A century-old stone arch bridge in Penn Forest Township is closed because its foundation has shifted several inches and its mortar is crumbling.

A study is planned for the span, after which Carbon County engineers and commissioners will be faced with deciding whether to close the bridge permanently, repair it or replace it.

The bridge, which spans Stony Creek, was last inspected on March 16, said county Commissioner William O'Gurek. That inspection alerted the state Department of Transportation to the urgent need to take immediate action.

He said repairing the bridge could cost about $225,000, and about twice that to replace it.

"It's getting expensive out there. We own 19 bridges," said commissioners Chairman Wayne Nothstein. "A lot of them are deteriorating, and we have a lot of work to do on them."

O'Gurek referred to engineer Ron Tirpak's report, which outlines steps needed to repair the span.

Nothstein also said that if replaced, the new span would have to meet federal standards – a costly endeavor.

The 24-foot-long, 16-foot-wide span on Stony Creek Road, west of Route 903, was built in 1910, has a five-ton weight restriction and carries about 20 vehicles a day. An April, 2011 report by Ronald and Michael Tirpak of Carbon Engineering, Summit Hill, describes its condition as poor. The pavement across the bridge is worn and cracked, rain leaks through the deteriorated seal along the parapet walls, and the deck is sinking, preventing proper drainage.

Stones are cracked, stones are falling out and about 75 percent of the mortar is gone.

There is an alternate route, Nothstein said.

"There is another bridge," he said. "I spoke to one of the residents ... for him, it's going to be about two, two-and-a-half miles."

Once the engineer delivers his report, the state Department of Transportation decides how critical the need for repairs or replacement is, and how quickly the fixes must be done," O'Gurek said.