TWIN FALLS — Blink, and you might miss it.
As you drive Pole Line Road out of Twin Falls, it’s easy to overlook the 498-foot bridge over Rock Creek Canyon. One moment you’re on it, and the next you’re cruising past 2600 East and toward more acres of sprawling farmland. Until you look at it from the side, it might not look like a bridge at all.
This is one of three rim-to-rim crossings over Rock Creek canyon in the Twin Falls area. About 13,000 vehicles cross the bridge every day. The majority are passenger vehicles, but 400 are commercial vehicles.
How it came to be
Much like the bridge itself, the history of the U.S. 93 Rock Creek Bridge is short and sweet.
The bridge was constructed by W. W. Clyde & Co. and was dedicated Dec. 8, 2010. Its construction was a part of the Twin Falls alternate route project to widen Pole Line Road in an effort to divert traffic around town.
“We really recreated a bridge structure that was historically there,” Idaho Transportation Department spokesman Nathan Jerke said.
This bridge replaced an earthen fill, where the canyon was filled in with soil and Rock Creek was channeled through twin pipes. Prior to that project, a wooden bridge spanned across the canyon.
Fills create fewer concerns about failures, but make the widening of a road more difficult, City Engineer Jackie Fields said. Furthermore, recreating the stream bed and restoring the original canyon walls to lessen environmental impact factored into the decision to build a real bridge.
The steel girder bridge was designed to eventually be widened to accommodate six lanes of traffic, though Jerke noted adding two lanes would eliminate the shoulder and pedestrian safety.
Improvements since then
Idaho Transportation Department did an epoxy overlay on the bridge deck in 2011. It is still “many years” from needing additional lanes —and that probably won’t happen unless the city grows out that far, Jerke said.
How it’s holding up
An August 2017 inspection showed the entire bridge was in “very good” condition.
“The concrete’s probably still getting harder,” Jerke said.
This bridge was built to have 50-year lifespan.