NORTH ATTLEBORO -- Construction will begin soon on a three-lane highway in the median strip of Interstate 95 to be used while the Kelley Boulevard bridge is rebuilt. (With graphic)

Barrels and markers will be used to direct traffic onto the new lanes and under the middle of the bridge during repairs.

State highway department officials said Wednesday they believe the 1.25-mile bypass road will keep traffic moving on the interstate during the two-year project.

The bypass lanes will allow workers to rebuild the bridge over the interstate section by section, without traffic traveling directly under them.

Land-clearing for the three new lanes will begin next week. Northbound traffic will use the bypass lanes while construction is taking place on that section of the bridge, and southbound traffic will use them when work is proceeding there.

The bypass lanes account for about half the $5.88 million cost of the project, but state highway engineer Gerald Bernard said it is critical that I-95 traffic be kept flowing during the work.

Kelley Boulevard will also be kept open with one lane in each direction, while each half of the new bridge is built.

Details of the traffic plan were revealed at a meeting of about 20 officials from the state and town.

Bernard, resident engineer for the state highway department, said once the three lanes are in place, the west side of the bridge will be demolished. The west side of a new bridge will then be built.

While that is going on, all traffic on Kelley Boulevard, also known as Route 152, will travel on the east side of the existing bridge. Then the traffic will be switched to the west side while the east side is demolished and rebuilt.

Bernard said detours will be used only if there is an unforeseen emergency, such as a section of the bridge falling down.

The emergency detours will be Plain Street to West Street to Bungay Road and Landry Avenue through the industrial park to Toner Boulevard.

Both detours will be about 4.5 miles long.

The plan raised a number of questions at the meeting. Town public works board member Ray Stack asked if a $400,000 temporary sidewalk to be used during construction is really necessary.

He said he wondered if it would be cheaper to provide school busing over the bridge instead.

But Selectman Thomas Simms and state Rep. Betty Poirier, R-North Attleboro, said they thought it was important to keep the bridge accessible to walkers.

Michael Delaney, district construction engineer for the state, said the highway department has learned from past projects, including one in Duxbury, that the public wants sidewalks during construction.

Paul Briggs of Briggs Nursery, a Kelley Boulevard business, expressed concern about traffic being stopped on the road and asked for some changes in sign locations.

The state engineers agreed to move the signs and said the only time there would not be two lanes open over the bridge is if equipment had to be moved.

Those operations would only last between 30 minutes and an hour, and police could direct traffic over one lane, they said.

Bob Ellston of the town electric department said the state has not contacted him yet about moving a utility pole under the bridge.

Delaney said the paperwork is in the mail.

In response to questions about public safety, Bernard said there is enough room on Kelley Boulevard to pull traffic over to allow police and fire vehicles to pass.

Bernard said the project is scheduled to be completed in August of 2002. He said some preliminary work has already begun.