Light RailMetro
Can operate easily along commuter streets and be crossed by pedestrians and automobiles Must operate in exclusive right-of-way separate from pedestrian and street traffic
Powered by overhead contact system (OCS)  Powered by 3rd rail
 Modular train (all 1 piece) – 140 feet  Multiple car train (between 6 and 8 cars) – 75 feet per car

A traction power substation (TPSS) is an electrical substation that converts the electric power from the utility company (PEPCO) to the proper electrical voltage (1500 Volts DC) and frequency needed for the operation of the Purple Line trains.

The TPSS will be housed in a steel building similar in size to a car garage, 58 feet by 18 feet and will be fed by underground electrical feeds. It is similar in function to the transformer mounted on utility poles and supplies the power to the catenary wires of the light rail. There is a total of 10 TPSS along the Purple Line alignment; located approximately every two miles. The graphic below depicts a typical TPSS in comparison with the Purple Line light rail vehicle.


The Purple Line project includes the completion of the Capital Crescent Trail (CCT) between Bethesda and Silver Spring, the completion of the Green Trail along Wayne Avenue to Sligo Creek, and the construction of a bike path through the University of Maryland campus. Each of the hiker/bikers paths as well as community connection to the Capital Crescent Trail are detailed below. For more information about Biking along the Purple Line, please see our Biking with the Purple Line handout.

Capital Crescent Trail

  • The interim trail built in the former Georgetown Branch railroad right-of-way which currently extends between Bethesda and Stewart Avenue in Lyttonsville will be replaced by a 12-foot paved trail with 2-foot buffers that extends all the way into downtown Silver Spring.
  • The trail will be paved and landscaped with new formal access points from local neighborhoods.
  • The completed trail will include trail bridges over Connecticut Avenue and Colesville Road, and underpasses at Jones Mill Road, 16th Street, and Spring Street; making a safer trail for the public.
  • The completion of the trail into downtown Silver Spring will be a major enhancement of the local trail network, linking the Capital Crescent Trail, the Metropolitan Branch Trail and the Green Trail.

Silver Spring Green Trail

  • The Silver Spring Green Trail along Wayne Avenue will be completed between Sligo Creek Trail and Fenton Street.
  • This multi-use urban trail will connect with the Capital Crescent Trail and the Metropolitan Branch Trail within the Silver Spring Transit Center property.
  • The trail will be an 8- foot wide paved path with 2 foot shoulders along with lighting in the area of trail connections and landscaping.

University of Maryland Campus Bike Path

  • A new bike path will be built along the Purple Line route through the campus of the University of Maryland.
  • This path will provide better and safer facilities for the large number of cyclists and pedestrians on campus, encouraging this environmentally-friendly transportation.

Project Milestones


  • Reliable and rapid east-west travel
  • Connects to Metrorail Green and Orange lines and both branches of the Red Line
  • Supports community revitalization and transit-oriented development
  • Provides an environmentally friendly transportation option to help reduce auto-dependent travel
  • Connects people to jobs
  • Improves connectivity to the regional Metrorail system
  • Connects to commuter rails MARC, Amtrak, Metro and local and regional bus routes
  • Completes the Capital Crescent Trail between Bethesda and Silver Spring, the Green Trail along Wayne Avenue to Sligo Creek trail, and a bike path through the University of Maryland Campus


  • 16.2 miles
  • 1 short tunnel (Wayne Avenue to Long Branch)
  • 21 stations
  • 5 modular light rail vehicles spanning 140 feet per train
  • Comfortable, well-lit interiors
  • Quiet operations
  • Low floor for easy boarding
  • No fare gates at stations for faster access
  • On-board storage for bicycles
  • ADA compliant

Environmental Benefits

  • The Purple Line is estimated to take 17,000 cars off of the road daily, saving 1 million gallons of gas within 20 years.
  • Electric power means no air emissions into the immediate environment
  • Purple Line’s use of existing roadways minimizes effects on land and water resources

Community-Friendly Light Rail Transit

Light rail vehicles are modern streetcars, powered by overhead electrical wires.
Features include:

  • Low floors to allow passengers to board without climbing steps
  • Quiet operations
  • Neighborhood stations convenient for pedestrians and bicyclists

Purple Line light rail vehicles have been designed with special wheel profiles, noise dampening wheel skirts, and other noise reducing measures to ensure the train will not exceed 75 decibels on straightaways and 78 decibels on sharp turns.

The MTA prepared additional analyses of a number of topics. The results of these studies can be accessed below:

Prior to the construction of the Georgetown Branch Interim Trail, Montgomery County sought an administrative determination from the Federal Transit Administration on whether the creation of an interim trail would cause the Georgetown Branch right-of-way to be considered parkland under a federal law known as Section 4(f). The correspondence can be read below.