Trucks running at more than 84,000 pounds are costing the state of North Carolina about $130 million a year, according to new research from the state’s Department of Transportation.

With some help from a new set of pavement standards released in 2002, Judith Corley-Lay, head of the DOT’s Pavement Management Unit, was able to use weigh-in-motion stations and typical pavement configurations to determine how much damaged was done by trucks running over weight, and then used standard economic formulas to determine the cost of the damage.

“I was asked by the state highway administrator to look at the issue of the cost of overweight trucks in particular, and the cost of axle-weight exemptions to the highway pavement system in North Carolina,” Corley-Lay told Land Line. “That is a very complex question, because any given roadway can have a wide variety of trucks on it, as well as all different levels of normal automobile and lightweight truck traffic.

Corley-Lay analyzed a number of different types of roadways, including high volume and low volume primary and secondary roads, and interstate highways, to create a composite analysis. The data was measure by weight on each axle, rather than on overall vehicle weight. Passenger vehicles were also recorded, but that data was not analyzed for this portion of the study.

For vehicles over 84,000 pounds, Corley-Lay found costs to be around $85 million. The cost for weight-exempt vehicle – such as agricultural, timber and trash haulers – was close to $44 million.

Despite this being one of the first studies nationwide to put a price tag on overweight truck damage, Corley-Lay said she believes the study to be fairly accurate, and the first real scientific progress made toward applying dollar amounts to road damage.

“This is the kind of question that I get asked almost every year, or every other year, depending on the legislative agenda, but I’ve never really been able to calculate a dollar figure before,” she said. “I expect this is the first of many, and frankly, it’s a calculation that I think most DOTs are asked to make in one form or another.”