CHICAGO — From major spans over the Mississippi River to overpasses on traffic-choked arteries skirting Chicago, some 200 bridges throughout Illinois are in need of replacement or repair because of their outdated, insufficient design and their advanced deterioration.
That particular combination of red flags has emerged as a vexing problem around the country, as bridges are pushed beyond their expected lifespans and assaulted by ever-increasing traffic loads.
In Illinois, with too little money to throw at the problem, state transportation officials have gone into triage mode, prioritizing the busiest bridges in the worst shape for overhaul, implementing weight limits or closure orders on others, and closely monitoring the rest.
“For a bridge to fall into both of those categories it is — how should I put it? — it should be a wakeup call,” said Keith Brandau, a Champaign-based structural engineer for the firm Fehr Graham who has helped inspect bridges for local governments in Illinois.
An Associated Press review of national bridge records found that some 7,795 bridges nationwide are classed as both “fracture critical” and “structurally deficient,” a combination that experts say is especially problematic.
The first designation refers to bridges that were designed with no redundant protections, putting them at risk of collapse if a single, vital component fails. The “structurally deficient” label is attached to bridges that need rehabilitation or replacement because at least one major component has advanced deterioration or other problems that have led inspectors to deem its condition “poor” or worse.
The most recent federal data available identifies 189 such bridges scattered around Illinois. Pinning down an up-to-date figure is difficult, because the numbers fluctuate as bridge improvements and repairs are made to some structures while others deteriorate and slip into disrepair.
“We don’t feel that the public should be worried,” said Carl Puzey, chief of Illinois’ Bureau of Bridges and Structures, which subjects fracture critical bridges to a more intensive inspections regime than the rest of the state’s roughly 26,000 bridges.