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I will be covering this portion of the Union Pacific from west to east since most of my trips across the territory were made in that direction. From the time the railroad connected with the Central Pacific to the end of the century, the UP was only able to add about 17 miles of second track. Early semaphore signals were installed between 1906 and 1917.
With increased traffic and the leadership of Harriman the railroad transformed the single track Overland Route to mostly double track by the end of 1918. In 1909 the UP began installing block signals between Ogden and Salt Lake City on 30 miles of single track and 7 miles of double track. Also in 1909, it was adding a second track between Rock Springs and Green River, WY. The single track already had signals. The single arm signals were converted to double arm and used on the second track. Signals were spaced about a mile apart. UP added a second track between Ogden and Devil's Gate in 1916 and then Emory to Wahsatch in 1917. In 1923, UP installed 25 US&S style B lower quadrant semaphore signals between Emory and Echo on 10 miles of double track. Double tracking was completed from Ogden to Green River in 1926. The original mainline through Weber Canyon was 1.72 percent. The newer track was added on a slightly different alignment and was only 1.14 percent. The new track became the eastbound line and the original mainline was then used for westbound trains. During 1942 the UP did extensive work replacing semaphore signals with US&S color light signals. Green River to Ogden got 279 signals on 176 miles of double track. In 1974, the Union Pacific installed CTC from Ogden 20 miles east to Strawberry.
Salt Lake City