According to the latest plans for Maryland’s Purple Line, it will have the longest transit railcars in America. Each train will have a single 136-foot-long five-segment railcar. They’ll practically be open-gangway trains.

Purple Line trains will be Urbos model trams, built by Spanish company CAF. Urbos trams are modular; you can make them as long or as short as you want. These will be unusually long ones.

At 136 feet long, they’ll be 2 feet longer than the closest US competitor: Austin Metrorail’s 134 foot cars. But Austin’s cars are DMUs, a sort of commuter rail / light rail hybrid, built for longer distance and fewer stops compared to the Purple Line.

The next biggest US light rail cars are Dallas’ 124 foot cars.

Longer is better

Having one long railcar rather than multiple short ones has a lot of advantages. There’s less wasted space between cars, less expense per rider, and passengers can move back and forth inside the train to find the least crowded spot. Overall, having one long open interior increases the capacity of a train by about 10%, and it costs less.

The downside is you can’t pull individual cars out of service if something goes wrong. It’s all or nothing. But as long as everything works, long railcars are great.

Since the Purple Line will be operated by a private company that faces penalties if it doesn’t meet service requirements, the onus is on them to keep trains in service.

In transit jargon, these open interior trains are called “open gangway, ” and almost everyone else in the world uses them, except the United States. For the Purple Line to move in that direction makes it a national model.

Using these long trains was one of the changes project officials made in response to Maryland Governor Hogan’s demands to reduce the Purple Line’s costs. One long railcar rather than two short ones coupled into a train saves money and keeps train capacity high enough to work.

Hogan’s other changes made the Purple Line a lot worse. They reduced train frequency, eliminated the direct transfer to Metro at Silver Spring, and reduced the electrical power of the line, limiting its capacity. But the move to longer railcars with open interiors may be a silver lining.

Comment on this at the version cross-posted to Greater Greater Washington.





