The centerpiece of the Alameda Corridor is the Mid-Corridor Trench, which is 10 miles long, 33 feet deep and 51 feet wide. Traveling north from the Ports, cargo-laden trains descend into the trench north of State Route 91 in Compton and emerge at 25th Street near the border of Vernon and Los Angeles. Not only does it link the North and South Ends of the Corridor, but it also includes most of the new signalized trackwork throughout the entire Corridor. The Mid-Corridor Trench represents about two-thirds of the expenditures of the Alameda Corridor. The 10-mile long trench contains three mainlines with a total of 30-miles of track to handle long-term growth in cargo volumes to and from the Port complexes of Los Angeles and Long Beach.
The 10-mile-long trench follows Alameda Street through six independent Cities and provides improved aesthetics, noise mitigation and traffic flow. Bridges carry vehicles over the Mid-Corridor Trench at 30 east-west crossings, completely separating rail traffic from street traffic and significantly reducing congestion. The trench walls consist of 3′ diameter piles, braced at the bottom by a concrete slab and at the top by precast concrete struts. Over 1 million cubic yards of concrete and 75,000 tons of reinforcing steel were used, and 400,000 tons of ballast were placed to support the tracks. Nearly twenty miles of adjacent roadway were also reconstructed and the signals synchronized to further improve traffic flow. Nearly 60 miles of tracks were constructed throughout the Corridor, 30 miles of which are in the Trench.
Project details can be found below. A map depicting this project can also be viewed here.