Central Pacific Railroad Photographic History Museum
posted from CPRR Discussion Group at 5:00 PM
In the twentieth century, 1906-1925, a second track was added and other improvements were made.With the exception of a few sidings and passing tracks, when the Pacific railroad (CPRR/UPRR) was completed in 1869 it was entirely a single track line. While the original Sierra tunnels were bored using hand drilling and black powder, with the advances in tunnel boring (mechanical drills and TNT), and the decision to double track the line, over the first quarter of the Twentieth Century a second set of tunnels were bored for the second track (the only double track tunnel on the line is #18 at Newcastle), a few sections of the track were realigned, and a second grade was created where not enough room could practically be made to add a second track on the original grade such as at Bloomer Cut. The last of the tunnels bored (1927) was the two mile long tunnel #41 ("The Big Hole") under Mt. Judah which is just south of the original Donner Pass summit grade through tunnels #6, #7 & #8. (You can see this tunnel marked on the map at the top of the Donner Pass gallery page.) When this double tracking was completed, the new track (#2) became the default Eastbound track, and track #1 was used mostly for Westbound traffic. (Track #1 occupies the original grade for the most part, but at a few places such as Cape Horn the original grade is occupied by Track #2.) In the early 1990's Southern Pacific management decided to remove some of the double tracking to "save money" and one of those places was where the line split just one mile west of Donner Pass at shed #41 at Norden. Old Track #1 through tunnels # 6-8 and the snowsheds was removed and a new Track #1 was realigned to run next to Track #2 to Tunnel #41. Here it merges into a single track alternately serving both eastbound and westbound traffic. (The tracks split again into Tracks #1 & #2 at Eder just East of The Big Hole.) ... Track One (the original grade) was largely abandoned during the realignment, the new grade runs from 10 feet to 75 miles off the original grade. The grade thru Rocklin is near the original grade, however Track 2 (the new, second line installed in 1908-1012) leaves Track 1 just East of Rocklin.Summit Tunnel over the Sierra Nevada's was removed from use in 1999, and the tracks removed.
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