After more than 20 years of planning and a year and a half of construction, the new Settler's Cabin interchange on the Parkway West in Robinson opened to traffic for the first time yesterday.

Allegheny County officials said the $28.8 million project would ease traffic congestion along the parkway. It includes an overpass that links Bayer Ridge and Campbells Run roads.

"I was still in college when this project was getting started," County Chief Executive Dan Onorato said before a ribbon-cutting ceremony near the overpass.

He touted the site as an important part of one of his top priorities as chief executive -- promoting development around Pittsburgh International Airport.

"Probably the biggest economic opportunity in Allegheny County is the airport corridor," he said. "The interchange is going to play a key role."

Bayer Corp. contributed about $4 million to the project, said Tom Donatelli, the county's public works director. The company's nearby headquarters houses more than 1,400 employees, who will make use of the new overpass.

The county's share was $5 million. The rest of the cost was covered by the federal and state governments, Robinson and the Robinson Park Associates.

The project closed a portion of Campbells Run Road from February of last year until this week, forcing 15,000 motorists to find alternative routes.

The county and the Pennsylvania Department of Transportation have started design work on the project's second phase, which will widen Campbells Run between Baldwin Road and Route 60.

It also will widen the parkway between the Interstate 79 interchange and the Campbells Run Road exit.