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I-64 widening - I-270 to Route 340

Placing drainage

Crews place drainage in preparation of the widening work. For more photos, click here.

What is going on?

Crews continue to work on the eastbound lanes between Route 141 and I-270.  Drivers can expect narrowed eastbound lanes with barrier wall to the outside.  Drivers can also expect a long-term left lane closure on the south outer road between Route 141 and I-270.  In addition the ramp from the south outer road to EB I-64 between Maryville Center Drive and Mason is permanently closed -- crews have opened the new exit ramp from the interstate to the south outer road.  The ramps at Route 141 and Mason to the interstate remain open. Crews are also working to overlay the westbound lanes between Ballas and Route 340.  They should be completed with the overlay in late summer and all westbound lanes should be opened to traffic.

What is the problem?

Traffic on I-64 between Route 141 and I-270

During the morning and evening commutes, much of I-64 is congested between I-270 and Route 340(Olive Boulevard/Clarkson Road). At this point, nearly 150,000 vehicles travel this section of roadway, and in 20 years, that number could increase to more than 175,000 vehicles. The levels of eastbound congestion in the morning and westbound congestion in the evening will continue to increase in the area if nothing is done.

What does the project entail?

The project will add one lane in each direction on sections of I-64, similar to what was done on I-270 between I-44 and Manchester Road. Due to funding, the widening will not be equal on both eastbound and westbound I-64. The department will add one lane westbound between I-270 and Route 340; the added eastbound lane will run from Route 141 to I-270.

The department will widen the road slightly and then restripe all lanes to 11 feet to add the extra lane. The department will retain full, 10-foot wide shoulders throughout most of the project to ensure the safety of drivers who may have to pull off the roadway. The only exceptions to this will be the shoulders near the bridges over Route 141 and Creve Coeur Creek, where we will reduce the shoulders to be able to get lanes on the existing bridges.

 On eastbound I-64, both the off-ramp to Maryville Center and the on-ramp before Mason will be moved further to the east. The department will also make some improvements to the interchange at Route 141, adding additional turn lanes and improvements between I-64 and St. Luke’s Hospital Drive.

Project information

Will I-64 in that area be made any flatter?

No.  The department will not be flattening out any of the hills on this section of I-64.

How will this impact traffic through construction?

The department will maintain the current number of through lanes in each direction during rush periods throughout construction. Similar to the I-270 widening project, lanes will be narrowed and shifted and all work will take place behind barrier walls. There may be impacts to eastbound traffic when the ramps to Maryville Center and the on-ramp before Mason are shifted further east.

Why isn’t this project adding lanes through the Chesterfield Valley?  Traffic backs up there on I-64 as well.

Much of the backups on westbound I-64 are due to the narrow lanes on the 1930s-era Daniel Boone Bridge.  After crews complete renovating the current eastbound bridge and move westbound traffic to it in late 2015, the traffic congestion in the Chesterfield Valley should significantly reduce.  For more details on the Daniel Boone Bridge project, please click here.

On eastbound I-64, there are backups as drivers approach Route 340 (Clarkson/Olive).  There is a need to add more lanes in this area in the future, but no funds have been identified for a project in this area at this time.

Will construction impact property owners around the project?

The department will make all the improvements necessary on both eastbound and westbound lanes within the department’s current right of way. No significant changes are anticipated to the north or south outer roads on I-64.

How successful has been the similar project on I-270?

I-270 between I-44 and Manchester Road has become a more reliable section of roadway since MoDOT added the lane northbound and southbound.  Traffic speeds during the most congested times have increased, despite an increase in traffic levels, while the amount of time the roadway is currently congested has dropped.

What is the timeline?*

Project public meetings

June 2014

Contract awarded

August 2014

Construction starts – westbound

Spring 2015

Construction starts – eastbound

Early 2016

Construction ends

Late 2016

 *Note: all timeline milestones are subject to change

How will this impact other major roadways (Route 141, Route 340)?

The impact of the widening project will have a minimal impact on other major roadways in the area. There may be non-rush hour lane closures during the project. The construction on Route 141 as part of this project will have off-peak lane closures.

Are soundwalls a part of the project?

Federal Highway Administration (FHWA) requires MoDOT to conduct a sound study any time it plans to add lanes to an existing highway or change the location of a road. FHWA sets guidelines for sound mitigation, and all states are required to set up their policies for sound walls within those guidelines. There are several criteria which need to be met to determine if a community is eligible for sound walls. MoDOT is currently completing the study for this project and will share the information with the public (and homeowners near the project) at a public meeting currently planned for June 2014.  For details on the requirements for soundwall eligibility, please see our soundwall information here.

Noise walls information

For more information:


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