Missouri Route 340 Pavement Resurfacing in St. Louis County

The following general themes were shared by the public during an April 14, 2026 public meeting at the Clarkson Valley City Hall council chamber, and on-line through April 28, 2026. You can view the full summary of the public meeting here: Route 340 April 14 public meeting summary link

Concerns about congestion caused by signal timing and high volumes. 

Several signals along the corridor are being replaced in the upcoming project while others are getting new detection systems. Updating detection should allow for the existing optimized timing plan to be more reliable. Intersections where timing issues continue to be reported can be reviewed by the Area Traffic Engineers. Most corridors receive a new optimized timing plan every five years, and this portion of Clarkson Road is due to be reviewed and updated within the next two or three years. The current median islands provide traffic calming and access management. No new median islands are planned to be installed but median islands that currently exist will remain in place with no further adjustments made. Congestion currently in the section of the project north of Baxter should be improved by the construction of additional northbound and southbound lanes, completed by the Downtown Chesterfield Development. 

Extending or creating turn lanes at intersections and neighborhoods. 

The design and traffic teams are currently reviewing to see which locations may have volumes that are high enough to make right turn effective, and where the existing shoulder can support additional turning traffic. Once evaluated, these areas can be included in the upcoming project, since they can be completed by updating the pavement markings after the resurfacing project is complete. Those areas where the existing shoulder cannot support additional traffic because it needs more robust pavement will be considered in a future project.

Additional pedestrian and bike facilities along route. 

The department is aware of the community’s desire to improve safe access for all users of the corridor.  These improvements will need to be considered in a future project. 

Traffic law (speed, aggressive or distracted driving) enforcement. 

MoDOT is not an enforcement agency and law enforcement organizations do not work for the department. Although the department can, and will, share these comments with our law enforcement partners, it is often more effective for residents to share their concerns directly with local municipality leaders and local police departments.

Speed limit for Clarkson should be consistent. 

The current posted speed limit for Clarkson Road will be reevaluated during the next signal timing optimization study in two to three years. 

Concerns about how the project will be constructed.

This information was shared during the public meeting. Most of the signal work will take place during the day, with lane closures on the corridor taking place outside of peak traffic times.  Due to the greater impact of the work, and general availability of asphalt plants, the resurfacing work will take place during overnight hours.  Overall, noise impacts during the night work on specific locations will be low – on average less than once/week over the course of resurfacing the entire corridor.