Jane Byrne Interchange construction almost complete

CHICAGO(CBS)-- After nine years of construction, construction on the Jane Byrne Interchange is almost finished. 

The interchange connects three Chicago expressways. State officials held a formal ribbon cutting Wednesday morning to celebrate.

"No one likes construction delays, but brighter days are ahead in the next few days as we declare this project substantially complete," said Illinois Department of Transportation (IDOT) Secretary Omer Osman.

CBS 2 has been tracking the slow progress for years. 

IDOT broke ground on the 35-part improvement project in 2013. It was originally expected to cost $535.5 million and to be finished in 2018, but the project quickly was set back by delays and cost overruns. The latest cost estimate for the project was $806.4 million.

The last of the major ramp closures will reopen as soon as Friday, or as late as Monday, according to IDOT.

CBS 2 was told overnight lane closures may still pop up in the future for smaller issues like painting of bridges, landscaping, or work on lighting or paving. But IDOT said that work will be done overnight, and should not impact daytime traffic.

State officials expect the finished project to reduce traffic delays by half.  

"We anticipate a 50% reduction in delays for all vehicles over the course of a day. Five million hours fewer of drivers sitting in congested traffic. Savings of $185 million in lost production from delayed travelers each year. Decreased idle time resulting in saving 1.6 million gallons of gasoline annually. And a one-third reduction in greenhouse gases. Twenty-five percent fewer crashes for motorists. And thousands of jobs created," Gov. JB Pritzker said.

That's welcome news after nine years of braking and merging, lane shifts and ramp closures for drivers with the hopes of unclogging a system that was designed in the 1950's. IDOT even called it "one of the worst bottlenecks in the country."