Iowa DOT Adds ‘Audible Attenuators’ To Their Safety Fleet

Statewide Iowa — The Iowa Department of Transportation has added another tool to help reduce the risk to their crews, as well as everyone else on the road.

With spring comes summer maintenance for the IDOT, like patching potholes and painting road markings. These activities often take DOT workers out of their trucks onto the roadway, dangerously close to speeding traffic.

To help reduce the risk the DOT has begun the use of audible attenuators on short-term, stationary, or slow-moving maintenance operations. The attenuators are designed to warn drivers of crews ahead and take the impact of a crash if a driver does not slow down or move over for the crew.

DOT officials say an attenuator is a trailer that is pulled behind a truck equipped with flashing lights and signage signaling the presence of crews. If a driver does not appear to slow down or move over for the crew, the attenuator operator has the ability to turn on additional flashing lights that shine at a higher frequency. If a driver is still not responding to the extra lighting, the attenuator operator can then activate an audible sound in a final attempt to get the attention of the driver.

DOT workers being hit is an ongoing problem. In 2020, there were five crews hit and two DOT workers lost their lives. So far in 2021, there have already been four crews hit by motorists.

When drivers aren’t paying attention, sounding the audible attenuator is designed to be loud enough to get the attention of the driver and has the added benefit of signaling to everyone around that the crew is in imminent danger of being hit.

DOT officials say that although you may not be aware of these audible attenuators, they are very similar to fire or law enforcement sirens. Just like those sirens, these audible warnings are used to increase the safety of not only DOT crews but all of those who share the road.

The Iowa DOT currently has 39 audible attenuator systems in place and 32 more systems should be in place this year. Each system is built by Iowa DOT staff and costs approximately $10,000. While the current systems are manually triggered by an operator driving the attenuator truck, officials says testing will begin this spring on an automated version of the system that will be triggered when a vehicle approaches a work zone too quickly or too closely.

To see and head one of the audible attenuators in action, check out the video below…

Video from the Iowa DOT YouTube channel

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