Abstract:
The project is designed to improve the scour protection of the BNSF Railway Bridge foundations during large discharges of the Prado Dam, which is 1 mile upstream from the project site. The original BNSF Bridge was designed for scour depths of 14 feet in 1995 but due to the Prado Dam being modified to handle larger discharge flows, deeper scour has the potential to occur. The existing railroad bridge includes 3 main system critical tracks that carry 80+ freight and passenger trains daily, which intensifies the project coordination and requires that all work be completer beneath the existing bridge with only 28 to 30 feet of headroom. The new bridge pier foundation protection system consists of reinforced concrete diaphragm walls. The diaphragm walls for the abutments include challenging T Panels designed as cantilever walls due to the proximity to the existing bridge foundations. This requires a specially designed low overhead hydrocutter to perform panel excavation to depths up to 100'.
The Santa Ana River is currently diverted to a channel with water elevations that are above the working platform elevation at times. The project team worked very hard to establish an Emergency Action Plan with all stakeholders to reduce risk for all parties and ensure the safety of its personnel at all times.