Could it happen here? That's the question of the hour following Wednesday night's bridge collapse in Minnesota.
Could it happen here? That's the question of the hour following Wednesday night's bridge collapse in Minnesota.
Three aging bridges across the Delaware River link Burlington County with Pennsylvania. What are the conditions of those bridges?
The federal rating system for bridges is based on a scale of 0 to 100. Bridges that carry a rating of 50 or lower are classified by the Federal Highway Administration as “structurally deficient.”
Structurally deficient bridges aren't shut down, but the agencies that operate them are encouraged to repair or replace those bridges. Federal funds are made available for any bridge with a structurally deficient ranking.
The three bridges that span the Delaware River in Burlington County were rated in December 2006 by the federal government:
The 51-year-old New Jersey Turnpike Bridge in Burlington Township received the highest sufficiency rating at 75.
The Burlington-Bristol Bridge received a 30.1 sufficiency rating, which puts it in the structurally deficient category. The bridge is operated by the Burlington County Bridge Commission. It was built in 1931 and reconstructed in 1996.
The Tacony-Palmyra Bridge, also operated by the bridge commission, was rated at 34.1, also in the structurally deficient category. The bridge was built in 1929 and reconstructed in 1998.
By comparison, the U.S. Interstate 35 West Bridge that collapsed Wednesday into the Mississippi River in Minnesota was rated at 50 and was being repaired in response to that rating.
Bridges in the region operated by the Delaware River Port Authority scored above the federal benchmark. They include the Ben Franklin, Betsy Ross, Commodore Barry and Walt Whitman, according to DRPA officials.
The ratings, however, judge bridges on more than just structural safety, said Dave Lowdermilk, vice president of Pennoni Associates, the firm that conducts annual inspections for the Burlington County Bridge Commission.
There are 116 checkpoints for inspecting a bridge, including lighting, lane width and many other nonstructural factors, Lowdermilk said.
A ranking below 50 doesn't mean a span is in danger of collapsing, he said.
Still, the Burlington County Bridge Commission is in the midst of repair projects at both spans it operates, including a structural upgrade at the Tacony-Palmyra Bridge.
Lowdermilk said he expects both ratings to go up by the next federal report in 2008.
He also said the bridge commission orders annual inspections of its bridges, while federal and state governments require examinations every two years.
“These bridges are maintained unbelievably well,” he said. “The commission does an incredible job of maintaining these bridges.”
The DRPA-operated bridges also are inspected each year, said Bill Brooks, chief engineer for the Delaware River Port Authority.
In addition, the bridge footings are examined every four years by divers, he said.
“We have the utmost confidence in the safety of the (bridges),” Brooks sad.
Any comparison of the DRPA bridges to the one that collapsed in Minnesota would be unfair because the local spans do not share the same design and operate under different traffic and weather conditions, he said.
For example, the I-35 span in Minnesota carried eight lanes across the Mississippi. All DRPA bridges carry fewer than eight, he said.
“It's like comparing apples and oranges,” Brooks said. “Each of these bridges is unique.”
Meanwhile, Gov. Jon S. Corzine yesterday ordered a report on the condition and inspection process of all 6,400 bridges in New Jersey.
About 2,400 of those are under state control. The remaining 4,000 are under federal or local government control.
Corzine said he wants an interim report from the state transportation commissioner in a week and a final report in 45 days.
“If there are any unsafe bridges, they will be shut down,” Corzine said. “Safety comes first.”
The Burlington County Board of Freeholders said yesterday that biennial inspections are conducted on the 364 small and medium bridges maintained by the county.
More information on the safety of those spans is in the process of being compiled and would be released today, county officials said.
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