Cass Street bridge repairs in downtown Joliet will take more than a year as the state replaces a deteriorated steel deck that has limited traffic for nine years.

More work will be done on the bridge, which was shut down entirely last week for repairs.

The replacement of steel that provides the road surface for vehicles that cross the Des Plaines River is the primary reason the project will take more than a year, an official with the Illinois Department of Transportation said.

The bridge is scheduled to be closed until late 2026.

“The structural steel repair is the main element of the job,” Jon Schumacher, bureau chief for IDOT District One, said in an interview this week.

IDOT identified deteriorated steel as an issue in 2016 when it limited the weight of vehicles that can cross the bridge.

Two of the three lanes on the bridge had already been shut down for more than a year, as traffic was limited to the side of the bridge where the steel is in good shape.

The repair project scheduled for the next year is expected to return the bridge to normal traffic with no load limits, Schumacher said.

None of the Joliet drawbridges, all built in the 1930s, has required the fundamental reconstruction of the bridge deck that is planned for the Cass Street bridge.

When the repair project is done, Cass Street bridge traffic will return to normal use, Schumacher said.

“These are some very old structures,” Schumacher said. “We’re approaching 100 years old.”

The Cass Street bridge is one of five downtown drawbridges over the Des Plaines River. A sixth bridge, located at Brandon Road on the city’s outskirts, has been shut down for months for mechanical repairs.

Mechanical repairs for the movable bridges often require the fabrication of custom-made parts, a process that can take months.

But it’s the sheer replacement of the steel bridge structure that will prolong the repair process for the Cass Street bridge, Schumacher said.

The Cass Street bridge project is estimated to cost nearly $23 million.

Replacing the entire steel deck would push the cost over $100 million, Schumacher said. But other steel sections of the deck are in good condition, he said.

“The pieces of steel that we’re leaving in place don’t need to be replaced,” he said.

The project also includes electrical upgrades, mechanical repairs and sidewalk improvements.

Impact on local traffic

The Cass Street bridge also carries U.S. Route 30 east through downtown Joliet and across the Des Plaines River.

Its closing marks an interruption of interstate and local traffic.

The Joliet Police Department is watching the impact on traffic.

So far, the closing of the Cass Street bridge has not had a big impact, said Lt. Rich Stygar in the Joliet Police Department Traffic Division.

“I haven’t noticed any major traffic congestion around the rush hour times,” Stygar said.

If congestion develops, Joliet police will develop a plan to address it, Stygar said.

In the meantime, he said, Joliet may be adjusting to getting through downtown with one of the five bridges closed.

The Ruby Street bridge was closed for two months before the Cass Street bridge was shut down.

“I think people just got used to finding alternative routes that work for them,” Stygar said.

IDOT has been closing downtown bridges one at a time for years for maintenance and upgrades aimed at making a remote bridge control system possible. The plan is to close no more than one downtown bridge at a time.