Last week, Maryland governor Larry Hogan announced the state will not move forward with the Baltimore Red Line. He argued building it would be too expensive, particularly the tunnel that would have run through downtown. Was the tunnel necessary?

A part of what Baltimore’s transit map could look like with the Red Line. Image by Peter Dovak.

The proposed Red Line would have been a light rail line from the Center for Medicare and Medicaid Services west of Baltimore through West Baltimore, the Inner Harbor, the growing Fell’s Point and Canton areas, to Johns Hopkins’ Bayview campus.

It would have connected MARC commuter rail stations on both sides of the city, the existing light rail, and the city’s Metro line. There would have been two segments in tunnels: a short one under Cooks Lane near the county line and a longer, four-mile one under downtown.

Following the cancellation, a common question is whether the line still happen without the tunnels. Building a tunnel preserves a lot of roadway for cars, but what if Maryland didn’t worry about impacts to drivers and dedicated road lanes for the Red Line’s exclusive use?

Unfortunately, running the Red Line on the surface, even if nobody minded inconveniencing drivers, wouldn’t work as well as one might imagine.

Portion of the Red Line route map. The dashed line denotes the tunnel.

Where the blocks are small, dedicated lanes have limits

Pratt and Lombard Streets in downtown Baltimore are each four-lane, one-way streets. The Purple Line will take two of University Boulevard’s six lanes in Langley Park. What’s the difference?

The difference is intersection spacing. Without a tunnel, a light rail line still will have to stop at many intersections for cross traffic.

In Downtown Baltimore, intersections are extremely closely spaced, and virtually all of them are signal controlled as part of the grid of street lights. On University Boulevard in Langley Park, the superblock rules, and many streets that intersect do not cross the median. That allows much more flexibility in the design of the Purple Line, and means the train isn’t stopping every 600 feet, even if it is stopping at every light (which, hopefully it won’t be).

Additionally, it’s much easier to synchronize signals for transit in a suburban environment, where most of the volume is on one street (like University). In a central city, the demand is spread out much more evenly and there’s no peak demand direction. Everyone is going every which way.

It’s very difficult to pre-empt signals for transit without causing gridlock nearby. This is essentially the reason the current Baltimore Light Rail line doesn’t have that feature. And without it, the line is painfully slow in the central city.

In announcing why he was canceling the Red Line, Hogan criticized Baltimore’s current light rail system as being among the least popular in the country. In part, that’s because it bypassed major jobs an population centers in an effort to make the line cheaper to build. It’s also because downtown, the line is slower than molasses on a cold day because it runs in a transit mall and does not have transit signal priority.

Some streets are narrow

Other streets along the Red Line corridor aren’t wide enough to dedicate lanes to transit, like Fleet Street in Fell’s Point, which is just one lane each way plus parking.

Ben Ross explained why there couldn’t be a shorter tunnel segment:

The tunnel goes through downtown at a track elevation of approximately 80 feet below sea level in order to bore through competent bedrock and avoid the cost and disruption of cut-and-cover construction and the need to relocate utilities under a street whose width wouldn’t leave much room for them (Lombard Street). This requires a substantial length of tunnel to slope down to the final depth. Then there is a substantial portal zone where the tracks slope down but the top of the train is still above street level. This needs to be located where the blockage of cross traffic by vehicles and pedestrians will not be a major problem. Both of these factors push you to move the tunnel entrance away from downtown.

It’s important for the line to go through these older neighborhoods with narrow streets because a lot of potential riders live or work there.

It’s easier for the Purple Line

Between Bethesda and Silver Spring, the line is essentially grade separated now. There’s only one crossing in the stretch (at least in the most recent proposal; we have no idea what the governor has cut), so trains won’t have to fight their way through traffic.

In Baltimore, where there’s no easy right-of-way to use for the Red Line, the subway was the only way to give trains a quick way through downtown. That wasn’t a “fatal flaw,” as Governor Hogan put it, it was one of the best features of the line.

The Red Line’s Alternative Analysis showed that a surface alignment for the Red Line would require 13 minutes for trains to cross downtown. With the tunnel, trains would be able to cover the distance in just five minutes.

Other transit systems do the same

The most successful light rail systems in the country all have grade-separated sections in their downtowns. They include systems in Charlotte, Cleveland, Los Angeles, Philadelphia, Pittsburgh, San Francisco, Seattle, and St. Louis.

The Red Line needs to have a tunnel through downtown, and honestly, so does the north-south light rail line. It could be possible, if a new tunnel for CSX is constructed, to convert the Howard Street Tunnel into a light rail subway (as Saint Louis did). Or perhaps a new subway alignment for the north-south line could be built in a parallel corridor.

It’s worth looking at costs on a project like the Red Line, but the teams that considered alternatives and chose this one did in fact study the costs and benefits of a tunnel. They had good reasons to choose what they did.