One of the engineering feats of its day, the Loop was built by Southern Pacific Railroad to ease the grade over Tehachapi Pass. Construction began in 1874, and the line opened in 1876. Contributors to the project's construction include Arthur De Wint Foote and the project's chief engineer, William Hood. The siding on the loop is known as Walong after Southern Pacific District Roadmaster W. A. Long. The project was constructed under the leadership of Southern Pacific's civil engineers, James R. Strobridge and William Hood, using a predominantly Chinese labor force. The Tehachapi took under two years to complete, featuring 18 tunnels, 10 bridges, and numerous water towers for the steam locomotives. Between 1875-76 about 3,000 Chinese workers equipped with little more than hand tools, picks, shovels, horse-drawn carts and blasting powdercut through solid and decomposed granite to create the helix-shaped 0.73 mile loop with grades averaging about 2.2 percent and an elevation gain of 77 feet. In 1882 the line was extended through Southern California and the Mojave Desert with 8,000 Chinese men working under Strobridge and another man. Both of the men came out of retirement after working on the Central Pacific Railroad. A large white cross, "The Cross at the Loop", stands atop the hill in the center of the loop in memory of two Southern Pacific Railroad employees killed on May 12, 1989, in a train derailment in San Bernardino, California. The Tehachapi Depot Museum stands in the nearby town of Tehachapi.
Operations
The Loop became the property of the Union Pacific in 1996, when the Union Pacific and Southern Pacific systems merged. Trains of the BNSF Railway also use the loop under trackage rights. Although Southern Pacific ran passenger trains on the Loop for years, it banned passenger service there soon after handing its trains to Amtrak in 1971. Union Pacific has maintained the ban since taking over Southern Pacific. As a result, Amtrak's San Joaquin train is unable to directly serve Los Angeles. Amtrak operates Thruway Motorcoach buses for passengers wanting to travel between the Central Valley and Los Angeles. An exception is made for the Coast Starlight, which uses the line as a detour if its normal route is closed.