The 16-mile light rail line will connect Bethesda to New Carrollton. It's scheduled to open in 2020, but the project is not yet fully funded.
According to the Sierra Club, good transportation projects should "provide an opportunity to further reduce our dependence on oil, reverse climate disruption, and save money."
"Because transportation infrastructure lasts for decades, the impacts of transportation investments are felt for many years to come, with huge consequences for America’s ability to move beyond oil," read the report.
The light rail line has been hotly contested by some advocates of the Capital Crescent Trail, alongside which the rail is slated to run.
Capital Bikeshare, a bikesharing system in Arlington, VA and Washington, DC that's was also ranked amongst the country's best projects.
And the Silver Line, an addition to Metrorail that will connect Falls Church to Dulles Airport, was also named among the best.
Here's what the Sierra Club had to say about the Purple Line:
The D.C. Metro area consistently has among the worst traffic in the nation, contributing to wasted time, increased levels of stress and sub-par air quality. The Purple Line will provide a convenient transportation alternative for those commuting in the D.C. metro area. The Purple Line is a proposed 16-mile light rail through the Maryland inner suburbs of Washington, DC, and links different lines of the heavy rail Metro system. Because the Purple Line is near the core city, it will draw development inward, encouraging revitalization and development where it is most needed. A partial multi-use trail will be completed alongside the Purple Line, providing walking and biking options. The project will be on "grass tracks," reducing storm water runoff and heat gain. The Purple Line is estimated to have 68,000 daily commuters when complete, replacing an enormous amount of automobile traffic, enhancing air quality and decreasing greenhouse gas pollution. The Purple Line is expected to bring in $1.8 billion in revenue, raise property values $8.4 billion and create 27,000 new jobs every year over the course of 30 years according to the Maryland Transit Administration. Construction on this project is scheduled to begin in 2015 and open in 2020.
Do you agree with the Sierra Club? Is the Purple Line among the country's best transportation projects? Tell us in the comments.