As part of the Design-Builder’s team, Schnabel worked with Parsons Transportation Group to monitor over 2,500 geotechnical instruments installed on historical iconic buildings, third-party facilities and along the busy streets of Los Angeles. Schnabel evaluated and interpreted all the instrumentation data in real-time. This information was important to both the Design-Builder and Owner to meet the project goals of advancing the work safely and expeditiously, while simultaneously protecting existing structures and managing stakeholder concerns regarding the perceived risks of construction.

Los Angeles Metro’s Purple Line Extension Transit Project – Section 1 is the first of three sections being built along a new 9.1-mile corridor below Wilshire Blvd. The project, scheduled to be in operation in 2023, includes twin subway tunnels extending from the existing Purple Line to three new stations along Wilshire at La Brea, Fairfax, and La Cienega. The station shafts are approximately 1000-ft long by 70-ft wide and between 65- to 80-ft deep. Between the stations, twin Earth Pressure Balance Tunnel Boring Machines were employed to mine the tunnels in the San Pedro formation (dense sands to silty sands interbedded with layers silts and clays) and the Fernando formation (weakly cemented siltstone/claystone). Among the more notable challenges posed by the ground were significant deposits of tar-sands, which led to unusual material behavior and the presence of hazardous gas.