City: Washington, D.C. (suburbs)
Future Owner: Virginia Department of Transportation
General Contractor: Flour Lane Construction
Schnabel was hired to design and install permanent walls along a fourteen mile stretch of the I-495 as part of a public/private partnership (P3) to widen the highway and reduce congestion. Schnabel constructed seven tieback walls, twenty two cantilever walls, and one secant pile wall. Seventeen of the walls also had sound barriers above the retaining walls.
The walls were constructed by installing galvanized piles into pre-drilled holes and back-filling the holes with concrete. Timber lagging was then placed between the piles to retain the earth as the walls were excavated. Precast panels were placed in front of the lagging as a permanent facing. Placement of the precast panels was done by both Schnabel and other Contractors.