Abstract:
Many cities in the United States have identified and used existing railroad corridors or wide roads for new light rail alignments. But there is a finite number of these corridors, and the expansion of light rail service will require the insertion of light rail into developed communities. The Purple Line light rail project is notable because it is planned for a developed corridor in older inner- ring suburbs. The corridor is characterized by narrow curvilinear roads and a landscape of rolling hills and steep stream valleys. As a circumferential route crossing many of the major radial routes that lead to the center of Washington, D.C., there are few obvious large arterial roads that could accommodate the addition of a light rail line. This paper demonstrates some of the creative solutions specific to local conditions used on the Purple Line. Inserting light rail into this environment requires ingenuity and full use of the operational flexibility of light rail as a mode. Different conditions in the corridor have been addressed with a range of design responses. This paper will describe some of the challenges faced by Maryland Transit Administration’s (MTA’s) planners and engineers and what design solutions have been proposed. There will also be a discussion of some of the tradeoffs to operations, travel times, or community impacts that were evaluated.
