The Ohio Department of Transportation will begin construction in April to remove the Interstate 71-U.S. Route 36 interchange from a list of the state's most dangerous.

The Ohio Department of Transportation will begin construction in April to remove the Interstate 71-U.S. Route 36 interchange from a list of the state's most dangerous.

"The department keeps a hot-spot list that ranks locations by how bad they are, and at one point the interchange was eighth on that list," said ODOT engineer Steve Fellenger. "It has since moved a little down on the list, but we expect traffic volume to double there in the next 10 to 20 years, so there's still urgency to the project."

Fellenger said 30,000 cars and trucks a day used the interchange in 2011.

"We've estimated that figure will climb to 64,000 ... over the next two decades," he said. "And 18 percent of that traffic is trucks, which we consider a high rate."

The interchange is the only exit along a 22-mile stretch of I-71.

ODOT recently briefed the Delaware County commissioners on the $4-million project.

The key elements of the project include:

• Dual left- and right-turn lanes on the northbound and southbound exit ramps to Route 36.

• An eastbound right-turn lane on Route 36 (in front of McDonald's) and a westbound right turn lane on Route 36 (in front of Flying J).

• Side-by-side, single left-turn lanes on the bridge over I-71.

The changes are designed to alleviate congestion, particularly on the exit ramps.

"If you've ever driven northbound on I-71 near rush hour, you'll see traffic begin to stack up anywhere from a mile to two miles south of the exit onto U.S. 36," Fellenger said. "We'll also be upgrading the traffic lights at the interchange and timing them up so that cars can move through more efficiently."

Between 2004 and 2006, the engineering firm LJB Inc. conducted a study showing 196 property-damage and injury accidents on I-71 between Africa and Galena roads. Eighty percent of the accidents occurred within 1,000 feet of the exit ramps.

"Significantly," Fellenger said, "more than 30 percent of the accidents were rear-end crashes, which speaks to the congestion problems at the interchange that will only get worse over time with growth and economic development in the region."

Fellenger said ODOT expects the construction to last a single season and be completed this fall.