Thousands of Illinois bridges are structurally deficient, according to data from the Federal Highway Administration, but that doesn’t mean they’re necessarily unsafe.
Illinois ranks 26 out of 50 states, Puerto Rico and the District of Columbia, in terms of the percentage of structurally deficient bridges, according to FHA data compiled in 2016.
About 2,200 out of 26,700 bridges meet the qualifications for structural deficiency in Illinois. Structural deficiency is based on a rating of numerous bridge conditions, including the quality of the bridge’s deck, structure, waterway adequacy, and other things.
Still, “just because 2,243 bridges are structurally deficient in Illinois, that doesn’t mean the bridges are unsafe for public travel,” said Nancy Singer, a public affairs specialist with the Federal Highway Administration.
“If it’s unsafe, it’s closed,” she wrote in an email.
Kelsea Gurski, a spokeswoman for the Illinois Department of Transportation, echoed Singer’s comments.
“A structurally deficient rating means there are elements of the bridge that need to be monitored, inspected and maintained on a more frequent basis,” she wrote in an email. “If any unsafe conditions are identified, the structure is repaired or closed.”
About 8.4 percent of all Illinois bridges are considered structurally deficient by the FHA. Considered as a measurement of the total area of bridges, however, that number inches up to 10.4 percent.
Within Illinois, Cass County has the highest portion of structurally deficient bridges, at 36.3 percent by area. Monroe County has the lowest number, at 0.4 percent.
St. Clair and Madison Counties rank 92nd and 35th, respectively, out of Illinois’s 102 counties, in terms of the total area of bridges that are structurally deficient. About 17.7 percent of St. Clair County bridges are structurally deficient, but only 5.2 percent of Madison County bridges share the same quality.
Cook County has the most structurally deficient bridges, at 160, and their average age is 70.9 years old. Peoria County has the second most structurally deficient bridges, at 74, and their average age is 58.8 years old. Monroe County ties with two other counties for the lowest number of structurally deficient bridges, at just two, and their average age is 91.5 years.
To some groups, like the American Road & Transportation Builders Association, the numbers on structural deficiency need attention.
“Investing in this part of our highway and bridge network would help support economic growth,” wrote Alison Premo Black, the organization’s chief economist, in an email.
Gurski, with IDOT, wrote that “over the next five years, IDOT anticipates spending nearly $2 billion to replace or rehabilitate approximately 500 bridges.”
Additionally, the number of structurally deficient bridges has actually gone down over the past five years, from 67,000 nationwide to 56,000, according to Singer, with the FHA.
At the same time, she explained, more bridges have been built, so the percentage of those that are structurally deficient has been getting smaller.
“(The) numbers are going in the right direction,” she said.