Rendering of a potential I-270 monorail.  Image by The High Road Foundation.

As part of plans to widen and add toll lanes to I-270, Maryland transportation officials have promised to consider building a parallel monorail line, as first proposed by private activists. Putting aside whether or not such a line is a good idea, here’s what we know so far about the proposal itself.

An overview of the details is available from advocacy organization The High Road Foundation, and its slick 10-minute video. They describe a 27-mile line from Frederick to Shady Grove, mostly along I-270, with a future second phase extending another seven miles south along MD-355 (Rockville Pike) to downtown Bethesda.

Proposed route for the I-270 monorail. Image by The High Road Foundation.

Frederick to Shady Grove

The northernmost station would be on the outskirts of downtown Frederick, next to the existing MARC station. From there it would make its way to I-270 (the exact path is unclear), where it would then run along the side of the interstate.

In between Frederick and Gaithersburg would be a solid 20-mile-long stretch with only three stops: The Urbana Park and Ride, Comsat (Clarksburg), and Germantown Road. These stations would be up to 8.5 miles apart.

Rendering of potential monorail parallel to I-270. Image by The High Road Foundation.

It’s not clear whether these three stations would be located inside the highway right-of-way, and thus require pedestrian bridges similar to those at highway-adjacent Metro stations, or would deviate off the highway to stop on other properties.

Metropolitan Grove station in Gaithersburg would be about 1/3 mile off of I-270, allowing the monorail to meet up with the Metropolitan Grove MARC and future bus rapid transit (BRT) station. This would be the best place to transfer to MARC trains headed to DC Union Station, and is the site of a long-anticipated transit oriented development that’s on hold until the Corridor Cities Transitway BRT is built.

South of Metropolitan Grove, the monorail would re-join I-270 and then use what looks like I-370 to reach Shady Grove Metro. The initial phase, which the foundation calls a “pilot,” would end there. Riders traveling south of Shady Grove would transfer to the Red Line.

Shady Grove to Bethesda

The potential second phase, south to Bethesda, would follow MD-355 instead of I-270. 355 is the main commercial street parallel to both I-270 and the western leg of Metrorail’s Red Line. The foundation hasn’t indicated where they think all the stations should go in this section, which would closely duplicate the existing Red Line.

Rendering of potential monorail on Rockville Pike near Pike+Rose. Image by The High Road Foundation.

One way the monorail could be different from the Red Line is via station locations. The foundation video includes a rendering of a station at 355 and Rose Avenue (three blocks north of White Flint Metro) that’s integrated into the sixth floor of a future mixed-use high-rise, similarly to the Disney World monorail’s resort stations.

Rendering of potential monorail stop at Rose Avenue, with a stop inside a building. Image by The High Road Foundation.

What does the foundation’s analysis say?

The foundation advocating for monorail appears well-meaning and well-funded. They hired consultants to do conceptual engineering, operations, and ridership analyses for the initial northern phase, and made several reports available to GGWash to read. According to their advocacy materials, the Frederick-to-Shady Grove monorail would:

  • Fit completely into existing rights-of-way (although it’s unclear if this includes all stations).
  • Come every three to 15 minutes, depending on time of day.
  • Travel at up to 70 miles per hour, taking 31 minutes to move from Frederick to Shady Grove.
  • Carry between 39,000 and 55,000 passenger trips per day by 2045 (depending on operating characteristics and differences between forecasting methods).
  • Cost about $3.4 billion total, or $127 million per mile.
  • Be fully automated and thus cover all of its operating costs, not requiring any ongoing subsidy from the government.

Some of these claims appear pretty solid. For example, the ridership forecast was generated by a consultant that also generates them for the government, using substantially the same process. 39,000 to 55,000 is a big range, but it’s probably similar to what a government report would come up with, at least preliminarily.

On the other hand, some of these claims appear tinted with rose-colored glasses. Metrorail was supposed to be automated too.

What comes next?

In terms of planning work, the High Road Foundation has done as much or more as any advocacy organization could do. At some point, the state has to take over.

In June, the Maryland Board of Public Works voted to require the Maryland Department of Transportation (MDOT) to study the monorail as an option while developing plans for toll lanes on I-270. Exactly how seriously MDOT will take the monorail — or transit in general — remains to be seen.

In theory, states are supposed to study several different modes before deciding on one for a big project like this. MDOT did such a study in the early 2000s, which resulted in the recommendation to build the Corridor Cities Transitway BRT.

But that early 2000s study focused its transit recommendations on goals in Gaithersburg and Germantown. Different goals, like trying to connect to Frederick, might yield different results.

Corridor Cities Transitway BRT map.  Image by State of Maryland.

A serious study would consider several different alternatives, not only mode but also route. Would improving the existing MARC line make more sense? What about BRT using the I-270 toll lanes that Rahn’s study is sure to recommend regardless? What about other types of trains like DMUs, either on existing tracks or new ones somewhere?

Presupposing a mode and route isn’t how real mass transit planning happens. If the state puts serious time and money into looking at a broad array of mode and route choices, that’s a serious outcome, though a frustrating one given that MDOT already went through it in the early 2000s. On the other hand, if the state tosses a chapter about monorail into a study that exists to make the case for toll lanes, and uses that chapter to say they’ve considered and rejected transit, then that’s not a good-faith look.

In a future post, GGWash will look whether monorail’s particular strengths and weaknesses actually do or do not lend themselves to the I-270 corridor.