State restricts use of bridges in bad repair
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The Pennsylvania Department of Transportation has put traffic or weight restrictions on 21 old bridges in four counties because of advanced deterioration, a new development in the state's bridge crisis.
The two-lane bridges, built so long ago that engineering plans for them don't exist, are in Westmoreland, Washington, Fayette and Greene counties, which constitute PennDOT District 12.
There is potential for the problem to be more widespread, because PennDOT owns about 2,000 more of the same type of reinforced concrete T-beam bridges in the state's other 63 counties, where special inspections still are under way. Of those spans, 898 already are rated "structurally deficient," meaning they're badly deteriorated and in need of major repairs.
"We're kind of at the forefront" of the accelerated bridge inspection effort, District 12 engineer Joe Szczur said last week. The haste was prompted after a beam of a differently engineered overpass collapsed onto Interstate 70 in Washington County in December. The incident prompted a statewide review of all concrete box-beam bridges, many of which have been closed, weight-restricted or lane-restricted.
"The I-70 incident surprised everyone," Mr. Szczur said. "We learned from the investigation and asked ourselves what else may be at risk. That's when we started looking into these T-beam bridges built in the early 1900s. We've been finding out more about how they were built, how they're deteriorating and how they're performing."
PennDOT engineers identified and did special inspections on 163 of the bridges whose average age is 71 years. They then determined that 21 were bad enough to warrant closing the shoulders, imposing weight limits or restricting them to an alternating single lane of traffic.
Some are on busy routes, like Route 88 north of Monongahela, Route 366 near New Kensington and Route 1009 in the Cecil village of Cool Valley, just off I-79.
While it is not yet weight-restricted, the shoulders have been closed on the bridge carrying Route 88 over Mingo Creek in Carroll Township. The heavily traveled road between Monongahela and Finleyville is the route that Mid-Mon Valley Transit buses use for Pittsburgh service.
A 10-ton weight limit has been imposed on the span carrying Route 366 over Pucketa Creek, used by 9,600 vehicles on an average weekday, many of them big trucks. A detour was being planned.
The shoulders also have been closed on the short Route 1009 bridge over McPherson Creek, with average daily ridership of 8,700, many of them people who live in new suburban housing developments in Cecil and Peters.
"We have tailored the restrictions to the condition of each bridge," Mr. Szczur said. "We've also prioritized them in order to try to line up plans and money for replacement."
Because PennDOT has not had a major revenue boost since 1997, and because energy, concrete and steel prices have brought record inflation to the construction industry, PennDOT's backlog of deteriorated bridges has grown. The department owns and maintains about 25,000 bridges statewide.
"Over the years, from one [biennial] inspection cycle to another, we noted the increased deterioration," Mr. Szczur said, "but we had no methodology to analyze and rate these bridges. In most cases, they're pretty sturdy, a testimony to why they have lasted so long."
But time has taken a toll, he said, "and because we're not certain if the bridges will hold up, we're taking precautions now. We don't want to see another bridge sag or break or endanger people."
The reinforced concrete T-beam bridges that now have PennDOT's attention are T-shaped, with the bridge deck constituting the top of the T. The beams contain about 1-inch round or square reinforcing rods, encased in concrete. The steel rusts, expands and causes the concrete to crack and fall.
The beams were poured in lines, and then a concrete deck was poured on top of them, somewhat akin to nailing sheets of plywood to floor and roof joists in house construction.
"They were very solid structures but they've served their useful lives," Mr. Szczur said.
Here's a list of bridges PennDOT has restricted:
Washington County -- Route 88 over Mingo Creek, Carroll; Route 1009 over McPherson Creek, Cecil.
Westmoreland County -- Route 201 over Pollock Run, Rostraver; Route 366 over Pucketa Creek, Lower Burrell; Route 819 over Slate Creek, Hempfield; Route 981 over Barron Run, South Huntingdon; Route 982 over Welty Run, Mount Pleasant Township; Route 1006 over Freeman Run, Fairfield; Route 3071 over Little Sewickley Creek, Arona; Route 4003 over Brush Creek branch, Penn-Hempfield township line; Route 4010 over Brush Creek, Penn; and Route 4041 over Turtle Creek, Murrysville.
Fayette County -- Route 166 over Dunlap Creek, Luzerne-Redstone line; Route 381 over Mill Run, Springfield; Route 857 over Georges Creek branch, Georges; Route 1031 over Galley Run, Connellsville-Upper Tyrone line; Route 4046 over Lutz Run, Washington Township.
Greene County -- Route 18 over Bates Fork, Washington Township; Route 18 over Browns Creek branch, Morris; Route 21 over South Fork 10-Mile Creek, Center; Route 218 over Roberts Run, Wayne.
First Published October 16, 2006 12:00 am
