing else goes into Manhattan. So in a way the system in Brooklyn already feeds the radial subway.

            Sounds good. Pity the subway doesn’t seem up to the job, but that is no reason to clog the busiest roads with ever more buses to clog them even more. I am a big fan of banning buses entirely from inner-cities. They are self-defeating as this fave pic shows (never tire of showing this):

  4. James Sinclair

    I think Jarrett Walker severely underestimates the transfer penalty for riders. In a market like Houston, a transfer might mean getting off a bus into the grass (no sidewalk), crossing a 6 lane arterial twice (with no crosswalks), and waiting in the hot sun with 90% humidity in the grass with no shelter or bench. It doesnt matter if a bus comes every 10 minutes, it absolutly sucks.

    Unfortunately, he looks at transfer in the context of downtown Portland, and not what 90% of the country looks like.

    For Brooklyn, the transfer penalty wouldnt be about infrastructure, but about safety. If you’re a woman, you dont want to get off your bus in Flatbush at night and wait at a corner for ten minutes. You will be harassed, every time.

    The good folks at Citymapper, Google Maps etc do not include traffic or crime safety in their recommendations.

    Disclaimer: My gf lived in Flatbush and she would ride the 2 and transfer in Manhattan instead of the direct Q because she did not feel safe walking a certain 2 block stretch near her closest Q stop.

  5. Mike

    Important topic. I’m surprised Toronto isn’t mentioned more when talking about the undoubted importance of frequency in large urban public transport markets. Check out their published schedules. They are remarkably frequent for a North American city and on a par or better than many in Europe. Wider stop spacing is very important for raising the attractiveness of public transport. It needs to be done. There is a wide variety in London with formerly tram and trolley bus routes having shorter spacing than those who have only ever had diesel buses. My local bus has an average stop spacing of 450 metres between my house and the tube and the speed benefits are obvious.

    • Alon Levy

      Yep! I’ve been thinking about this issue for a while and I definitely did notice how frequent the Toronto grid routes are. Then I learned that things are even more frequent in Barcelona, and that Barcelona deviates from the grid to serve major destinations (relevant to less strictly gridded networks like Brooklyn, where deviations are unavoidable)…

      What’s the stop spacing in Toronto? Vancouver has an American stop spacing patterns: locals every 200 meters, limiteds every 800-1,000.

      • Mike

        In the outer areas with wider roads and less congestion the speeds attained by TTC buses are surprisingly fast. But although buses didn’t stop at all stops unless requested spacing seemed fairly close. A bit wider than standard North America but not much. However in the inner city I found tram stops ridiculously close. This was compounded by having Sunday only stops even closer! I believe these have now been dispensed with. I’ll check my notes to see if I can come up with some more data.

    • johndmuller

      Mike posted:
      Wider stop spacing is very important for raising the attractiveness of public transport. It needs to be done.

      Attractive to whom??? No way are you going to be able to sell the riders on the supposed benefits of walking an extra block or two at either end versus the supposed decrease in trip time. There is no control bus running the other stopping pattern to prove this point while these improvements may in fact be belied by watching the bus sit in traffic anyway at the location of your would be stop. Fortunately, many bus drivers will let you off rules notwithstanding at a non bus stop if they happen to be stopped anyway (not generally so kind about getting on; in fact sometimes not even accepting passengers waiting at actual bus stops – which behavior one might want to factor into the desirability of greatly increasing the need to transfer).

      That is to say – messing with the stop spacing does little to improve trip time if traffic congestion is the primary problem. I’d like to take this opportunity to give a nod to Baltimore for (at least in the past) biting the bullet with tough (no)parking restrictions and nasty enforcement (i.e. towing) to keep the main routes pretty open for the most part – even to the point of it being somewhat disconcerting/dangerous for pedestrians on the sidewalk having cars and trucks and of course buses zooming by at speed in the curb lane, not something you are necessarily ready for.

      • Mike

        John I am a rider and non car owner here in London. I absolutely want faster journeys on the bus and not having stops situated a stones throw from the previous one is one way to achieve that. We don’t have congestion all the time and it is excruciating to sit on a bus as it lumbers away from a stop only to start braking immediately as it nears the next one. This isn’t the way forward to making urban transit attractive enough to go for modal shift.

  6. lake9856

    Off-board fare collection in San Francisco? Really? I thought you tapped your clipper card as you boarded the bus. Of course, you can enter in any door if you tap your clipper card. It’s more efficient boarding than having everybody dip their Metrocard and come through the front door, but it’s not the same thing as off-board fare collection.

      • FDW

        With MUNI, if you don’t have a monthly pass, you should tap. If you haven’t used your monthly pass yet, you should make sure to tap the first time around. AC Transit, VTA, and SamTrans are pretty similar to MUNI in terms of what you should do. On the other hand Golden Gate Transit (along with Caltrain), you need to tap when you get on, and when you get off.

    • FDW

      MUNI has off-board fare collection for MUNI Metro, but the tickets from the machines can also be used for buses.

  7. Pingback: The MTA’s Bus Redesign Plan | Pedestrian Observations

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