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.