A Pennsylvania Turnpike bridge scheduled for demolition next month could play a key role in developing a riverfront park that would serve all of Allegheny County, Dave Fawcett says. The bridge spans the Allegheny River at Harmar and Plum.

The former county councilman has persuaded the current council to ask the Turnpike Commission to delay destruction for 90 days of the now unused Allegheny River Bridge.

Carl DeFebo, media and public relations manager for the commission, said the state-affiliated agency was considering the county's request.

Saving the bridge would be an investment in the county's future, Mr. Fawcett said.

"It would be a tragedy to blow up a bridge that could serve [someday] as a trail connector," he said. "It would cost tens of millions of dollars to replace its piers alone."

The three-month reprieve would allow time for an engineering study to determine whether the piers and the lower portions of the bridge's steel structure could be adapted for a bicycle and pedestrian bridge.

A smaller bridge across the Allegheny could link future parks or trails in Harmar and Plum, Mr. Fawcett said. In that regard, the pedestrian bridge could be a critical link in a long-planned riverfront park, he said.

Mr. Fawcett, a Republican from Oakmont, was one of the original members of County Council. In 2006, he and Councilman Jim Burn, D-Millvale, drew up legislation that proposed development of a riverfront park that eventually would be 150 miles long and touch at least 66 municipalities.

As envisioned by County Council, it would it would be composed of strips of land along one bank or the other of the four major rivers that pass through the county. The measure passed unanimously.

Completed in 1951, the Allegheny River bridge is almost 2,200 feet long. It had room for four lanes of traffic. Its replacement is a new double span that cost $190 million.

Turnpike traffic already has been diverted to one of the two new parallel bridges. Decking and some of the steel trusses have been removed from the older span in recent weeks.

That preparatory work would not interfere with efforts to convert the bridge to other uses, Mr. Fawcett said. The piers appear sound, and a new roadway probably could be installed on the lower portions of the existing steel structure, he said.

Rights of way would have to be negotiated with railroads on both sides of the river before any trails could be developed. A park on the south, or Plum side of the Allegheny River, for example, could be part of a future biking and hiking trail that could run from Pittsburgh's Strip District to New Kensington and Arnold in Westmoreland County, Mr. Fawcett said.

The former Turnpike bridge also would provide a link to communities and trails along the north, or Harmar side, of the river.

A spokeswoman for Allegheny County Executive Dan Onorato said he supported council's action in seeking a delay in the bridge demolition.

"It certainly would be beneficial for trail users to be able to cross the river," Megan Dardanell said. "Converting the old bridge would be one solution, and it is definitely worth exploring."

Demolition with explosives of the bridge's steel frame -- "dropping the truss" -- is scheduled tentatively for July 13, said Tom Fox, public information manager for the Turnpike Commission's western regional office.

"This question isn't as simple as it seems," he said. When the commission received approval to build its new bridges, it agreed to remove the old bridge, including the piers, from the river, he said.

If the county wants to take over and maintain the bridge, it would need approvals from multiple agencies, including the Army Corps of Engineers, the state Fish and Boat Commission and state Department of Environmental Protection, Mr. Fox said.

"I don't know how much of the bridge is left to save," he said. "Most of the horse is out of the barn."

Looking for more from the Post-Gazette? Join PG+, our members-only web site. You'll get exclusive sports content, opinion, financial information, discounts from retailers and restaurants, and more. Our introduction to PG+ gives you all the details.