I-270 at Watkins Mill Road Interchange
Award of Merit
OWNER: Maryland Dept. of Transportation State Highway
LEAD DESIGN FIRMS: KCI Technologies Inc. and Gannett Fleming
GENERAL CONTRACTOR: Wagman Heavy Civil Inc.
CIVIL ENGINEER: Whitman, Requardt & Associates LLP (Bridge)
OWNERS REP AND STEAM SPECIALIST: Greenman-Pedersen Inc.
SUBCONTRACTORS: WF Wilson & Sons (Utility Relocation); Pleasants Paving; Interlock Steelworkers (Rebar Installation); Stolar Construction (Electrical, Lighting Signals); Bulldog Distribution LLC (Trucking and Aggregates)
Constructed over three years, the $110-million crossing helps reconnect long-separated communities. The bridge incorporates a shared-use path for cyclists and pedestrians and fosters a sense of transition through the use of an ashlar stone form liner finish on all precast and cast-in-place concrete elements to match adjacent neighborhood retaining walls.
The project also used brown coatings for bridge beams, light poles, sign structures and guardrails, blending into I-270’s existing color schemes. Utility relocations included a 48-in. water line, two 16-in. sewer lines and a critical electrical duct bank, all of which were located within an environmentally sensitive floodplain. A temporary access bridge and 500-ft stream relocation supported critical elements early in the schedule, improved constructibility and minimized traffic disruptions. Unusual drainage design elements were used to fit within the project constraints. Jack-and-bore techniques allowed a 30-in. pipe to be installed beneath the highway without the need for traffic closures. The project team simplified construction of various project elements.
A 10,000-sq-ft retaining wall, which originally was planned to be built directly in front of and adjacent to an existing 20-ft-high mechanically stabilized earth wall, was revised into a less disruptive permanent top-down tieback wall. Excavation for another retaining wall located alongside an on ramp risked undermining foundations for two high-voltage electrical towers.