Wednesday, July 16, 2014

The next person to say "The same as 1897" …

Every so often, someone knocks the MBTA. I know, I know, it's shooting fish in a barrel. But sometimes you hear that the T built the first subway in 1897, and hasn't made any real improvements since. (I'm looking at a certain "disruptive" transit service here: "Between 1897 and right now, there’s been some marginal improvements in how service is delivered to move massive amounts of people throughout a city.") In 1897, the underground transit in Boston was composed of streetcars. Mostly short streetcars. Here's the article about the first streetcar through the tunnel: a car from Allston via Pearl Street. Here's that streetcar (or one like it): a 29-foot car. Back then, a parade of 25-to-30 foot vehicles (most of them just eight feet wide) plied the subway. It was better than the gridlock at the surface, but didn't have a huge capacity.

By 1901, the Main Line Elevated operated first through the current Green Line tunnel, and by 1908 through its own tunnel. These ran four-car trains of 65-foot cars that were 9 feet wide—still narrow, but much larger than the 1897 cars.

In 1912, the Cambridge-Dorchester tunnel (The Red Line) opened in 1912, and the Orange Line cars had proved inadequate for the crowds, so the T opted bigger. These cars were 69 feet long and 10 feet wide, triple the size of a streetcar one level up at Park, but operating in four car trains. The tunnels were wider too, with fewer curves, allowing faster operation. In 15 years, there were trains an order of magnitude larger than the first iteration.

(A similar thing happened in New York: the IRT cars—in 1904—were built to approximately the size of the Orange Line fleet, by the time the BMT built their tunnels ten years later, they were using Red Line-sized cars.)

But let's go back to the Green Line. It took a bit longer, but the Green Line trains grew by an order of magnitude, too. By the 1940s, they were running three-car trains of PCCs, 47 feet long and more than 8 feet wide. In the 1970s, the first articulated vehicles showed up, and current Green Line trains are 8'8" wide, and 74 feet long. And they operate in three-car trains. That's 222 feet long—quite a bit longer than 29 feet—and, overall, nine times as big. It took some time—three car trains have only started running recent years—but the Green Line has improved capacity an order of magnitude, despite the 115-year-old infrastructure.

Oh, right, in 1897 (and 1997) you paid with a coin, now you pay with an RFID card. And sometimes the trains even have air conditioning! But that's another story.

In other words, knocking rapid transit for "marginal" improvements in the last 115 years isn't disingenuous: it's wrong.


  1. I think there's definitely been some improvements since 1897, but there are definitely things that were achieved then that have since regressed. For example, right now, the Red Line is just about maxed out at 13 trains per hour (though they are 6 car trains) while back in the 1920s, the line ran 34 trains per hour which was a much higher capacity even with 4 car trains. As for the Green Line, it probably has a higher capacity now than it did back then, but it also serves considerably fewer areas. The original subway had cars going to dozens of destinations, now we only have four.

  2. Also works the other way. I'm kinda sick of hearing the MBTA make excuses by claiming their subway is from 1897...

    No, it's not. Not anymore, and not for a long time.

  3. Agreed that it's not an excuse for the MBTA to complain—although when people compare it to brand new light rail systems you do need to give them some credit. It is the most used, and oldest, system in the country.

    The Red Line headways are somewhat hampered by the longer distance it travels now. Until 1984, the Red Line started in Harvard Square. By the time it got to Charles it had made only two stops, including Kendall, which was, for much of that time, a declining industrial area. Now? Trains pass through Alewife, Davis, and Porter, and if they hit timing for bus transfers just right, can be filled before they get to Harvard Square. This means that there are increased dwell times at stations, and running a train one minute behind means you'll have a full train followed by an empty one.

    In other words, at a certain point, there are diminishing returns by running more service, especially on a line which has spiky demand (transferring traffic) and not a steady flow (access from neighborhoods, parking facilities). Buses have the same issue: run them close together without signal priority, off-board payment and exclusive rights of way and it's nearly impossible to keep them from bunching. Single-track heavy rail lines (like the Red Line) have a very high capacity, but a finite capacity. The Red Line is probably the most heavily-traveled subway line in the country outside of New York, and it is approaching that limit.

    1. In terms of headways, WMATA runs 26 trains per house through the Rosslyn tunnel, which is twice what the Red Line manages, and the BART trunk line has around 24 trains per hour at the peak. I'm not sure length of the line really matters for headways: if anything, having more ridership concentrated at fewer stations means longer dwell times.

      For a rail line, headway is the sum of three components: dwell time, platform clearance time, and platform reoccupation time. Clearance time is determined by the acceleration of the trains, and the Red Line does okay on that. But on the other two components it doesn't do so well. In particular, dwell times can get rather long, especially on the older trains that have only three narrow doors per side, rather than four wider doors, and especially at stations like Downtown Crossing where there's a relatively narrow platform with a transfer at the very end, which causes congestion and slow boarding/detraining at that end of the train. And finally, the time between when the train leaves and when the next train enters the station is far, far too long: on the order of three and a half minutes in the Downtown part of the subway where trains are limited to 25 mph anyway and safe braking distance is less than a train-length. As for bunching, the problem is that dwell times get longer as trains get more crowded, which delays the trains and makes them even more crowded. Running more trains keeps the crowds from building up to the point where they start delaying trains.