Operations Across Tehachapi Pass
From the earliest days of steam locomotive operations, the Tehachapi Pass was a helper district, with eastbound helper added to the rear of trains at the Bakersfield yard and removed at summit, and in some cases, westbound helpers added in Mojave and removed at Summit. When Santa Fe began running trains, it too used rear-end helpers from Bakersfield east. (what about Mojave west???) Helpers locomotives removed from the trains returned to their originating points as (groups of) light engines.
Large steam locomotives were always part of the Tehachapi locomotive scene, with SP using 4-8-0s from 1882, and even its early 4-10-0 between 1885 and 1892, both in head-end and helper service. To facilitate the use of the largest locomotives over the pass, locomotives used south of Bakersfield (railroad “east”) were often different from those used north of that location. From 1917, SP 2-10-2s operated on Tehachapi, in both freight and passenger service. It was also not uncommon to find 2-8-2s on passenger trains over the Tehachapis, although normal passenger power was 4-6-2s.
From the mid 1920s, 4-8-2s began to appear on passenger trains, and in 1928, 4-8-8-2 cab-forwards began to appear on freights and the 20102 were moved away. By this time, Santa Fe was using strings of up to five of its 2-10-2s on freight trains over the pass. In the early 1940s, Santa Fe trains across the pass started to be diesel-hauled, as Santa Fe acquired hundreds of EMD FTs. By this time, SP was using 4-8-4s on its passenger trains, except for the heaviest trains, which had pairs of cab-forwards. This lasted until the end of steam in the mid-1950s.
The first SP diesels in the area were F3s in 1948, and dieselization was complete in early 1955. In diesel days, SP moved its western helper base to a spur track east of Sandcut and west of Bena.
By the time of the Union Pacific takeover of SP, in 1996, the technology for distributed power operations, controlling helper locomotives from the lead locomotive, had advanced sufficiently, that trains needing mid-train or rear-end assistance used this technology, with those locomotives running through between Roseville and West Colton or Los Angeles. The helper facilities between Sandcut and Bena were abolished.
21st Century Operations
Since 1996, the line over the pass has been owned by Union Pacific, and the trackage right have passed to BNSF Railway. In both 2005 and 2015, the traffic over the pass amounted to about 40 trains a day, two-thirds of them BNSF. The trains illustrated here are merely representative of the traffic over the pass. The train symbols and origin-destination pairs are shown in Traffic over Tehachapi Pass.
Maintenance and Reconstruction
Some of the trains operating over the pass are those used to keep the line in tip-top operational condition.