LEWISTON — A narrower turnpike interchange at Exit 80 would make it easier and less expensive to build, highway engineers say.

Representatives from the Maine Turnpike Authority and engineering firm HNTB presented plans for a streamlined interchange to a group of about 20 residents and city officials at the Ramada Inn on Wednesday. The plan would send turnpike traffic down Plourde Parkway and through a single traffic signal.

Roland Lavallee of HNTB said the authority considered two other plans before settling on the single-point design.

“It’s designed for traffic loads in 2030, so when we build it today it will seem like there’s no traffic at all,” Lavallee said. “And in 2030, it should move very smoothly.”

Lavallee said the authority considered keeping the exit’s current design: All of the traffic for northbound lanes — either exiting or getting on at Lewiston — would stay on the southwest side of the interchange. It’s a steep lane for traffic getting on the turnpike and a sharp turn.

The authority also considered using a traditional diamond interchange design, like the Maine Turnpike’s exit in Sabattus. That would involve buying as much as 54 acres of land on the turnpike’s southeast side.

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The single-point design would use much less land. It would require the Turnpike Authority to take over about 3.6 acres on the southeast side and could result in the authority selling land on the southwest side.

“When we looked at the costs associated with the three plans, redoing the current design was least expensive,” Lavallee said. “But when we factor in the land costs, the single-point design makes the most sense.”

According to plans, the project would be built in phases. The first phase would be to build a new northbound onramp in the interchange’s northeastern quadrant. The existing southbound onramp would be rebuilt and reconfigured.

The second phase would focus on reconfiguring the northbound and southbound offramps. The final phase, due to be completed in 2013, would build a bridge carrying turnpike traffic over Plourde Parkway.

Officials are estimating the work would cost $22 million. That would be split between the Turnpike Authority and the Maine Department of Transportation. The authority has set aside $17.5 million; MDOT, $5 million.

The work replaces plans for a downtown interchange that had been proposed near the river — either building new interchanges on River Road in Lewiston, on Route 136 north of the turnpike in Auburn or on both sides of the river.

A study by the Androscoggin Transportation Resource Center found that a new interchange wouldn’t get turnpike traffic to the Twin Cities’ downtowns faster, no matter where it was located.

staylor@sunjournal.com

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