. The railway line along
Alameda Street was originally laid out by Los Angeles' foundational
Los Angeles & San Pedro Railroad, which opened to traffic in 1869. The railroad would go on to be acquired by the
Southern Pacific Railroad in 1873, becoming their San Pedro Branch. A 1984 study by the Ports Advisory Committee recommended the San Pedro Branch be upgraded to meet the growing demands of the ports of Long Beach and Los Angeles. These rail lines were inadequately protected with little more than
"wigwag" crossing signals dating from the original construction of the lines. In response, the Alameda Corridor Transportation Authority was established in August 1989 to plan for upgrades along the route. By the early 1990s, the Southern Pacific was in a difficult financial position and sold the Alameda Street corridor to the Ports of Long Beach for in December 1994 ($ in adjusted for inflation). This allowed the ACTA to begin building a freight rail "expressway" from the ports to the major rail yards near Downtown Los Angeles. The centerpiece of the new Alameda Corridor would be the "Mid-Corridor Trench," a below-ground, triple-tracked rail line that is long, deep, and wide, with a
track spacing of . The trench and the larger Alameda Corridor would allow freight trains to travel without concerns about grade-crossing collisions or having to blow their horns as they traveled through neighborhoods. The corridor would be open to both
BNSF Railway and
Union Pacific Railroad (UP) trains via
trackage rights. Trains have become much longer since: in 2006, the line carried 19,924 trains carrying 4.9 million
twenty-foot equivalent units (TEUs) of containers, while in 2021, only 10,928 trains carried the same 4.9 million TEUs. Fifteen percent of the nation’s container traffic travels through the corridor according to the Transit Authority. While the Mid-Corridor trench is the spine of the corridor, the Alameda Corridor Transit Authority also maintains more than of freight rail track, with 125 turnouts, ten rail bridges, signals at 48 locations, seven grade crossings, and two stormwater pump stations. In 2024, the
Alameda Belt Line (using the name and charter of
a former line in Northern California) took over dispatching as a neutral third party. It is a jointly owned subsidiary of BNSF and UP. ==Additional developments==