Silver Line, downtown to Mattapan; Washington Street and Blue Hill Avenue. This is broken in to two routes in the ITDP study, but really they combine as one. And this is an incredibly important transit corridor, linking a huge swath of lower income neighborhoods in Boston in with the downtown core. Better transit would serve these communities well, and increase transit-accessible housing in the region dramatically. This is important in curbing gentrification by dramatically increasing supply so that demand, latent and induced, can keep pace.

And this is a good candidate for bus rapid transit! South of Warren Street, Blue Hill Avenue is more than wide enough for a high-quality BRT system. North of there, there are constrained sections, but only a couple of major bottlenecks (Warren Street, just north of Dudley Square). But there are two major issues with bus rapid transit on the corridor. First, it might hit capacity, like the Orange Line in LA has. Without grade separation or passing lanes (neither of which are feasible, especially in the more heavily-used northern portion of the line) better-than-three minute headways are difficult without without bunching and load balancing issues. And with narrow roads downtown, even 60 foot buses are a stretch, longer buses would be difficult even if they were used in the US.

Second, downtown. Boston had a problem with surface transit clogging downtown 120 years ago. We solved it by putting transit underground. I’m very on the record as saying that buses are a good thing in downtown Boston. But with narrow streets and limited terminal space, downtown Boston doesn’t need more buses, especially buses which need to maintain even headways in both directions; most of the current routes are express buses which carry few people on their outbound trips; others mostly use the already-busy Haymarket busway. (I’ve written ad nauseum about the perils of scheduling a busy route without recovery time at both ends.) We certainly shouldn’t banish the buses we have, but we also should be wary of too many more.

What makes sense for this corridor is light rail. It can also deal with a few short street-running segments (although the ITDP would believe otherwise: see page 22 here where they sell BRT because it can run in mixed traffic while light rail cannot; this is patently untrue) and has higher capacity. But the major advantage is that instead of threading through narrow downtown streets, light rail can use existing infrastructure and use the subway along Tremont Street to reach Government Center and beyond. As someone commented to me, we solved the issue of running transit on downtown streets 120 years ago. Well, more like 118.

Is there capacity in the subway? West of Boylston, there is not. But from Boylston to Park Street, there are four tracks, and the inner two tracks which come in from the west are separate from the outer two tracks, with a turning loop to send cars back. So by terminating some cars at peak hour at Park Street, it would open capacity to have cars from the now-abandoned Pleasant Street incline in their slots. This might mean, at rush hour, turning B cars at Park Street. Some B Line riders might have to make a cross-platform connection to high-frequency through cars for the trip to Government Center (where they terminate today), but it’s a small price to pay for proper underground service.

And if you do that, you don’t have to try to engineer BRT on to narrow downtown streets where it doesn’t belong. In Mexico City, Line 4 is the only section on similarly narrow streets, and those streets have no vehicular access to businesses, something that would be difficult to implement as most streets in Boston require deliveries made by vehicle. Even so, that line in Mexico can only run 40 foot buses, platforms have few of the amenities associated with BRT (there’s nowhere to put them) and capacity is constrained. The report’s “technical analysis” spends a lot of time examining how to route BRT downtown by completely taking over streets, which is basically a non-starter. I’m not sure how businesses in the Centro Histórico are serviced (parallel streets, perhaps) but for most areas of downtown Boston, there needs to be at least some vehicular access to the streets, especially since the Centro Histórico is more akin to the North End than the Financial District. In any case, this is probably a nonstarter on downtown streets in Boston.

Yet the cost of rebuilding the Pleasant Street incline is certainly not inexpensive. Both downtown solution are costly, yet one only integrates with existing light rail capacity and another only with BRT. Perhaps the solution downtown, right now, is to do the minimum. Run buses on the Silver Line route, perhaps with better lane priority, but don’t try to carve out BRT through the Financial District for a high cost and low return.

