I was visiting Boston last week, and am in New York this week; you can see me at NYU on Thursday tomorrow. Last week, I met with TransitMatters activists talking about bus and rail improvements in Boston, and on the way saw something that made me understand two things. First, the MBTA is run by incompetent people. And second, even two subway lines that are perpendicular and serve completely different areas can be redundant with each other.

Two and a half years ago, I said redundancy is overrated. In this post, I’d like to argue from the opposite direction: transit networks have more redundancy than they appear to. One implication is identical to that of my older post: transit agencies should build subway lines without regard for redundant service, since not only is redundancy overrated, but also a new subway line is redundant with old lines even if they serve completely different areas. But the other implication concerns service interruptions and shutdowns.

The issue in Boston is that, although there are nighttime shutdowns, there are also occasional weekend shutdowns, as in New York, for major capital projects. The Red Line is being closed on weekends for two months on the segment between Boston proper and Cambridge. But the Orange Line is also being closed on weekends on segments, after deferred maintenance led to a meltdown in the last two months, with frequent delays and slow zones. Last weekend, I found myself having to go between Davis Square (on the Red Line, just off the edge of the map) and Jamaica Plain (near the bottom of the Orange Line) to visit Sandy Johnston, with the highlit segments shut down:

Shuttle buses replaced the subway on both segments. On the Red Line, the MBTA contracted it out to a private company that used wheelchair-inaccessible high-floor buses; there were not enough MBTA bus drivers to run the shuttles on both segments, and by union rules the MBTA could not use contract drivers on its own buses even though it did have the equipment, forcing it to use inferior private-sector buses. I am able-bodied enough to climb high-floor buses, but I would not use the shuttle buses replacing the Red Line for another reason: as can be seen in the map, there is no continuous street grid between Charles/MGH and Park Street. If there were a crossover right east of Charles/MGH then only the Kendall-MGH segment would be bustituted, and there, the buses would go on Longfellow Bridge, with a serious but not fatal slowdown. But between Kendall and Park Street the buses have to swerve through side streets that were not designed for fast traffic; in 2012, I was on such a shuttle and as I recall the trip took 15 or 20 minutes, where the subway does it in about 5.

Instead of relying on shuttles, I took a bus north of the river to get to Lechmere and use the Green Line to reach Chinatown on a chain trip. From Chinatown the options were all bad, and I rode the 39 bus, which parallels the Green Line E Branch (the southernmost one) and continues south to Forest Hills, where the Green Line once ran as well. The way back was not a chain trip, and with a bus-bus-Red Line trip and no 39 bus in sight (the online bus tracker was down), I gave up and took a taxi.

The Red Line and Orange Line look like they go in different directions, so shutting down one does not affect the other. But in reality, in a city with buses, taking the bus to a different line is a common strategy to deal with shutdowns – hence, using the Green Line to get between Davis and Chinatown, taking a bus in a place where the buses are less slow than between Charles/MGH and Park Street.

If any city in North America did not use buses at all, it would be Boston. It has legendarily narrow and twisted streets, and crawling buses. It has higher rail-to-bus ridership ratio than any other American city except possibly New York, and far higher ratio than the major English Canadian cities with their bus grids. Its transit network, inherited from midcentury, uses the buses to feed the subway, and has no bus service through downtown, where even before mass motorization there were traffic jams of streetcars.

But even in Boston, using the bus outside the core to get to a better subway line is possible, and normal when there are service interruptions. This means that any pair of subway lines could potentially be redundant with each other. This means that it is bad practice to shut down more than one line at once for repairs. The reason the Orange Line needs emergency repairs in the first place is that the MBTA maintained it poorly and wouldn’t act when it was less urgent, such as six months ago (Sandy reports noticing a consistent deterioration in service since January). Today, the shutdowns are probably unavoidable. But the Red Line shutdowns, for a capital construction project involving the Longfellow Bridge, can be delayed. The MBTA should do that in the future in order to both avoid having to use inaccessible buses and allow passengers to take a circumferential bus to a functioning subway line.