These are notes that I am writing to help me learn our industrial history. They are my best understanding, but that does not mean they are a correct understanding.
Monday, February 3, 2020
BNSF/SPS Bridges over Washougal River near Camas, WA
SPS = Spokane, Portland & Seattle Railway, a joint effort by GN and NP to compete with UP along the Columbia River.
Even though the bridge is near the mouth of the river with the Columbia River, there were too many obstacles between the old bridge and the Columbia River to use the float-out/float-in technique that was used with the Wood River replacement. They built skid beams on both sides of the old bridge so that they could slide the old spans out and slide the new ones in. They called this slide technique innovative. [rtands] But the Illinois Central slid new spans into place in the early 1950s. [CliffDowney] However, the IC let the old spans fall into the river. BNSF built skid beams to hold the old spans. I've seen the slide technique used more recently, but now I can't remember what the bridges were.
BNSF, the video linked to in this article is just one minute
Replacing the railroad bridge is budgeted at about $10 million, BNSF Railway spokesman Gus Melonas said....The track will not close for the project; the construction work will be done around the daily train traffic, Melonas said....Amtrak’s daily Empire Builder trains use that track....“Six hundred to 700 rail cars are switched daily at Vancouver, and currently 40 trains are operating through the Columbia River Gorge daily,” he said. “The Portland/Vancouver-to-Seattle corridor handles 50 to 60 train movements a day.” [Columbian]
These satellite and street views show how the spans varied in length and design to get the best trade off between pier and span costs. "The new bridge consists of a single-track, five span, 545-foot bridge including one 200-foot main span through truss, one 162-foot through plate girder span (TPG), one 92-foot TPG span and two 42-foot prestressed concrete double cell box beam spans." [TranSystems]
I'm surprised that the new deck holds only one track. Given the expenses of planning and environmental studies, of design, of the two temporary work bridges and of marshaling the construction equipment and supplies; I would think they would pay for the extra material needed to make the piers and deck wider. They could lay the second track later when it is needed.
The captions note when these Global Earth images were captured.
Apr 2015, old bridge
Jul 2016, the two temporary work bridges are partially built
May 2017, some of the new piers and spans are built
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