Motorists pass by all the time, they may or may not think much about the work going on, but MoDOT says its workers are always thinking about the traffic coming from behind-especially the person behind the wheel of the shadow truck that trails behind.
“It’s a very odd feeling looking into that rearview mirror, and you see a truck or a car barreling down on you. And you just hope they can get over, and there’s nothing you can do about it if they don’t,” explained Chris Redline, District Engineer for MoDOT Northwest District.
Redline is concerned about the drivers of the modified dump truck called Truck Mounted Attenuator, or TMA. It’s a rear warning truck for slow moving work zones like striping or sweeping. Redline said MoDOT is entering the next phase of a pilot program for rear vehicles in slow moving work zones to become driverless. This is to spare MoDOT workers from harm.
“This is the right thing to do,” said Redline. “We have employees getting hurt every year. We have several employees who have actually been hit twice.”
The chambers of the TMA attachments are filled with energy absorbing material, designed to cushion the blow. It can save motorists and workers from life-threatening injuries, but not always.
Mark Croarkin is MoDOT’s St. Louis District’s assistant engineer. He’s had several injured employees and is concerned about the increasing rate of crashes in the St. Louis District.
Over the last four years, MoDOT reports an average of 29 hits a year with the St. Louis area experiencing more vehicles crashing into TMA’s than other parts of the state. In the first three months of 2020, there were 13 TMA crashes statewide with nine of those crashes in just the St. Louis District. This is a big jump from the first quarters of previous years, almost double what the state of Missouri experiences in the months of January through March.
“In general, it’s high speed and erratic driving,” explained Croarkin. “Out of the 13 TMA hits statewide in the first quarter this year, half of those were hit and runs.”
Many wrecks are also caused by distracted drivers. The high volume of traffic in the St. Louis area factors in. Croarkin said driverless TMA trucks with autonomous technology is the best protection for workers.
Kratos Defense & Security Solutions in Florida retrofitted two of MoDOT’s TMA trucks with autonomous technology, using a leader-follower method. The vehicle would be in the rear of a striping or sweeping work zone convoy.
“You’re talking about speeds of nine miles an hour,” explained Redline. “To get to the jobsite, it will be driven manually. It will be staged on the shoulder and then be put into leader-follower mode.”
The project in Missouri’s Northwest Region is federally funded and costs approximately $549,000. The St. Louis District recently applied for a federal research grant to extend the pilot program to the St. Louis area.