State transportation officials have placed about 60 Wisconsin bridges in danger categories that indicate the structures have designs that make them more vulnerable to failure and are deteriorating.
An Associated Press review of the latest records in the National Bridge Inventory found some 7,795 bridges across the country have been classified as both "fracture critical" and "structurally deficient," a combination of red flags that experts say is particularly problematic.
A fracture critical designation means the bridge or part of it could collapse if a single vital component, such as one load-bearing girder, fails. Structurally deficient means at least one major component has deteriorated and the bridge needs repairs to remain in service and will eventually need major rehabilitation work to address the deficiency.
Classification in both categories doesn't mean the bridges could fall at any moment. But it does signal the bridges are more susceptible to collapse and need repair. The Interstate 5 bridge that collapsed in Washington in May was classified fracture critical. The Interstate 35W bridge that fell in Minneapolis in 2007, killing 13 people, was classified as structurally deficient, although that collapse was linked to a too-thin gusset plate, a fracture critical component.
State Department of Transportation Structures Bureau Director Scot Becker downplayed the classifications, insisting Wisconsin's bridges are safe. The fracture critical term may sound ominous, but it simply signals the rest of the bridge wasn't designed to carry the load if one part fails, he said. A new bridge, for example, could be in fracture critical status the day it opens, he said. The degree of deterioration that puts a bridge in the structurally deficient category can vary, he added, from rust on the bridge's decking to pot holes.
If inspectors deem a bridge is unsafe, he said, the DOT typically places weight limits on the structure or closes it.
The number of bridges that fit both categories nationally has been fairly constant for a number of years, experts say. But the lists fluctuate frequently; repairs can move a bridge out of the deficient categories while spans that grow more dilapidated can land on the lists. There are occasional data-entry errors as well as considerable lag time between when state transportation officials report data to the federal government and when updates are made to the federal government and when updates are made to the National Bridge Inventory. Since the federal inventory relies on information from state transportation departments, state officials have the latest records.
Wisconsin has 14,022 bridges at least 20 feet long, the cutoff for federal recognition as a bridge. The AP review identified 60 Wisconsin bridges in both categories.
Becker said 10 of those bridges have been repaired. An additional 18 have been slated for repairs between now and 2017. Another three have been closed. He said two bridges were incorrectly included on the list but didn't know why.
The DOT has no plans to repair 27 bridges in both categories. Most of those bridges are small spans in largely rural areas. The list does include at least two bridges in Milwaukee, however, as well as the Blatnik Bridge, which links Superior with Duluth, Minn. Wisconsin and Minnesota transportation inspectors conduct joint reviews of the bridge, but the Minnesota DOT is responsible for initiating repair projects. The bridge linking Houlton to Stillwater, Minn., also stands in both categories. Minnesota and Wisconsin transportation officials are currently building a new bridge to replace it.
Wisconsin inspectors placed an additional bridge in the countryside northeast of Antigo in both fractural critical and structurally deficient status in May, four months after the federal data was finalized. The DOT has plans to repair the bridge, but the agency is still reviewing the span's condition and the need for work.
Wisconsin lawmakers have been grappling with how to pay for highway work for years as revenue from the state gas tax and vehicle registration fees shrinks. The state budget Gov. Scott Walker signed in June left the state's $32.8 million local bridge assistance program, which funds 80 percent of repairs on municipal bridges, untouched. But it cut $51 million from the state highway rehabilitation program, which funds highway and interstate repairs, including bridge work, over the next two fiscal years.
Becker said there simply isn't enough money to go around, forcing state and local agencies to prioritize repairs according to traffic volume. Many of the bridges not slated for repairs are in rural areas and see very little traffic each day, making them low priorities, he said.
"There's a bigger list of needs than what the funding is," Becker said. "That's the ultimate problem."