The Pennsylvania Department of Transportation’s redesign of the Green Tree interchange on the Parkway West will eliminate the two loop ramps motorists use now and put more traffic directly on expanded neighborhood roads.
The agency unveiled the $105 million plan to improve safety and traffic flow Wednesday evening at a meeting in the Green Tree Borough Municipal Center. The project is under design now and expected to be ready for three years of construction in 2029.
The interchange, part of the original construction of the highway in 1953, carries as many as 100,000 vehicles a day between Downtown Pittsburgh and Pittsburgh International Airport. That’s way more than the original design can handle, leading to some of the worst backups in the country between the Fort Pitt Tunnel and the Interstate 79 interchange.
At Green Tree, traffic backs up at the side-by-side loop ramps for exiting and entering the highway at Greentree Road. This creates dangerous conditions because motorists come together trying to get on and off the highway in the same general area headed outbound.
In a recent five-year period, there were 499 crashes with 249 injuries in the area around the interchange, 2.8 times more accidents than other areas. About 76% of those were rear-end crashes.
During peak travel times, that pinch point also causes traffic to back up on neighborhood streets such as Greentree Road, Mansfield Avenue and Poplar Street, which currently don’t have turning lanes or capacity to release traffic onto the highway.
Anthony Annett, PennDOT’s project engineer, said the main goal is to separate those ramps so they use different exit and entrance points. That will include major changes of those local roads to handle extra traffic in different areas.
For example, outbound traffic from Pittsburgh exiting at Green Tree will make a direct exit onto Greentree Road at a new intersection with a traffic light at Mansfield. Greentree Road and Mansfield will be widened with additional lanes in that area.
Another change in that area will be the relocation of the Greentree Road bridge over the Parkway West to meet the new intersection with a wider bridge.
Since there will no longer be a loop ramp for motorists to head outbound from Greentree Road, all outbound traffic will use a widened ramp from Poplar Street. That ramp will become a longer, two-lane ramp so motorists can merge safely onto the highway toward the airport.
There also will be major changes on the inbound side of the highway.
The exit ramp to Greentree Road will be moved back to start near the Wheeling & Lake Erie Railway bridge and cross above Poplar Street. Additionally, a new slip ramp will be installed off the main ramp to allow motorists to exit at Poplar Street.
Annett said the goal of the slip ramp is to take some of the traffic off Greentree Road for drivers who don’t need to go that far. Several residents raised major concerns that others who should use Greentree Road will use the slip ramp and turn right to use residential streets as a shortcut.
PennDOT District Executive Jason Zang told residents the agency will look at making a right turn illegal or monitor traffic once the project is completed to deal with that if it becomes a problem.
The project also will include a nearly mile-long, decorative sound barrier along the inbound highway around Parkedge Road to reduce noise. New, wider sidewalks will be added along Greentree Road to improve access to Green Tree Park.
Annett said the project will have minor environmental impacts and will need small pieces of unused land in Green Tree and Wilson parks plus “slivers” of some properties, but none of them will ruin the use of the property.
Green Tree Mayor Ed Schenck said in an interview after the meeting he has some concerns about traffic from the slip ramp onto Poplar Street, but he generally supports the concept of the redesign. The wider bridge on Greentree Road and ramp improvements should be positive for the borough, he said.
“I think it’s a good project overall,” he said. “It’s going to be disruptive for 2½ years, but everything takes time.”
Ed covers transportation at the Pittsburgh Post-Gazette, but he's currently on strike. Email him at eblazina@unionprogress.com.