And south of that point? Do everything. Build a true light rail-ready BRT corridor. In name, San Francisco is doing this on Geary, but conversion would still require the removal of concrete and the installation of electric capacity, both of which would be disruptive to transit operations for some time. If you are going to completely rebuild the street (which either mode would require) put in the disruptive infrastructure for the future. The marginal cost of setting rails in concrete is minimal (and some portions would be used by buses even if light rail trains ran as well), and if you’re already digging down, building the necessary electrical conduit system costs a lot less (substations can be added later). Then, if and when money becomes available for the Pleasant Street incline (which may dovetail with capacity constraints), you can easily convert the corridor to light rail operations without digging up your investment.

It’s also more of a commitment to the community. One of the reasons (I believe) the 28X proposal was sunk is that it was an inferior product in the neighborhood without any promise that it would ever be comparable to rail service. The current study does little to quell those fears, especially since the Silver Line is often full and the bus lanes it uses disappear where they’re needed most downtown. The 2012 study of modes that made the curious assumption that a light rail line with one-seat rides downtown would actually decrease transit use was further “proof” to community activists that the deck was stacked against rail transit. (This may be due to fewer transferring passengers, so there would be more overall journeys, but fewer unlinked trips. Of course, this is coming from an agency which defines highway capacity by the number of vehicles moved per hour, not the number of people (!) so take it with a grain of salt.) And proposals for limited-stop buses along the 28 (from the same study) still don’t promise a one-seat ride downtown, although at rush hour, considering the chance of getting a seat on the Orange Line at Ruggles, it might be a good descriptor.

Building a light-rail ready line, and actually putting some track in the ground, would be a commitment that, yes, the goal is a system which integrates with the rest of the transit network. The fact that there is spare capacity in to Park Street is icing on the cake. For much of the T, getting more capacity would require major track and signal upgrades. But the tracks at Boylston are there, and the quad-track running in to Park could allow for additional service.

Yes, this will cost somewhat more. But light rail doesn’t cost that much more than bus rapid transit, and if you don’t string wire, add substations or buy vehicles, it pulls the cost down further. Steel rails only cost so much. But you won’t be stuck in a Orange Line-esque sunk cost conundrum like in LA. There, the initial cost to build BRT plus the cost to upgrade it is nearly the cost of tearing it out and putting LRT in it’s place. It’s a sunk cost white elephant. Don’t build that here.

Neighborhood street with no parking or bicycling facility. Also, no room for a bus station. Yup, this makes sense.

Hyde Park to Forest Hills (32 bus). Here’s a line appropriate for BRT … if the street was wider. As it is, there would be enough room on much of the corridor for BRT, travel lanes and, well, that’s it. If there were a parallel street for, say, bike lanes, that might work, but there’s not. Hyde Park Ave is the main artery through the neighborhood, and it needs to be a complete street. The ITDP’s proposals leave enough room for one travel lane, or require one-way splits which are poor transit planning, especially if there’s a barrier (the Providence Line) in between. There is also no plan showing how to fit a bus stop in to to these narrow areas. Presumably everyone will walk a mile to wider parts of the street as empty buses roll through?

Then there are other users. There is, apparently, no need to have provisions for cyclists in Hyde Park Ave. We often talk about making streets more comfortable for cyclists, and a single travel lane shared with cars is certainly not a high level of comfort. This is also not somewhere where bike/bus lanes make sense, as buses would be slowed by passing cyclists more than they are in traffic (more on this later; in some short segments they do make sense). So to speed buses, all cyclists will either have to poach bus lanes, risk narrow travel lanes with no shoulders, or take a circuitous route. More likely, they just won’t bike. And let’s talk about parking. This is a neighborhood street. It would be great to give people a BRT option, but you can’t build a street with zero parking. Not just politically. At all.

Is what is proposed even gold standard? Not even close. By the ITDP’s own standards, I doubt this corridor would score higher than the bronze level. Would the 32 benefit from stop consolidation, proof-of-payment fare collection, better stop amenities and bus lanes on the wider part of the corridor? Certainly. Again, to make an analogy to the Twin Cities, this is exactly what they’re doing with the 84 bus on Snelling. Fewer stops, better amenities, off-board fare collection. Costs a lot less, gets most of the benefits. Perhaps those are the steps to take, not pushing through a politically unpalatable busway which will anger drivers, cyclists and pedestrians, and which won’t have much marginal benefit.

