Illinois officials will begin engineering studies for reconstructing the "Circle Interchange," located west of Chicago's Loop.
The point at which the Kennedy, Dan Ryan and Eisenhower expressways and the Congress Parkway converge has been labeled the nation's top traffic bottleneck.
Gov. Pat Quinn said Monday the $40 million, two-year study will identify needed improvements, cost and construction schedule.
Quinn's Transportation Department wants suggestions from taxpayers in nearby neighborhoods and businesses, Chicago city officials, the Chicago Transit Authority and the University of Illinois at Chicago.
The interchange has not been improved in its 50-year history. It handles 300,000 vehicles daily -- 26,000 trucks -- which travel at below ideal speeds for more than 14 hours a day.
Preliminary analysis calls for additional lanes on key ramps.