AUGUSTA – The Nov. 20 opening of a new Kennebec River bridge linking Interstate 95 and Route 3 will do more than provide a faster route for motorists heading between southern Maine and points Down East.

The project is expected to set the stage for changes that will dramatically transform Maine’s capital.

The more immediate change should be a noticeable decrease in the volume of traffic, especially 18-wheel trucks, along Western Avenue and Augusta’s two traffic circles.

Over the long term, the project is expected to promote significant retail and residential development on the city’s east side, in the Riggs Brook area just north of the new section of Route 3 leading to the bridge.

The east side is “a gem in the rough,” said Michael Duguay, the city’s director of economic development.

The $10.9 million bridge, which is yet to be named, crosses the Kennebec about a half-mile north of the downtown, where the water’s tidal influence ceases. The overall project, with three overpass bridges and four miles of access roads, cost about $44 million. The federal government is paying 80 percent.

The state Department of Transportation projects that 18,000 vehicles will cross the bridge in 2005. DOT planners also predict that the new bridge will lighten the traffic load on Western Avenue between the Augusta armory and I-95 next year, from 42,000 to 33,000 vehicles a day.

The bridge should also reduce the number of cars and trucks using the two-lane Memorial Bridge from 33,000 to an anticipated 25,000 per day in 2005.

The drop in vehicles on Western Avenue during tourist seasons could hurt some local businesses, such as restaurants and retail shops. But Vaughn Stinson, director of the Maine Tourist Association, said proper signage on the Maine Turnpike and I-95 would make tourists aware of those services in the city.

“They [the Department of Transportation] need to be really keen on signage,” he said. New signs also would help make tourists note Augusta’s local attractions, including Old Fort Western, so they do not entirely bypass the city for points north and east, Simpson said.

John Melrose, DOT commissioner from 1995 to 2002 who helped plan the new bridge, said the project was supported by legislators in coastal towns who saw an easier link to major arteries.

Augusta officials saw a new span as a way to enhance safety after a steady increase in traffic on Western Avenue, the two rotaries and Memorial Bridge.