Major construction on the Warm Springs Extension in Fremont, CA began in August of 2009 and will continue until the fall of 2015. This project will add 5.4-miles of new track south from the existing Fremont Station to a new station in the Warm Springs District of the City of Fremont.
The Reinforced Earth Company (RECo) was selected to design and supply the four MSE walls for this project that included two technically complex structures.
The two walls supporting Walnut Avenue Bridge are the first RECo MSE walls supporting a true abutment for CALTRANS, the California Department of Transportation. In a true Reinforced Earth abutment, the bridge beams are supported on a spread footing bearing directly on the MSE structure. One of these two walls is also the first MSE wall in the U.S. that is constructed directly above a seismic fault line.
The two abutment walls were designed to accommodate a horizontal seismic acceleration coefficient of 0.75g with a maximum allowable seismic lateral deformation of 2 inches. Due to these extremely high seismic design parameters, both the reinforcing strip lengths and densities are over 2.5 times the norm for a wall of this scale.