What Fleet Managers Should Know About Impact Attenuators

An impact attenuator is a safety device, either mounted on the rear of a truck or towed as a trailer, that absorbs the force of a vehicle collision at speeds up to 62.5 mph to protect roadside crews working nearby.

While attenuators are not a new concept – they’ve been in use in the highway construction industry for decades – what is new is that they’ve started to become more prevalent in the utility industry.

“Utility companies are a new market for us,” said Brent Kulp, executive vice president at TrafFix Devices Inc. (www.traffixdevices.com), which builds both truck-mounted and trailer impact attenuators. “Typically, we sell to the highway departments. But beginning about five years ago, utility companies started coming to us, saying, ‘Hey, our guys are out on the highway, out on the city streets, fixing a gas line or doing a utility pole repair. We want to protect our crew working in front of that vehicle from distracted drivers.’”

A Roadside Crash ‘Pillow’
In theory, orange traffic cones should be sufficient to alert drivers and safely direct them around the job site ahead. But in reality, distracted driving has increased the risk that drivers won’t notice those cones until it’s too late.

“The mobile phone is the biggest distraction of our time,” Kulp said. “We all drive down the road, and you see a distracted driver, the car weaving around, because they’re sending a text message, not paying attention. It’s so dangerous.”

Eric Smith, TTMA (trailer truck-mounted attenuator) product manager and highway marketing manager at Gregory Highway (www.gregoryhighway.com), agreed that distracted driving has caused fleets to look for ways to provide extra protection for their roadside workers.

“The attenuator protects the impacting vehicle, the motoring public and the workers in that work zone,” Smith said. “It’s like a pillow – a crash cushion – for a vehicle to crash into and safely bring it to a stop.”

How do attenuators work to absorb energy from a collision?

“[The TrafFix] ‘Scorpion’ system works with a series of aluminum honeycomb boxes that are very lightweight, designed to absorb the energy and collapse as a vehicle hits it,” Kulp said. “And then holding those honeycomb boxes are curved aluminum tubes which bend as a vehicle impacts the back of that attenuator, further absorbing the energy.”

According to Smith, “[The Gregory] attenuator uses a guardrail technology, with a mandrel inside of a square tube. In a collision, the force of the mandrel pushes through the square tube, and those forces work against each other to create the energy absorption.”

How much do attenuators cost?

Kulp said the price range is about $20,000 to $30,000 per unit, depending on the attenuator type and other factors.

Truck-Mounted vs. Trailer Attenuators
There are two types of attenuators: truck-mounted and trailer. So, how do you determine which one is right for the job?

Keep these two points in mind.

1. Flexibility
“If the truck will be used in primarily forward-moving or stationary operations, and you want the versatility to switch the attenuator from truck to truck for different jobs, then a trailer attenuator fits that application perfectly,” Smith said.

Kulp agreed. “One day you need to use the truck as an attenuator, so you hook the trailer to it. But maybe the next day, you don’t want an attenuator on that truck because that vehicle will be used for a different operation. The trailer gives you that flexibility.”

One caveat about using a trailer attenuator: It must be hooked to the truck when it’s on the job. “If a vehicle hits that attenuator and it’s not attached to a truck, that trailer is going to get launched,” Kulp said.

2. Maneuverability
If you’re sending crews for roadside work in tight areas, such as city streets, consider the truck-mounted option.

“The truck-mounted attenuator makes the vehicle much easier to maneuver than it would be if it were pulling the trailer,” Kulp said. “The trailer is about 18 feet. But our Scorpion truck mount, when deployed, is only 13 feet. And when the attenuator is stored in the travel position, there’s only about a foot-and-a-half overhang. So, the truck-mounted attenuator is much more compact and makes it much easier to travel to the job site.”

The Bottom Line
As distracted driving becomes more and more of an issue, impact attenuators offer extra protection for roadside utility crews. “It’s all about safety,” Kulp said. “You’re protecting your crews – and the drivers – to be able to walk away from what could have been a catastrophic crash.”