Lake Saint Louis Boulevard Roundabout

Why is this project needed?  

The City of Lake St. Louis experienced increasing congestion and delays on the south side of the Lake St. Louis Boulevard interchange with I-70, specifically at the two closely spaced signalized intersections on Lake St. Louis Boulevard, the eastbound I-70 ramps, and Veterans Memorial Parkway.  According to the 2016 Roundabout Study, the analysis shows an expected 70 percent reduction in injury crashes by installing the roundabout. 

Peak delays will be reduced from 45 seconds per vehicle to about 5 seconds per vehicle. That is an 800 percent reduction in delays. 

What exactly is being done?

The City of Lake Saint Louis completed a study to evaluate two potential roundabout configurations that would help alleviate the traffic flow issues being experienced.  One option consisted of two closely spaced "4-legged" smaller diameter roundabout. Another option was a larger diameter "6-legged" roundabout configuration that incorporates all entries of the two existing intersections into one roundabout.  Both roundabout options were found to be feasible and each would provide significant operational improvements to the intersections, with a significant reduction in delay and improvement in Level of Service.

The preferred option is the 6-legged roundabout you can see here. 

This option was selected solves the lane merging issue, decreased cost, and fewer property impacts.

Summary of Study and Preferred Alternative Information 

What are the anticipated construction impacts? 

Information regarding the updated timeline and construction impacts will be disclosed prior to the start of construction. 

How much will this project cost? 

This project is a MoDOT Cost Share project between MoDOT and the City of Lake St. Louis. Funding is provided by the City of Lake Saint Louis Capital Sales Tax, Federal Surface Transportation Program, St. Charles County Road Board, and MoDOT Cost Share. The construction award amount is approximately $3 million. 

Lake Saint Louis Boulevard Roundabout Press Releases

MO Highways and Transportation Commission awards Lake St. Louis Boulevard/I-70 roundabout project

MoDOT to close Veterans Memorial Parkway near Lake Saint Louis Boulevard for roundabout construction

If I have questions, who can I contact?

Please direct questions to MoDOT's St. Charles County Area Engineer Andy Tuerck at Andy.Tuerck@modot.mo.gov.