It has long been a source of frustration for motorists, particularly those visiting Maine for the first time.

A motorist traveling from Kittery to Bangor enters the state on Interstate 95, which quickly becomes the Maine Turnpike. Along the way, the same stretch of highway becomes I-495 and then reverts back to I-95.

The exit numbers are confusing as well because numbers are duplicated or are similar to other exits.

In 2004, Maine transportation officials hope to end the confusion by renaming exits that correspond with mile markers and altering highway names so I-95 keeps the same designation all the way through the state.

The changes mean the entire stretch of interstate from Kittery to Houlton will be known simply as I-95. The entire spur that extends from Scarborough to Gardiner, skirting downtown Portland, will become I-295.

Gone forever will be the I-495 designation through Lewiston-Auburn that confounded tourists on the Maine Turnpike.

The work begins Jan. 5, and it will take about 10 days to post new signs on the interstates. Simplification efforts will continue on May 15, when crews begin renumbering highway exits.

Dan Paradee, spokesman for the Maine Turnpike Authority, said the changes make sense. The old highway names, he said, were held over from when the original turnpike was built in 1947.

“There is a logical explanation for it being the way that it is, but it’s hard to figure out,” the spokesman said. “It doesn’t make any sense from a driver’s point of view.”

Paradee hopes the changes will go smoothly, but he noted there could be some confusion as the signs change.

“There will be a week in there when we’ll be in limbo, with both kinds of signs in some places,” he said. “That could make it a little interesting.”

The new exits will be numbered based on their mileage from Kittery, not the number of exits. Under the new plan, Auburn’s Exit 12 becomes Exit 75. Lewiston’s Exit 13 becomes Exit 80.

Gone forever will be several sources of confusion, including the fact that there are two Exit 2’s (one in Kittery on I-95, and one in Wells on the Maine Turnpike). Exits 3 and 4 are duplicated on I-95 as well.

Paradee said Maine’s mileage-based numbering system for exits trails a nationwide trend.

“I think New England is among the last holdouts for a sequentially based numbering system,” he said.

He said all of the changes, including the new exit numbers, should be completed by Memorial Day weekend.