Bridge collisions in Idaho: What every driver needs to know

IDAHO FALLS, Idaho (KIFI) - The southbound lanes of Yellowstone Highway were shut down for hours last Thursday due to a semi truck hitting the bottom of the bridge.

Accidents of this nature are more common than you'd expect, according to the Idaho Transportation Department.

"It's typically contractors hauling construction equipment, maybe having an excavator on the back of a truck and it's not fully collapsed," ITD spokesperson Megan Jahns said. "They don't realize how tall they are. And so they smack into the bridge so the drivers can mitigate all of this by checking their load for their hides and paying attention to signs like not to bridges to know if they can make it under or not."

All bridges in Idaho are designed according to Federal regulations to be around 14 feet tall, according to the ITD; however, most Idaho bridges are built 17 feet tall. That provides at least six feet of clearance to a standard semi-truck.

If the bridge is any shorter than 17 feet, ITD posts signs to alert the driver, which means it's the driver's responsibility to know if their haul is too tall for the bridge.

Lynn Jorgensen with the Sage Truck Driving School said the best course of action for truck drivers is preparing ahead of the trip.

"They'll do a pre-trip route and know exactly what each overpass height is. If they're very unfamiliar with the area, this can be a problem, and that's why trip planning should be one of their cases that they should look for," Jorgensen said.

But he says inaccurate information on GPS systems have led to problems as well.

While researching this issue, we were able to find an online mapping site to tracks routes to help semi truck drivers avoid low clearance bridges. For more information, click HERE.

According to Jahns, ITD responded to 8 bridge collisions in 2023. They have found evidence of several more strikes that were never reported.

In fact, last October there was a semi-truck that struck the bottom of a bridge in Shelley.

That collision damaged the bridge so much ITD was only able to safely open up one lane of the structure this January.