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Signs warning of high winds installed near Perrine, Hansen bridges

Gale-force winds and violent gusts often sweep across southern Idaho, sometimes strong enough to topple a vehicle. This scenario forced the closure of the Perrine and Hansen bridges a little more than a year ago. As a safety measure, ITD installed signs yesterday (Thursday, April 16) warning of these high winds near the entrance of both bridges.

Depending on weather, the signs were installed on Wednesday and activated this week.

On March 17, 2014, four trucks blew onto their sides, forcing the closure of both bridges. High-wind warnings and travel advisories were issued for high-profile vehicles and unladen trucks — vehicles that were either very tall or very light, and more susceptible to winds. While high winds forced vehicles onto their sides on other roadways, the bridges were the only areas where roads were closed for extended periods of time.

"We new that day that a better wind-advisory system was necessary," District Four Operations Engineer Walter Burnside said. "These bridges are a vital link across the Snake River, and any way we can reduce risk of their closure is worth consideration."

The signs will read "High Winds: Reduce Speed When Flashing" and be bordered by yellow LED lights. The signs will be linked to nearby ITD weather stations and will begin flashing when sustained wind speeds are at or above 35 mph. This wind speed coincides with the National Weather Service's wind speeds required for a high-wind advisory.

When the sign is illuminated, drivers of high-profile vehicles are encouraged to greatly reduce speed when traveling across the bridges. Caution and reduced speed are advised for all vehicles during periods of high wind.

During these times, ITD recommends drivers of high-profile vehicles should consider alternate routes. The nearest alternatives across the Snake River include U.S. 30 between Hagerman and Buhl, Idaho 46 between Wendell and Buhl, and Idaho 27 (Overland Avenue) in Burley.

Signs will flash for a minimum of one hour during gusty bursts and cease flashing when sustained winds drop below 35 mph.