A coalition of road builders, engineering firms and construction industry groups sued Cook County this week claiming officials illegally diverted about $250 million earmarked for roads, bridges and transit to a fund unrelated to transportation.

Shifting those dollars violates a constitutional amendment passed in 2016 that prohibits state and local governments from dipping into taxes and fees that were collected for transportation projects, the lawsuit stated.

A Cook County spokeswoman said the government does not comment on ongoing litigation.

"The county's roads are deteriorating," Illinois Road and Transportation Builders Association CEO Michael Sturino wrote Cook County President Toni Preckwinkle in February before the lawsuit was filed Tuesday. "Nearly half of Cook County's bridges are considered either structurally deficient, functionally obsolete or both."

Yet the county deposited revenues from the gas tax and other transportation-related fees into the public safety fund that pays for the sheriff's and state's attorney's office, among other expenses, the lawsuit said.

The lawsuit charged that the county also does not track the allocation of those revenues and has refused to cooperate with the association's Freedom of Information Act requests.

Along with the Illinois Road and Transportation Builders Association, other plaintiffs in the lawsuit are the Federation of Women Contractors, Illinois Association of Aggregate Producers, Associated General Contractors of Illinois, Illinois Asphalt Pavement Association, Illinois Ready Mixed Concrete Association, Great Lakes Construction Association, American Council of Engineering Companies Illinois Chapter, Chicagoland Associated General Contractors, Underground Contractors Association of Illinois and Illinois Concrete Pipe Association.

Supporters of the constitutional amendment argued in 2016 that state lawmakers had diverted 6.8 billion from the road fund to prop up its operating budgets and left the region's highways and infrastructure to deteriorate.