Interstate 270 Bridge Replacement at Conway Road in St. Louis

What is the problem?

The Interstate 270 bridge over Conway Road has  reached the end of its useful life and needs to be replaced. During the replacement, the bridge over Conway and the bridge over Ladue Road will be widened for both the  northbound and southbound interstates.  To accommodate the wider interstate, the ramps between Interstates 270 and Interstate 64 will be reconfigured.

In addition, the signal at North Outer 40 and Conway will be replaced with a single lane roundabout. Conway under the interstate will be narrowed and lowered.

What are the expected impacts?

All work is going to require narrowed lanes and ramps, as well as shifted lanes.  Both the Conway and Ladue bridge projects will require one lane closed on both northbound and southbound I-270, and the remaining four lanes in each direction will need to be narrowed and shifted. Work on Conway will start on the outside lanes, and then will start on the right lanes on southbound I-270.  As the bridge work completes, the lane closures will move to the middle of the interstate and then to the right lanes on northbound I-270.  Work at Ladue will be somewhat similar, but timing may not allow the traffic shifts on Ladue and Conway to happen at the same time.  The two bridges are far enough apart that traffic will be able to make the necessary shifts during the construction. During the work on Ladue, the ramp from northbound I-270 to Ladue will close for about two months, but the timing on that has not been determined.  To get more specific information on which lanes will be closed and where traffic will be shifting, please sign up for the e-mail updates below.

What changes can drivers expect as a part of the project?

The two bridges over Ladue Road and Conway Road will be wider and the ramps reconfigured to take advantage of that.  Drivers from I-64 to northbound I-270  will have two lanes to get up to interstate speeds and merge over beyond Ladue, and southbound drivers  heading to I-64 will have more space to exit eastbound and westbound

What construction impacts can drivers expect?

This will be a two-year construction project that will have narrowed lanes and ramps.  In February 2024, crews will start work near the Ladue bridge, with lane closures on Ladue in both directions.  In March 2024,  MoDOT will start work near Conway.  Most of this work will start off the roadway, but drivers can anticipate narrowed lanes on both northbound and southbound I-270 between Conway and Ladue. Crews will also close one northbound lane just after the I-64 exit, with one southbound lane closed around the clock starting in early summer. During peak traffic times, the project's goal is to keep four lanes open across the Ladue Bridge and three through lanes and two ramp lanes open near I-64. During the weekends, nighttime, or off-peak times, there may be additional lane closures. Drivers can see weekly planned road construction on the weekly Road Construction Report. Sometime in early fall, project crews will close the ramp from northbound I-270 to Ladue for a little more than a month.

Drivers heading north or south may want to consider using Lindbergh (U.S. Route 67)  or Route 141 and drivers heading east or west may want to consider  Manchester or Interstate 70. Drivers can also expect times when the ramps between eastbound and westbound I-64 and northbound and southbound I-270 will be narrowed and shifted as crews make improvements.

What are the expected detours?

Although there are no expected full closures of the interstate during the project, drivers may want to consider alternate routes during the work, as congestion levels are expected to be high during construction.

Will sound walls be constructed with this project?

Although the department is widening I-270 here, there are several other criteria that must also be met for MoDOT to consider constructing sound walls.  This project does not meet all the required criteria, so sound walls will not be constructed as a part of this work.

When will the project start?

Work is expected to start in early 2024.  Work should take roughly two years to complete.

What is the timeline?