The Pennsylvania Department of Transportation knows something must be done to improve the deteriorating condition of the Parkway East bridge over Four Mile Run, between the Squirrel Hill Tunnel and the Oakland interchange.

But the project is so complicated and the work area so tight that the agency won’t decide until at least the middle of next year whether to replace the existing bridge or rehabilitate the structure.

PennDOT and a representative of consultant McCormick Taylor met for the first time Wednesday evening with residents of the lower Greenfield neighborhood known as “the Run” to discuss construction options. The 1,015-foot bridge is listed in fair condition, but parts of the deck have started to fall off, and the agency has closed a small park under the bridge until crews can replace safety shields later this month.

Any serious change in the bridge’s condition would lead to a weight limit, which would create a serious traffic problem for the 9,000 trucks that use it every day.

Doug Seeley, PennDOT’s assistant district executive, told residents in a meeting at Greenfield Elementary School the project is in the “very early stages” and construction won’t begin until at least 2028. Because of the nature of the project, he said, it’s important for the agency to hear ideas and concerns from residents before engineers decide how to upgrade the span built in 1951.

“We want to get your feedback related to this project,” Seeley said. “That’s why we’re here.”

Here are the factors that make this such a daunting project for engineers: The bridge is located on an interstate highway that carries 120,000 vehicles every day above a residential neighborhood, recreational area, railroad tracks, popular trails, and other roads and bridges. The goal is to maintain traffic as much as possible on the highway with the least amount of disruption to the neighborhood underneath.

Another complicating factor is that PennDOT and Pittsburgh have at least 10 other major projects in the area in the next half-dozen years, including redesigning the Squirrel Hill and Bates Street interchanges.

Faced with the same traffic concerns at the Commercial Street Bridge on the other side of the Squirrel Hill Tunnel, PennDOT decided to replace that bridge by building a replacement adjacent to it, then closing the highway for 25 days in 2026 to demolish the old bridge and slide the new bridge into place. There, though, the bridge is above Frick Park with only one road, Commercial Street, and a trail under it, so crews moved those facilities 150 feet out of the way last month until the project is finished.

At Four Mile Run, officials don’t know whether there’s enough room to build the replacement close by. If there is, the project likely would involve PennDOT buying some of the dozens of homes and businesses nearby to create a staging area to build the new structure.

Other options include shifting all traffic to one side of the bridge while rehabbing or replacing the other half or building temporary lanes on either side of the existing bridge to carry traffic during construction.

“It’s going to be a challenge, for sure,” Seeley said after the presentation. “We’re not sure what we’re going to do yet.”

Although it could change, the potential area affected by construction now extends to Saline Street between Frazier and Whitaker streets on one side of the valley under the bridge and Boundary and Naylor streets on the other side.

Matt Wille, owner of Stratosphere Inc. musical instrument store on Boundary Street, is hoping PennDOT decides to rehab the bridge. With his business only about 40 feet from a bridge support, he and his five employees likely would have to move if there is a replacement.

“I’m really hoping rehabilitation will be enough,” he said. “With the real estate prices as high as they are, I really don’t want to move. We’re literally right across from the bridge [support].”

Other residents raised concerns about construction noise, disruption to popular Junction Trail and whether the bridge work would cause additional flooding in the neighborhood. PennDOT will do all it can to control water runoff and mitigate noise from the highway, officials said, but the agency won’t know until it chooses the construction method how it will handle construction noise or how much it will interfere with trail traffic.

Seeley said PennDOT and the consultants will hold additional neighborhood meetings after it picks a construction method. Residents were asked to fill out surveys with the comments and concerns and have at least 30 days to submit them.

Comments also may be sent to PennDOT project manager Cheryl Solosky at csolosky@pa.gov.

Ed Blazina

Ed covers transportation at the Pittsburgh Post-Gazette, but he's currently on strike. Email him at eblazina@unionprogress.com.

Ed Blazina

Ed covers transportation at the Pittsburgh Post-Gazette, but he's currently on strike. Email him at eblazina@unionprogress.com.