Recommendations Constructed by IDOT in the Fall of 2009
CBB conducted a study for the Illinois Department of Transportation (IDOT) to improve the safety of the Martin Luther King (MLK) Bridge over the Mississippi River. The goal was to reduce the historically high number of fatal crashes on the bridge while maintaining acceptable traffic flow. The MLK Bridge carries 37,500 vehicles per day and previously had four narrow travel lanes (approximately 10 feet in width) with no median barrier to separate opposing traffic flows.
A rash of fatal crashes prompted IDOT to investigate ways to provide a raised median between the opposing traffic lanes on the bridge. CBB developed a range of lane reconfiguration alternatives and evaluated them with a robust VISSIM model. The VISSIM model includes both the MLK and PSB Bridges which together act as a system to carry interstate 55/70/64 traffic over the Mississippi River and connect these freeways to East St Louis and downtown St. Louis. The study recommended eliminating a westbound lane over the bridge to allow for three 12 foot lanes and a median barrier. This configuration was constructed by IDOT in the fall of 2009.