Adding stations to the existing Metro system is a plausible way to expand the transit system without some of the costs involved for new routes. The region has a modest track record for infill stations – the NoMa station opened in 2004, and the Potomac Yard station is set to open in 2022.

Both NoMa and Potomac Yard share several characteristics: above-ground tracks passing through formerly industrial areas ripe for redevelopment.

Some criteria for infill station sites:

• Ease of construction: Above-ground locations are the only feasible sites. Lots of planners and crayonistas call out the possibility of below-ground infill subway stations, something that (to my knowledge) has never been done without accommodations for a station from the start.
• Potential surface transportation connections: connecting to arterial streets that can carry connecting bus transit, as well as walkable street networks is vitally important.
• Redevelopment opportunities: these places were bypassed for stations for a reason. Plausible transit-oriented (re)development sites and planning are critical elements.

As it happens, the kinds of places that meet these criteria are often the parts of the network already parallel to existing commuter rail lines. Overlapping services opens the door for additional infill stations on the Metro network.

Let’s imagine a future world where the DC region’s commuter rail systems have been integrated into a coherent regional rail network offering rapid transit service. Even compared to WMATA’s already lengthy suburban routes, those networks extend well beyond the end of the current system. Commuter rail evolves into regional rail; and WMATA (conceived as a hybrid between regional rail and urban rapid transit) evolves further along the rapid transit spectrum.

Based on those criteria, I have twelve possible infill station sites on the existing WMATA network. Many are aspirational, particularly in terms of land use.

Here’s the list:

Location:	State:	Services:
Franconia Road	VA	🔵
Eisenhower Valley	VA	🔵
New Hampshire Ave	DC	🔴
Berwyn	MD	🟢 🟡
Edmonston/Wootton	MD	🔴
Montgomery College	MD	🔴
Gude Drive	MD	🔴
Centerville Road	VA	⚪️
Oklahoma Ave	DC	🔵 🟠 ⚪️
River Terrace	DC	🔵 🟠 ⚪️
Wolf Trap	VA	⚪️
Slaters Lane	VA	🔵 🟡

Some of these sites are opportunistic. That is, the site could support an infill station built at a reasonable cost, even if the land use (both current and future) aren’t likely to change much. Franconia Road is one where adding some platforms to existing track ought to be an easy task (with the caveat that nothing in American transit construction is easy at the moment).

Others are targeted at potential large-scale redevelopment of low-density land uses. And some (e.g. Wolf Trap) are longstanding ideas that might not make much sense, but I’ve included them here anyway.

Take the three criteria above, and score each on a 1-3 scale (with 3 being the best) and this is the back-of-the-envelope ranking:

These twelve additional stations (in addition to the 98 currently open or under construction) have the potential to increase the system’s ridership. Each additional node in the network can increase the value for the network as a whole, particularly given the redevelopment prospects for the region.

Some caveats: Obviously, I’m just spitballing here. The ‘ease of construction’ is all relative, and leaving aside the larger issues of transit construction costs for the time being. Controlling costs will be critical to making any additional infill stations feasible, yet alone stations with marginal scores.

Still, all but one of these locations are above ground, and the one that’s in a tunnel is a short cut and cover segment. There’s precedent for building stations in this way.

I hope to go through the details of each station area in future posts…