Maryland’s Purple Line is on the verge of collapse, and if the project dies, a rare well-designed light rail system dies with it. Project delays, cost overruns, and disgruntled contractors are nothing unusual to public rail projects—but the Purple Line’s design sets it above the rest.

The Purple Line has existed in various ideas and concepts for several decades, going back to 1987 when Maryland began acquiring the right-of-way from railroad company CSX for passenger rail use. It was not until 2008, when then-governor O’Malley announced the creation of a light rail system 16 miles long with a price tag of over $2 billion.

The Purple Line distinguishes itself from the rest of the D.C. Metro system it integrates into in a few ways, which are what earn it the term light rail. Light rail is typically slower than metro (or heavy) rail, with fewer cars. But its exclusive right of way and number of cars make it more efficient than its bus counterparts.

The problem with most light rail systems comes down to what they are used for. It may sound strange, but many light rail systems are not designed with transportation as a first priority. Instead, governing bodies use light rail, often in street-car or tram form, as an economic development attraction. To use an example just a few miles from the proposed Purple Line, consider the DC Streetcar. It runs slowly because it is at grade and subject to traffic. There are potential plans for expansion, but at its current 1.9 mile stretch, it doesn’t have the network it needs to compete with other modes of transportation. Although some will argue that the DC Streetcar is performing above expectations, it does not match the rider-per-mile level of its X2 bus counterpart, which is cheaper to operate and more flexible to growth.

The point here is twofold: ridership over economic development and providing a viable service network that can reasonably entice people away from less efficient forms of transportation are important, and that is where the Purple Line succeeds. The 21 stations along the Purple Line are not in glamorous areas or tourist hotspots. Instead, the line runs through the Maryland suburbs. More importantly, the route has a purpose; to connect those suburbs to a larger transportation network.

The Purple Line connects the eastern ends of the orange, green, and yellow lines, along with both spurs of the red line. In addition, it connects to MARC and Amtrak services. This connectivity increases the likelihood of ridership, according to standard transportation theory. To understand why, it’s important to take a broader look at how transportation decisions are made.

Four Step Model

When modeling transportation, there are four primary considerations: trip origin, trip destination, mode choice, and route choice. New transit will compete against all other options in each of these categories, so they all must be considered when designing a new route.

The Purple Line’s location in the suburbs means that trip origins are more likely to begin in transit. Easy and accessible systems located in population clusters attract users, and the shorter the distance a user must walk to use transit, the higher the likelihood of its use. 

Trip destinations take into consideration how accessible the destination is from the point of origin, e.g. a trip from home to work. Mode choice includes cars, light rail, bus, cycling, walking, metro systems, and more, and can include a mix of modes. Route choice is what addresses connectivity. It can be described as a series of links between the trip’s origin and destination.

The traveler will, based on those four factors, determine his or her best route. If the bus takes 45 minutes to come, is often late, and will take an additional 45 minutes to reach destination whereas taking a car will take 20 minutes and there is guaranteed parking, very few people will choose the bus when the car is an option.

Any point of friction that makes a mode harder to use decreases ridership. Any step to reduce friction increases ridership. This is ultimately where the Purple Line excels. It provides a route along the beltway that will travel at a consistent speed, connect riders to D.C. and Virginia by way of the Metro, or to Baltimore and elsewhere by way of Amtrak and the MARC train. 

The light rail will not be subject to traffic delays like the bus lines it will compete with and that currently serve as the connectivity links in the transit network, and it will be running more frequently. Both have major impacts on the demand that light rail will receive. 

The Purple Line will also not be subject to the traffic along the beltway, which automobile users are exposed to, unless they opt for costly express passes. Exuberant parking fees in central D.C. can also be avoided, and the suburb-to-suburb line fills a gap that Uber or personal automobiles have dominated in the past.

The Future of the Line

None of this is to say that the Purple Line should go without criticism, or that it is a perfect model for the future of light rail. The cost of the 16-mile project is still massive. The costs of U.S. rail infrastructure in general have ballooned compared to its European counterparts.

The Purple Line was created through a public-private partnership which has all-but-dissolved and been widely considered a failure. Its execution has been poor at best, with the project running into all of the problems now seemingly guaranteed in a new rail project.

Despite those challenges, the Purple Line exists as an example of what light rail could be. Not a shiny economic development tool—the next streetcar to become an example of government excess—but instead a link that offers choice to travelers. 

The Purple Line stands out because it does not try to. It becomes simply another line in the D.C. Metro system. But if that line is more convenient for a significant number of riders than the already existing network, it’s a Purple Line worth building.

Ethan A. Greene is the Planning Director of a small Mississippi town, holds a masters of city and regional planning from Clemson University, and is a former D.C. resident and daily rider of the Metro. This New Urbanism series is supported by the Richard H. Driehaus Foundation. Follow New Urbs on Twitter for a feed dedicated to TAC’s coverage of cities, urbanism, and place.