Dudley to Longwood and Harvard/Sullivan. Like the Downtown-Dudley-Mattapan corridor, this is one of the most important corridors in the city. It links several transit lines with major employment centers, both current (Longwood, Kendall, Harvard) and upcoming or potential (Sullivan, Dudley, and nearly Assembly). But there are no wide roads between them, and the roads that do exist have numerous pinchpoints and bottlenecks. Constructing bus rapid transit would be a massive undertaking (The urban ring proposal was for a mile-long tunnel below the Longwood area, perceived as “the rich get their tunnel and the poor get pollution.” If you’re going to build a tunnel, as we’ve seen with the Silver Line, don’t hamstring it with low capacity bus service.) and still would be serving as a major crosstown and last-mile route with high and imbalanced peak transfer loads, resulting in a system unable to cope with capacity.

It has two potential outcomes which the Silver Line illustrates well:

• The SL4/SL5 scenario. A watered down BRT that will fail to deliver the promised time savings. This has happened on the SL4/5 from Dudley to Boston. It doesn’t have enough signal priority, street width, or enough priority in congested areas (where it really needs it) and is barely faster than the bus lines it replaces (the CT2 and others). It hobbles along with relatively strong ridership, but never really attracts new riders or takes pressure off the downtown subways or achieves the time savings to attract new riders who currently drive. This is the far more likely scenario. It is notable that even the ITDP’s rosy predictions for this route offer only modest time savings.
• The SL1/SL2 scenario. There is money and political will to build a proper BRT system: full signal preemption, elevated platforms, 60 foot buses, significant grade separations, the whole nine yards. We don’t have the street width for passing lanes, so the system is run as a single line. There are quickly diminishing returns once you start running more than 20 buses per hour per direction and it’s very unlikely that you can get beyond 30 buses (one every two minutes): minor fluctuations in passenger loading will quickly cause bunching. Considering that the corridor acts as a last mile transit line for several major subway and commuter rail lines, this is all but inevitable.

  So you get a white elephant: spending a lot of money (the SL1/2 cost $625m in 2004, equivalent to $800m today, or about half the cost of the GLX, with much lower throughput) and quickly go over capacity with no way to add more. The 32 buses hourly in the Silver Line waterfront tunnel have a theoretical crush capacity of 3,200 passengers (less, actually, given the luggage racks in the SL1, and bunching and delays as the buses can’t handle influxes of transfers at South Station). This is significantly less capacity than a single branch of the Green Line (which could be more efficient with fare pre-payment and signal priority), and less than a quarter of the combined capacity of the Green Line central subway, which, with 37 trains per hour carries more than 12,000 passengers. If the Green Line ran all three-car trains, it would have six to eight times the capacity of a BRT line.

Above: major and emerging employment centers outside of downtown (green, blue), other employment/activity nodes (pink circles), Commuter Rail stations (purple circles). On the left, current transit routes and demand, on the right, how two new rail lines would satisfy most of this demand.

Obviously, just a sketch, but it’s likely something could be fit in to the existing Harvard station without completely rebuilding it a la 1978-84.

So you’d have to do some construction in the station. But this might actually be quite easy. The main issue is that to build a full wye, you’d need to have some trains switch levels, which doesn’t exactly work. If you didn’t have a Central-Allston leg of the wye (which you don’t really need, but which you could retain for non-revenue moves), trains could operate through the existing platform and then have a switch just east of the platform end and a curved tunnel to the existing tunnels (with a less-severe curve than the current line). All of this could be built within the existing station cavern. The major change necessary would be to relocate the stairwell from “The Pit” in Harvard Square, but that could use an update after 30 years anyway, and it could potentially be built in between the bi-level tracks (see sketch). Beyond there the tracks would be left-running (think Britain) but the line could fly over itself somewhere (cut and cover in Allston, or perhaps in the bored section) to regain right-side running for the connection to JFK/UMass.