Repairs to Port Authority bridge likely to take up to 3 months, cost $2M

Repairs to Port Authority of Allegheny County’s bridge over Saw Mill Run Boulevard in Pittsburgh could take up to three months and cost more than $2 million, transit officials said Wednesday.

An engineer discovered part of the bridge structure had shifted earlier this month, causing an “abnormally large gap” at a joint on the bridge deck.

A Port Authority spokesman said last week that water coupled with the freeze and thaw cycle likely caused the span to shift. Water penetrated part of the concrete support structure and then expanded when temperatures dipped below freezing.

To fix the 600,000-pound bridge, it must be lifted back into position while contractors also replace bearings and anchor bolts. Engineers had to remove pieces of the bridge deck to gain access to certain parts of the bridge, which also will be replaced.

The 1,052-foot bridge carries buses and Red Line light-rail cars over Route 51. It has been closed since Feb. 4, forcing Red Line trains to use the Blue Line. A rail shuttle is operating between Overbrook Junction and Potomac Station, and a shuttle bus is running from Potomac Station to Station Square. Both run every 20 to 30 minutes, and neither is collecting fares.

The discovery of the shifted bridge came just days after the Fern Hollow Bridge that carries Forbes Avenue over Frick Park collapsed, sending a Port Authority bus and five vehicles more than 100 feet into a ravine.

The cause of the Frick Park bridge collapse remains under investigation, city officials said. Investigators from the National Transportation Safety Board said their investigation could take 12 to 18 months or longer.

The collapse put a renewed focus on the condition of bridges across the county and state.

In all, Allegheny County has about 175 bridges — state- and locally owned — that are rated in “poor” condition, according to PennDOT records. In Westmoreland County, that number is about 140.

Last week, McKeesport Mayor Michael Cherepko shut down the Versailles Avenue Bridge because of safety concerns as temperatures see-sawed above and below freezing, putting the already unsound bridge at further risk.