Photo by ep_jhu on Flickr.

Before long, the Metro system will be bursting at the seams, besides those spots where trains are already stuffed to the gills. What can we do?

To figure out some solutions, Metro’s planning department has been analyzing many different alternatives for fixing the capacity bottlenecks. They’ve been posting the presentations to their Technical Advisory Group on PlanItMetro, allowing us to get a look at some of the possibilities even before they’re fully analyzed.

To start with, Metro definitely needs to upgrade power systems to accommodate more 8-car trains, and build enough railcars to make up those trains. Other key capacity fixes that have been talked about for years include pedestrian walkways between Farragut North and West, and between Metro Center and Gallery Place.

Even with all of this and the “Yellow and Orange Line Service Increase” plan, trains will have 22% more demand than capacity by 2040, particularly on the Orange Line between Court House and Rosslyn, Yellow between Pentagon and L’Enfant Plaza, and Green between Congress Heights and L’Enfant, especially the segments around Waterfront and Navy Yard.

In the past, we’ve discussed some of the possibilities. One long-discussed option is to separate the Blue Line into a new tunnel of its own through Georgetown, the Mount Vernon Triangle, and H Street.

Left: Possible separate Blue Line. Right: Possible separate Yellow Line.

Click on an image to enlarge.

Another would be to build a separate tunnel for the Yellow Line next to the current Yellow and Green tunnel between L’Enfant and Mt. Vernon Square. This would allow more Yellow and Green trains since ethey would no longer have to share tracks.

However, it would cost a lot of money yet not provide access to any new areas or deal with the growing transit demand as Southwest and Near Southeast become dense residential and job centers. Nor would it do anything about the heavy demand at Union Station, which will only increase as MARC and VRE add capacity.

Another option would be to route the new tunnel through SW and SE, along I Street SW/SE, then turning north past the Capitol to Union Station. Some trains over the bridge could take this route, while others could take the current route. Already, Metro plans to make some of the trains from Franconia-Springfield go over the bridge, so the Franconia trains could be the ones to take the 7th Street route while the Huntington trains went to Union Station, for example:

Click to enlarge.

One drawback of this option is that this new tunnel will not carry the maximum frequency of trains. That’s because there’s a limit to the number of trains through the King Street-Pentagon route, some of which would go to Rosslyn, some to L’Enfant, and the rest in the new tunnel.

The study estimates 6-minute headways during peak and 12-minute off-peak. By comparison, the Red Line has 2.5-minute headways peak and 6-minute off-peak.

In general, this is a drawback of the way the system was originally designed where different lines (except Red) share tracks. Many links don’t get the maximum possible number of trains. To fix that, Metro could separate more lines with new tunnels. Or, they could add more switches so that different routes could use the available capacity:

Click to enlarge.

This option adds four track connections. Three, between Waterfront and the 14th Street bridge, between the bridge and Arlington Cemetery, and between the cemetery and Court House, would enable a new service between Branch Avenue and Dulles Airport.

A fourth lets trains on the Dulles line turn toward Vienna to maximize trains on both of the northern Fairfax branches. New stations connected to West Falls Church and Pentagon for the new lines would also accommodate transfers.

This option gives Virginia a lot more service and the whole system more flexibility to route around problems. On the other hand, it’s likely to lead to more people transferring at more stations, and creates more crowding at Rosslyn since many trains will now bypass it. (Or can Rosslyn get another station like Pentagon does in this option?)

The clear question with all of these is whether Metrorail expansion is even right to consider, or whether money is better spent on light rail and bus service. Dan from BeyondDC always argues that for the cost of one heavy rail line, you can get streetcars and light rail all over the place.

Metro planners also took a look at many of these options, some of which are in the presentation already online while others will come up in future phases of this plan. Stay tuned for more great nuggets of information as the study progresses.

David Alpert is Founder and President of Greater Greater Washington and Executive Director of DC Sustainable Transportation (DCST). He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He lives with his wife and two children in Dupont Circle. Unless otherwise noted, opinions in his GGWash posts are his and not the official views of GGWash or DCST.