Purple Line Preliminary Engineering – Design Build Package

Location

Montgomery and Prince George’s County, MD

Status

Under Construction​

Client

Maryland Transit Administration

Cost

$3.2 Billion​

The Purple Line is a critical light-rail link for the region, integrating the existing radial Metro system with the first circumferential transit, connecting Metrorail and Bus at Bethesda, Silver Spring, College Park, and New Carrollton in addition to new transit access at 17 other stations.

As Concept Designer for all the facilities, KGP created underground, at grade and aerial stations as well as bridges, bicycle trails and a unique station planned into the new Silver Spring Library. The train passes through a new public plaza under the library where a major downtown station is located.  During the PE phase KGP was the Design Architect for ten stations including Silver Spring Intermodal Station and a number of other structures like the Rock Creek train and trail bridge.

Silver Spring is the busiest and most complex station in the system, connecting Metro, MARC, Amtrak, local bus services and the regional bicycle trail system.  The station is located approximately 80 feet above the WMATA Red Line entrance, between the existing elevated Metro and MARC stations and the adjacent Bus Transit Center.  There are four levels linking circulation elements to all three transit platforms plus horizontal connections to the Capital Crescent Trail, the Bus Transit Center and a potential new WMATA mezzanine.

The SSTC is distinguished by a long enveloping canopy structure, which addresses the functional and environmental challenges faced when building an aerial station with high exposure to winter winds.  KGP responded with clear span arched rib structure running at 9’ intervals with a secondary set of diagonal arched rectangular tube ribs providing lateral support.  The canopy is clad in a mixture of solid metal, perforated metal, and glass panel skin.

The underground station at Bethesda is connected down 100 feet to Metro with four high-speed elevators.  The PL Station is just below the surface which allows patrons to enter from a new public plaza as well as stairs and elevators.

Other structures for the project include bridges such as the Rock Creek Bridge which falls under the National Capitol Planning Commission.  The trail needed to cross the tracks and this location provided the opportunity to combine the crossing into a single bridge structure.