Pa. Turnpike considers plans to replace Allegheny Tunnels in Somerset County
December 24, 2014 12:02 AM
The first Allegheny Tunnel, which currently carries westbound traffic, was built in the late 1930s and the second opened in 1965.
By Jon Schmitz / Pittsburgh Post-Gazette
The Pennsylvania Turnpike has revived plans to replace the Allegheny Tunnels in Somerset County, a project that has been talked about for nearly two decades.
The turnpike commission is considering six options for abandoning the 6,070-foot-long tunnels, longest on the turnpike mainline. Three would involve building new tunnels and three would carve an open highway through the mountain either to the north or south of the existing tunnels.
Preliminary cost estimates for the “cut” options range from $242 million to $345 million, while estimates for the tunnel options range from $537 million to $694 million, according to turnpike consultant L.R. Kimball. Annual maintenance costs for a tunnel would exceed $3 million, several times what an open highway segment would cost.
Turnpike spokesman Carl DeFebo said the cost differential was just one of several factors the commission will consider in choosing a preferred option, possibly in the spring.
After that, design, acquiring property and securing permits would take four years and construction at least two years, so “in the best case you might be talking about six or seven years” before traffic could be shifted to the new segment, turnpike project manager Jeffrey C. Davis said.
The turnpike commission began studying replacement of the tunnels in 1996 but shelved plans to cut a 220-foot-deep notch in the mountain amid opposition from environmental groups.
The Mountain Field and Stream Club, which owns 1,400 acres above the existing tunnel, again has come out against any plan to carve a highway into the mountain, saying that would be disastrous to the landscape, wildlife, plants and the water supply.
PG graphic: Proposed replacement (Click image for larger version)
George Jugovic, general counsel for PennFuture, which is representing the club, said it has filed public information requests and hired its own expert to review the turnpike’s alternatives.
The group does not accept the turnpike’s cost estimates as accurate, but even if a tunnel is more expensive, it would be worth the cost for “a more environmentally sound, more environmentally sane” outcome, Mr. Jugovic said.
He noted that construction of the final segment of Interstate 99 near State College, which also involved carving into a mountain, cost twice as much as originally anticipated after the excavation unearthed highly toxic pyrite rock.
The first Allegheny Tunnel, which currently carries westbound traffic, was built in the late 1930s and the second opened in 1965. The tunnels are about 13 miles east of the Somerset interchange and 23 miles west of Bedford.
In 1981, the turnpike commission completed a third lane on the westbound approach to the tunnel to serve as a truck climbing lane to ease congestion, and in 1996 changed the merge pattern so trucks could remain in the right lane entering the tunnel. Some of the S-curves to the east of the tunnels were straightened in a reconstruction project that was completed in 2008.
The tunnels underwent major rehabilitation in 1987 and 1988 and an inspection in 1995 and 1996 found rapid deterioration, prompting the first plan for a tunnel bypass.
Mr. DeFebo said the existing tunnels need to be replaced because of their age, traffic congestion and crashes. “Two lanes in each direction is not enough capacity,” he said.
On the Sunday after Thanksgiving, eastbound traffic was backed up eight to 12 miles from the tunnel entrance for about eight hours, he said.
Widening the existing tunnels would disrupt traffic for at least five years and pose safety hazards to travelers and construction workers and “is not an option,” Mr. DeFebo said.
Other reasons that turnpike officials opted for the “cut” option in 1996: Having a tunnel requires hazardous materials trucks to exit the turnpike and use alternate routes for the 36 miles between Somerset and Bedford. The tunnels must be temporarily closed several times a year so workers can remove giant icicles that form on the walls.
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