Saturday, June 20, 2015

Boston will not have "Gold Level" BRT: the streets are way too narrow

I'm digesting the study from Boston BRT from the ITDP group (second installment on the actual capacity of BRT here) and while I certainly appreciate forward-thinking planning in transit, I feel that they are selling us a bill of goods in several aspects. One is promising that Boston can cheaply and easily have a "Gold Level" bus rapid transit, a level attained only by a handful of South American cities. The problem is that Boston's street geometry and grid do not allow for that level of service, even by the ITDP's own scorecard. We shouldn't marry ourselves to an artificial and unattainable standard, but we should build the transit system that we need.

The scorecard is out of 100 points, and you need 85 to meet the gold standard.

Here are the Boston BRT's routes, and their highest possible scores (within reason, anyway) based on the detailed ITDP scorecard:

CriteriaPointsBlue Hill AveDudley-DowntownHyde Park AveDudley-HarvardDudley-SullivanNotes
Dedicated Busway875555Assumes separated lanes for 75% of BHA, and colorized/exclusive lanes for 75% of other corridors.
Busway Alignment885555Assumes an average of 5 points for corridors other than BHA.
Intersection treatments755222Will be hard to ban turns across busway outside of Blue Hill Ave corridor. Assume some turns prohibited and signal priority.
Multiple Routes444044No other buses use Hyde Park Ave
Demand Profile322333Highly dependent on high-demand areas, which are often the most space-constrained. 
Center Stations221011Center stations + lanes require 32 feet of width.
Station Quality32211110 foot required width unlikely at all stations in narrower corridors.
Pedestrian Access330000Requirement of 10 foot sidewalks rare in Boston.
Bicycle Parking211100Standard of bike racks in most stations unlikely.
Bicycle Lanes211111Some bike lanes qualify for one point.
Bicycle Sharing100011Requires bike sharing at 50% of stations.
Systemwide554747474747See Below

Systemwide points assumes that Boston could qualify for full marks in a variety of categories, i.e. there are no physical constraints: operating hours (2), comtrol center (3), platform level boarding (7, although this may be difficult on downtown corridors), top-ten corridors (2), multiple corridors (2), emissions (3), intersection setback (3, assuming exceptions for frequent short blocks), pavement quality (2, although whether a 30-year pavement is attainable in New England's climate is unknown), station distance (2), 2+ doors (3), branding (3), passenger information (2), accessibility (3), system integration (3).

Systemwide points where Boston would not qualify for full marks: fare collection (7/8, assumes full proof-of-payment system; otherwise it requires turnstiles at each station), express-local service (0/3, requires passing lanes), passing lanes (0/4, requires wider streets), docking bays (0/1, requires passing lanes).
Given these scores, the highest corridor scores 82, three points shy of gold standard, and that's being quite generous in some categories (i.e., it will be tough to ban turns for most buses, or squeeze in bike lanes in already narrowed corridors, and I'm still not sure why renderings along, say, Hyde Park Avenue don't show stations, which take up a good deal of space). Two other corridors make the silver standard of 70 (barely), and the others are bronze. Even still, it would be a lot of work to shoehorn in enough ITDP-standard busway to meet that. Mexico City, which the report uses as a model, doesn't even reach the gold standard on any of their lines, despite most of them running in streets wider than in Boston. In the US, only Cleveland has attained silver level, and Euclid Avenue there is mostly 80 feet wide (110 feet between buildings) and the narrowest parts are 60 feet wide. We need to have better-performing buses in Boston, but we need to adapt what works in other cities, not wed ourselves to a metric that is ill-suited to our city.

I sketched the BRT networks in Bogotá and Mexico D.F., showing the curb-to-curb street width of each street where BRT operates. I divided the streets in to five categories:
  • 130 feet or wider. This is the majority of street widths in Bogotá. 
  • 100 – 130 feet. This is the minimum width in Bogotá except for two short portions: a narrow portion to a terminal downtown on a bus-only street (which is still 50 feet wide at its narrowest) and the southern portion, which runs non-stop through an undeveloped area to a terminal station. This is generally the minimum for passing lanes at stations.
  • 75 – 100 feet. This is the minimum width of most streets in the Mexico City network. Few Boston streets are even this wide. This generally permits single-lane stations, but not stations with passing lanes. This is the bare minimum width for a "Gold Level" BRT (although Mexico's system is rated "silver".
  • 55 – 75 feet. This is the minimum width of any BRT line in Mexico City. This is the minimum width for a complete street with two lanes of BRT, a station and either two lanes of traffic or one lane of traffic and bicycling facilities.
  • Less than 55 feet. There is no way to fit BRT on a street this wide without removing all but one lane of traffic. While BRT can run on streets of this width, they have to be in areas which do not require any auto access, and nearby streets need to be able to host adequate bicycling facilities. In a city like Boston without any street grid, this is often difficult to provide. There might be a it of fungibility at the high end of this scale—something like the 53-foot-wide Harvard Bridge which could have a bus lane, a travel lane and a bike lane on each side, barely—but only in areas that don't require any stations, at which point it's just too narrow. 

