KNOXVILLE, Tenn. (AP) When a section of Interstate 40 at downtown Knoxville closes for more than a year beginning this summer, it will mean a change of plans for thousands of motorists on the major cross-country corridor.

The closure between James White Parkway and Hall of Fame Drive begins May 1.

Tennessee Department of Transportation contractors are working on letting drivers know how to negotiate the detour with about 270 sign changes leading into the city.

The detour will carry motorists on I-640 around the city, which means signs are being posted in advance miles away on I-40, 75, and 81.

“There are so many signs, we can’t just snap our fingers and do all this in one weekend,” Mark Dykes, TDOT’s regional safety coordinator, told The Knoxville News Sentinel.

“We plan to have all the signs in place by May 1. So you may see the signs up a week before May 1. You may be directed by signs to 640 but the downtown route is still open.”

Crews with Tennessee Guardrail Inc. will be erecting 18-by-14-ft. signs in Greene, Cocke, Roane, McMinn, Loudon and Jefferson counties to warn them of the closing. They will be covered until May 1.

More signs will be posted closer to May to warn of specific lane changes to funnel traffic onto the detours. All the sign-posting could have some impact on traffic if existing posts can’t be used.

“There’s going to be some night work and weekend work, but there’s still going to be some impact on traffic,” company vice president Kevin Peel said.

The $190 million SmartFIX40 project is expected to improve historically poor traffic flow through Knoxville.

The construction will widen downtown I-40 to six through lanes and four auxiliary lanes. Nine bridges, 14 retaining walls, three noise walls and seven ramps will be built. A dozen side roads will be completed and two bridges will be demolished.

The work is supposed to be done by June 30, 2009.

SmartFIX40, which began in 2006, is the single most expensive undertaking in the 90-year history of the Tennessee Department of Transportation. It relies on round-the-clock construction to shave months off the typical roadbuilding timetable.

Meanwhile, transportation officials will begin a study in August to look at north-south I-75 with hopes of relieving traffic congestion on the route from Florida to Michigan.

Georgia and Kentucky already have agreed to widen their parts of the interstate to six lanes, Ralph Comer, TDOT’S assistant planning director, told the Chattanooga Times Free Press.

“You sort of have a gun pointed at Tennessee,” Comer said.

The study will explore whether to widen the interstate to six lanes or other solutions could help ease the flow, such as alternative routes for freight.

The study will last 18 months. It would cost about $1.7 billion to add an extra lane in each direction for all 160 mi. (257 km) of I-75 in Tennessee.

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