Sean Emerson is a Strong Towns member and resident of Silver Spring, MD. Today he's sharing a response to an article recently posted on our site, "A Purple Line Alternative" with his own take on a proposed rail line in the Washington, D.C. metro area and why he feels it is a project created in accordance with Strong Towns principles.

We welcome these sorts of debates on our site. If you have an opinion to share on an issue related to Strong Towns, send it our way.


On Tuesday, Strong Towns published a guest piece by a D.C. area resident who believes that the Maryland Purple Line light rail project is not in accordance with Strong Towns principles.  As a member of Strong Towns and supporter of the Purple Line project, I disagree with that position.  I find the Purple Line to be the outcome of the incremental progression of the communities that it will soon serve. 

I find the Purple Line to be the outcome of the incremental progression of the communities that it will soon serve.

The Maryland Purple Line will be a 16-mile light rail transit line connecting Montgomery and Prince George’s counties just outside of the nation’s capital, running in a dedicated right-of-way for almost the entire route to bypass traffic congestion.  The line, projected to cost $2 billion dollars, will connect the Washington Metro lines serving Montgomery and Prince George’s counties, and it will bring rail transit to a corridor largely made up of financially-productive land use patterns that has evolved over the past century.  

Tuesday’s piece posited that the Purple Line as a light rail line is excessive, and that expanding limited-stop bus service in the corridor would represent a more incremental progression of transit service than making the leap to light rail.  I, and the numerous supporters of the Purple Line project, find that the corridor to be served by the line has already incrementally progressed past the phase of bus service and is worthy of a light rail connection.    

This is not to say that bus rapid transit (BRT) as a mode is less preferable to rail in every scenario.  My neighbors and I in the eastern portion of Montgomery County, Maryland are currently advocating for a proposed BRT line on U.S. Route 29, a major thoroughfare traversing a corridor filled with tens of thousands of apartments, single family homes, and numerous large employment and retail destinations.  On the U.S. 29 corridor, we are supporting BRT rather than aiming for light rail or a Metrorail line because we recognize that BRT is the next appropriate level of transit improvement over the crowded and often congestion-delayed local bus service that presently serves the corridor.  

Source: PurpleLineMD.com

Source: PurpleLineMD.com

The Purple Line corridor, on the other hand, is unique.  While a suburban area by definition due to its proximity to D.C., the Purple Line corridor is composed of communities that are large enough to be considered cities in their own right.  

The corridor consists of downtown Bethesda and downtown Silver Spring, two regional centers with dozens of high-rise office and residential buildings in a productive urban land use pattern.  Farther east, the corridor includes the immigrant communities of Long Branch and Langley Park, home to thousands of apartments and hundreds of businesses.  The bus routes serving these communities are amongst the busiest in the D.C. region and the state of Maryland, some averaging over 10,000 daily riders despite unpredictable service and traffic delays.  

The Purple Line route then passes through the University of Maryland-College Park, the state’s flagship university home to tens of thousands of students, most of whom commute to campus for class.  The line then continues through the community of Riverdale, another community with significant productive land uses and transit patronage, before terminating at the New Carrollton Metro and Amtrak/MARC commuter rail station.  

Simply put, the Purple Line should be built as rail rather than BRT because it is one of the few corridors in the country that warrants light rail.  Aside from the existing productivity of the corridor, there are numerous large scale development projects in the pipeline for areas surrounding Purple Line stations.  Unlike other rail transit lines built out into undeveloped areas (with substantial federal funds and minimal local funds) in hopes of spurring some kind of economic development, the Purple Line goes through existing productive areas and has real investment waiting for the green light.    

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Furthermore, constructing a high quality busway with two dedicated lanes that would offer similar time-savings to the Purple Line would require a similar large-scale infrastructure project because many of the arterial roads along and parallel to the Purple Line’s route do not have the right-of-way width to accommodate a dedicated transitway without major construction.  The bus routes that currently traverse these roads are frequently bogged-down in serious traffic congestion, including the limited-stop Metrobus Route J4, which was funded by the state to serve part of the future Purple Line corridor until the line is constructed.  

