Hansen Bridge

Trucks drive across the Hansen Bridge on Sept. 27 near Hansen. The Hansen bridge was built in 1966, making it the oldest operational bridge in Twin Falls.

PAT SUTPHIN, TIMES-NEWS

HANSEN — The Hansen Bridge has a more rural feel to it than its western neighbor.

No shopping centers or restaurants light up the rims on either end. The chain-link safety fence is not as impressive as the stone walls beneath the I.B. Perrine Bridge. And to the casual spectator, there’s nothing particularly eye-catching about its architecture.

But on Sept. 27, the bridge and its spectacular canyon views were enough to entice visitors. As road construction narrowed traffic to a single, alternating lane, several cars pulled over into a lookout area.

One couple, on their way home to Kansas, took a detour specifically to see one of Idaho’s “high bridges.” They poked along a trail while other travelers read informational signs about the area’s attractions.

While the Hansen Bridge may not be as widely recognized as the Perrine Bridge, it still garners significant attention and is the site of the original Snake River Canyon crossing in Twin Falls County.

How it came to be

The Hansen Bridge was constructed in 1966 to replace the 1919 Hansen Suspension Bridge.

The original bridge had 14 cables and cost $100,000. It had been built 17 feet wide — just enough for two horse-drawn wagons to pass.

The Hansen Suspension Bridge had been designed to hold only 10 tons, but loads heavier than that had been known to bend, but not break the structure during its 47-year lifespan.

“But while it has been around the proud old bridge from the horse and buggy days of this part of Idaho has done a job,” wrote O.A. (Gus) Kelker in an April 3, 1966, Times-News article. “More of a job, in fact, than it was ever called to do.”

The replacement, 762.5-foot steel girder bridge was built 74 feet longer than the original, and 15 feet higher above the canyon floor, as the original bridge dipped at each approach. It cost more than $1 million.

Both bridges carried the name Hansen, recognizing the work of John F. Hansen and Lawrence Hansen to enlist public support in the original project.

Bridge improvements

In 2003, the state removed 1.5 inches of the original deck and added 3.5 inches of concrete overlay, making the new deck 9 inches thick. ITD also replaced expansion joints, spot painted rusted areas of the steel girders and repaired cracks on piers. Other surface improvements were made in 2012.

This year, ITD limited bridge traffic to one lane to do multiple repairs. This included an epoxy overlay, which protects the bridge surface from the elements. Workers also repainted the steel girders to keep oxidation and rust out of the steel.

Finally, they extended the drain pipes below the bottom of the girder, since they had contributed to the main beams’ corrosion.

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How it’s holding up

As of June 2016, the deck and the substructure — what’s holding up the surface — were in “satisfactory” condition, but the superstructure was in “fair” condition. The bridge is inspected every two years.

“The Hansen Bridge is in good shape for its age,” ITD spokesman Nathan Jerke said.

In 2016, the bridge had 8,100 vehicles per day crossing it.

ITD District IV Engineer Devin Rigby said major repairs will be needed in 15 to 20 years. Its greatest restriction to meet traffic needs will be the fact that the bridge has only one lane in each direction, and no additional lanes are possible.

Expected lifespan

The Hansen Bridge is expected to reach at least its 75th birthday, Rigby said.

“Any capacity needs would probably be the driver for what we do next,” he said.

A 2008 ITD study estimated that 9,500 vehicles will cross the Hansen Bridge per day by the year 2030.

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