Clarks Bridge at Lake Lanier will close for 60 days or fewer as part of a three-year, $7 million replacement project, Georgia Department of Transportation officials said Wednesday.

The closing will take place about two years into the project, which is estimated to start in the fall, said Teri Pope, spokeswoman for the DOT's Gainesville office.

The closing is needed so that workers can build approaches to either end of the bridge, as well as a 63-foot pedestrian tunnel connecting Clarks Bridge Park and Lake Lanier Rowing Club/Lanier Canoe and Kayak Club's boathouse to the Olympic venue and boat ramps.

"There is some grade change in order to put this pedestrian facility in," said Robert Mahoney, preconstruction engineer for the DOT. "You have a set elevation of the lake that you can't deviate from, so we actually have to pick up the grade of the road a little bit as we come off the new bridge."

Mahoney gave an update on the project at the Gainesville-Hall Metropolitan Planning Organization's Technical Coordinating Committee, a group of area engineers and planners who meet quarterly to discuss transportation issues.

The tunnel, expected to cost $200,000, is actually a concrete box culvert that will be 10 feet wide and 8 feet high.

"It is precast so it comes to the site in sections (that) have to be moved into place and joined together for the length needed," Pope said.

Workers will spend about two years building the new bridge, which will feature two 12-foot vehicle lanes, as well as 4-foot bicycle lanes and 5-foot sidewalks in each direction.

Overall, the new bridge will be 952 feet long, nearly 50« feet wide and have five columns in Lake Lanier. Bike lanes and sidewalks will run along Ga. 284/Clarks Bridge Road for 2,781 feet.

The current bridge, built in 1958, is 834 feet long and nearly 24 feet wide.

The new bridge will be built next to the existing bridge, so traffic can flow normally during construction. Once it is finished, workers can build the approaches and install the tunnel.

The DOT will set up an 11.2-mile detour with traffic directed north on U.S. 129/Cleveland Highway to Ga. 284 in Clermont and then directed south toward the bridge.

Several roads, such as Honeysuckle Road, Lakeview Street and Lakeland Road, connect the two arteries.

"We don't divert state route traffic onto a local road," Pope said. "Local roads just aren't built to handle that traffic. Some of them are only 6 inches deep.

"Also, if we use local roads, we could cause all kinds of pavement condition problems."

The DOT is "requiring that the detour ... be 60 days or less or the contractor will be fined," Pope said.

The original estimate was four months, she added.

Once the new bridge, approaches and tunnel are in place, the old bridge will be torn down.

"That's part of the construction contract," Pope said.