New York City's subway system is among the most expansive, popular, and best in the world. It's also insufferably crowded and ill-equipped to handle the rising ridership that comes with the city's growth. But there's hope for a subterranean transit future that doesn't look like rush hour in Tokyo: the Metropolitan Transportation Authority will experiment with open gangway cars.

It's a simple trick used all over the world to ease crowding and reduce delays. Like on an articulated bus, individual cars aren't divided. In other words, the space between cars becomes usable, increasing a train's capacity without adding length. And right now, anything that lets more people ride New York's subway is a very good thing.

The city's population is expanding in Brooklyn and Queens, straining a system already at capacity. Subway ridership on the system has spiked in recent years to levels not seen since the late 1940s. The MTA saw ridership climb 2.6 percent between 2013 and 2014 to 5.6 million riders each weekday. All told, the system served 1.8 billion trips in 2014.1

In response, the MTA has increased service and launched more bus rapid transit. It's also expanding the subway system, building the Second Avenue line and extending the 7 line from Times Square to the west side of Manhattan. Those projects, however, are almost prohibitively expensive—the first phase of the Second Avenue project, which is expected to serve 200,000 daily riders with three new stations, will cost $4.45 billion. It should open in December, after nine years of construction.

All of which is to say, "more subway" can't be the only answer to dealing with more riders. That's what makes open gangway train cars so appealing: They expand the system's capacity without the labor and expense of expanding the system itself.

We want to look at all options as we move forward with the design of the next generation of subway cars. MTA spokesperson Kevin Ortiz

The design also reduces overcrowding in specific cars or areas, since riders can distribute themselves more easily. London found the design can increase capacity by as much as 10 percent. More than rescuing some poor soul from being lodged in someone's armpit, dispersing passengers can reduce what the MTA calls dwell times, when the train's sitting in a station, waiting for everyone to push their way out of or into particularly crowded cars. There's a potential safety benefit, too, since illegal or dangerous behavior is harder to hide in an open car.

"There are no obvious downsides," transit expert Yonah Freemark wrote on his blog last year. Others have gotten the message: Three-quarters of metro systems outside the US use at least some open gangway cars, Freemark has found. The design's carrying folks around old, established systems in Paris and London, as well as through newer networks in China, Azerbaijan, Algeria, and Egypt.

New York's transit agency isn't making any wholesale changes yet (in case you hadn't guessed, it tends to move slowly). It plans to spend $52.4 million on 10 open gangway cars of two different designs to be used in a single train. The pilot project is part of the authority's 2015-2019 capital plan. The new cars would be ordered early next year, but the MTA hasn't said when they might enter service. They'll be used on the A and F lines, according to The Daily News.

"The idea behind these open gangway cars is that we really want to look at all options as we move forward with the design of the next generation of subway cars," says MTA spokesperson Kevin Ortiz. It's not a change to be made lightly. The lifetimes of these trains are measured in decades, so any design that doesn't work as well as hoped is a very longterm problem.

1Post updated Tuesday, February 2 to clarify the number of trips served by the MTA subway system in 2014.