One of these things is not like the other. Much of the supposed gold standard BRT route network in Boston is simply too narrow to have gold standard BRT. It's also worth noting that while in Bogotá and Mexico BRT runs in relatively straight lines, in Boston, outside of Blue Hill and Hyde Park avenues, it's much more serpentine. This is because of the cities' unique geographies, and it doesn't make sense to establish a single "standard" when each city is inherently different.

Here's a fun game, called "where do you site the station?"
Because people do have to get on and off the buses somewhere.
Oh, and a street segment like this would require cars to turn
across the busway to access driveways.
In the ITDP's 25 page report, here's what they say about street geometry:
Boston has a unique cityscape, and while the ITDP analysis shows that Gold Standard is possible, there are stretches where routing would pose a challenge. For example, tight passages can still accommodate BRT, but in some cases a street may need to be made BRT-only, or converted to one-way traffic.
They also admit that it might be a wee bit harder to fit "gold standard" in Boston:
It’s important to note that all of these travel time projections are based on implementing BRT at the gold standard throughout the entire length of the corridor. This study acknowledges that achieving every element of Gold Standard in a few portions of some of the corridors would require some bold steps. The exact corridor routing and any associated trade-offs will have to be explored in more detailed analyses in the future.
Yet their travel time savings analyses (appendix C, here) assume median bus lanes. From Dudley to Harvard most of their savings come from congestion reduction:
Median-aligned dedicated BRT infrastructure will greatly reduce the 20.6 minute delay associated with congestion. 
Yet most of this corridor is too narrow to support median bus lanes and stations. (Not to mention that by analyzing the 66 they choose the longest possible Dudley-to-Harvard route—the 1, CT1 or Silver-to-Red Lines are all faster—and 66 bus schedules to Harvard include schedule padding for the loop through Harvard Square.) Yes, in theory, most of the corridor could have such lanes, but only if a single lane were left for vehicles, driveway access and loading, to say nothing of bicyclists. That's just not going to happen.

So, they acknowledge that street width might be an issue (read: probably impossible), but that's something to be studied in the future, but the numbers assume that it's a done deal. (More studies! More money for the ITDP!) This is intellectually dishonest. If something isn't going to work, it should probably inform your study. This would be be like if someone studied a high speed rail line and said "do note that because we can't plow straight through a major metropolis, the exact corridor routing might be slightly longer than analyzed" but then analyzed the straight line distance anyway.

Look at the maps above. Street width is a slightly bigger problem than they make it out to be. It comes down to the fact that the highest performing bus rapid transit lines are built in cities which already have a lot of room to work with. Boston is much less like South America or Asia (newer cities with wide roads) and much more like Europe (older cities with more constrained rights of way). There are not many ITDP busways in Europe.

More to come on such topics as where we should have BRT in Boston, how we should go about implementing it, and what we should implement in corridors where BRT is not workable. But suffice to say, we should not paint ourselves in to a corner by adhering to an arbitrary standard like the one from the ITDP.


  1. I don't like the ITDP standards sometimes because a lot of what they think is "Gold Standard" is also anti-urban. Bogota's BRT line might as well be a freeway in some parts with how it integrates into the urban environment.

    1. Very good point. A 110 foot wide street takes more than 30 seconds to cross for an average walker, to say nothing of an elderly or mobility-impared person. A 150 foot wide street takes nearly a minute. This sort of BRT only works when you have barriers in the middle of wide streets, making pedestrian travel much harder. Light rail can attain the same capacity with a much narrower, more walkable street (see my next post, or Calgary: 20,000 passengers per hour in a <40-foot-wide street). Bogota's BRT line is basically in a freeway. Light rail can interact with the urban environment while still having high throughput, as can anything underground (and at some point, it makes sense to bite the bullet and put transit underground). Bogotá happened to have a bunch of very, very wide roads for their transit system. Without those, you never get the capacity. But with them, you have a fragmented urban fabric.

  2. The thing is, we've already built the most important, tricky, and expensive parts, on the narrowest and most congested streets. In fact, Boston has the foresight to do that almost 120 years ago with the Tremont St Subway, which still has spare capacity for services coming from the direction of the old Pleasant St. Portal.

    Also, light rail has some hard geometric advantages on narrow streets, even disregarding the issue of capacity: the trains don't need to steer, so tracks can be spaces somewhat closer than lanes. And since trains are on rails, the back of the train follows the same curve radius as the front, unlike buses where the rear wheels follow a smaller turn than the front, and so require big sweeping spaces to make sharp turns, which results in 20 foot wide slip ramps that are annoying and dangerous for pedestrians (just look at the geometry around Silver Line Way).