Roads like East-West Highway (MD-410) and Piney Branch Road (MD-320) simply don’t have the space to add a transitway without significant right-of-way acquisition and roadway reconstruction costs.  While it would be nice to try a high-quality busway before investing in light rail, the costs to achieve that level of quality are exceedingly high due to the constrained right-of-way of roads in the corridor.

Additionally, even a high quality busway would need far more personnel and vehicles than a light rail line to accommodate the projected ridership of the Purple Line.  The Purple Line is projected to carry up to 70,000 passengers per day in 2040, and while the numbers have been a source of intense debate, even drastically lower ridership numbers could only be accommodated with dozens of bus drivers and vehicles.  For example, New York City’s Select Bus Service route Bx12 carries over 50,000 people per day across the the Bronx, but it requires three minute headways 18 hours a day in dedicated lanes to accommodate that level of ridership.  

As a light rail line, the Purple Line’s 136’ open-gangway trains will have far greater capacity than a 60’ BRT vehicle, requiring far less personnel to achieve the same amount of person throughput.  Even if the Purple Line’s ridership projections don’t materialize, a BRT system would require significant resources and infrastructure to accommodate even half of the Purple Line’s projected ridership.       

While it is prudent to be leery of “shovel ready projects” that have been selected by local governments for construction but not funded during normal appropriation cycles due to a lack of return, the Purple Line does not fall into that category.  The Purple Line is an investment-ready corridor, and the state and county governments have invested hundreds of millions of dollars themselves.  The line is projected to generate $12.8 billion in increased property values on land surrounding stations.  Unlike many projects funded through the TIGER program in the past several years that have murky tangible returns on investment at best, the Purple Line has a clear tangible return on investment that greatly exceeds the cost of the project.      

The Purple Line not only survived the trials of uncertainty, but it got stronger over time, gaining more and more support over the years despite serious setbacks and opposition.

No project is perfect, and every project should be viewed with a healthy dose of skepticism before it is funded for construction.  30 years of planning does not make a project worthwhile, but surviving uncertainty does.  As described by Nassim Taleb, uncertainty is key to fostering antifragility in any system.  Things need to be exposed to stressors, repeatedly; otherwise they become fragile (or risk having their inherent fragility exposed).  

The Purple Line idea didn’t sit on a shelf for 30 years waiting for a federal grant to come along and make it a reality.  It was fought for continuously over three decades by civic activists, elected leaders, and the business community.  The project was nearly killed multiple times, surviving governors of opposing political parties, proposed mode changes, and numerous lawsuits.  

The level of scrutiny applied to the Purple Line is perhaps unprecedented for any major transportation project in the country.  The Purple Line not only survived the trials of uncertainty, but it got stronger over time, gaining more and more support over the years despite serious setbacks and opposition.  The original narrow support for the project by a handful of civic activists eventually grew into a broad community coalition consisting of dozens of regional organizations supporting the project from across all spectrums of civic life.   

While there are plenty of examples of projects across the country that find their way to construction despite minimal identifiable return on investment and questionable merits, the Purple Line is not one of those projects. The Maryland Purple Line is an antifragile project that is in accordance with Strong Towns principles.

(Top photo source: PurpleLineMD.com)


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About the Author

Sean Emerson has been a Strong Towns member since early 2015, when he first learned about Strong Towns after stumbling upon a video of Chuck Marohn's Curbside Chat.  He lives in Silver Spring, Maryland, where he blogs about his community at Around The Corners.  He serves on the board of Action Committee for Transit, a transit advocacy organization in Montgomery County, Maryland.  He strives to make his community a stronger town, taking the "Keep doing what you can do build Strong Towns" message to heart.