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Problems noted on stretch of pike that just opened

Thursday, September 05, 2002

By Joe Grata, Post-Gazette Staff Writer

The Pennsylvania Turnpike Commission is investigating problems with earthen fill on a 17-mile section of the Mon-Fayette Expressway between Interstate 70 in Fallowfield and Route 51 in Jefferson Hills, a stretch that has been open for less than five months.

The right northbound lane was closed yesterday just south of the Finleyville-Elrama interchange so a geotechnical engineering crew could install equipment to monitor subsidence and land movement.

The turnpike commission, owner of the toll road, said minor changes have occurred in a 150-foot-high embankment on which the divided four-lane highway sits. It is part of a section, opened April 12, that was built mainly on bridges, excavated cuts and earthen fill to span valleys and cut through the hills of southern Allegheny and Washington counties.

"Some settlement is occurring," commission spokesman Joe Agnello confirmed. "We hope the whole embankment isn't moving."

To find out, the turnpike commission hired an engineering firm to drill about 125 feet into the embankment to install an inclinometer, a device that measures and pinpoints the specific area of land subsidence or other movement.

HDR Engineering Inc. of Pittsburgh is doing the testing and drilling, which to date has cost about $100,000.

The same firm installed six of the devices near the Allegheny-Washington county line more than a year ago to monitor an area where the surface subsided about 15 inches. Before the expressway opened, a 400-foot section of concrete pavement was ripped out and replaced with asphalt.

"Settlement like this is fairly common on expressways built on fill and large embankments," Agnello said. "We don't regard it as anything major."

Since Interstate 279 was built from Pittsburgh through the North Hills in the 1980s -- the most recent comparable expressway project in the region -- the Pennsylvania Department of Transportation has been forced to return a half-dozen times to stabilize embankments, landfill and retaining walls.

Agnello called it coincidental that New Enterprise Stone & Lime Co. of Bedford County was the contractor on two separate areas with embankment problems.

The firm received $68.5 million for its work.

The lane south of the Finleyville-Elrama interchange is to be closed daily for about two weeks while the earth-monitoring equipment is installed.

Traffic should not be a problem. Turnpike commission officials said an average of 8,107 vehicles a day used the newest 17-mile section of the expressway in July, the latest month for which statistics were available.

Joe Grata can be reached at jgrata@post-gazette.com or 412-263-1985.