Iowa DOT road crews turn to sirens to warn drivers off a collision course

IOWA CITY — Five Iowa Department of Transportation crews were hit while doing roadwork in 2020. Two workers lost their lives. This year, four Iowa DOT crews have been struck by motorists.

“Our crews have a sense of duty to get the job done,” said Brad Fleming, maintenance director for Iowa DOT in a statement. “They are dedicated to their work, but we have very few employees who haven’t seen or been involved in a near-miss or a crash due to an inattentive driver.”

The department is hoping that a new addition to an old piece of equipment will be the key to keeping workers — and motorists — safe. They’re called audible attenuators, and they can be loud.

Fleming told The Gazette attenuators have been in use by road workers for more than 20 years. Either mounted on a dump truck or pulled behind crews on a trailer, attenuators are designed to be hit by vehicles, absorb the impact of the crash and protect employees and the public. Because of the number of hits or near-misses, employees are less willing to drive attenuator trucks these days, according to the Iowa DOT.

But an audible addition to the attenuators added in the last year and a half could make work safer for crews. Attenuators are equipped with flashing lights and signage, and operators have the ability to turn on additional flashing lights that blink at a higher frequency to alert an oncoming driver to slow down or move over. If that still isn’t effective, operators of the audible attenuators can activate a siren to get the oblivious driver’s attention.

“It is a fairly loud siren,” Fleming said. “It will definitely get someone’s attention at highway speeds. It’s got to be loud to overcome the noise.”

Hear what an attenuator siren sounds like in this video from IDOT:

“Anytime it has been activated, we haven’t been hit,” he said. “It has gotten the drivers attention. We are currently putting more of them into play and see this as a very valuable tool to keep the traveling public — as well as our workers — safe in these work zones.”

The attenuators are used on short-term, stationary or slow moving operations, according to the Iowa DOT.

The Iowa DOT currently has 39 audible attenuators distributed to crews across the state with plans to add another 35 this year, Fleming said. The initial rollout focused on metropolitan areas — including Cedar Rapids and Iowa City — but Fleming said he plans to make sure that any state maintenance garage responsible for a four-lane stretch of highway has access to one.

A department of transportation work truck is seen staged with a safety barrier trailer and light board to alert drivers of work being done ahead at the DOT maintenance shop in Cedar Rapids on Wednesday, May 5, 2021. (Andy Abeyta/The Gazette)

The speaker for a siren is seen mounted on a department of transportation work truck at the DOT maintenance shop in Cedar Rapids on Wednesday, May 5, 2021. The siren gives an audio alert to drivers who dont get over a lane for construction work ahead and can be activated by the trucks operator when necessary. (Andy Abeyta/The Gazette)

Caution lights are seen on a trailer hitched up to a department of transportation work truck at the DOT maintenance shop in Cedar Rapids on Wednesday, May 5, 2021. (Andy Abeyta/The Gazette)

An Iowa department of transportation truck is seen at the DOT maintenance shop in Cedar Rapids on Wednesday, May 5, 2021. (Andy Abeyta/The Gazette)

Caution lights are seen on a trailer hitched to the back of a department of transportation work truck at the DOT maintenance shop in Cedar Rapids on Wednesday, May 5, 2021. (Andy Abeyta/The Gazette)

Fleming said the idea for the attenuators came from the Missouri Department of Transportation, though the Iowa DOT modified the concept. Components like speakers are ordered, but the framework and assembling of the attenuators is done at the Iowa DOT’s central repair shop in Ames. They cost about $10,000 apiece.

Even with the devices in place, Fleming said attentive driving on the part of motorists still is key to keeping workers and drivers safe.

“We just want to make sure all of our employees, as well as the traveling public, are going to make it home safe,” he said.

Comments: (319) 339-3155; lee.hermiston@thegazette.com