The UP Gila Sub is the ex-Southern Pacific Sunset Route that runs 255 miles from Yuma, AZ, to Tuscon, AZ. UP is slowly getting ready thru PTC upgrades or double tracking projects to replace any remaining ex-SP searchlight signals along this route. Roughly only 85 miles of original SP trackage is left with old signals along the Gila.
Between Dome and Wellton, there is 16 miles of original SP double track. The 2nd track was built in 1926, with the original main built by the end 1879. While it shows 2 main CTC, the trackage is signaled basically in one direction like traditional ABS. Here a intermodal train from Marion, AR, to Global Gateway South (San Pedro, CA) eases up to the signal at the end of double track at Dome. Common place for meets to go on for trains coming out of Yuma.