Frequently Asked Questions

The I-70 Cave Springs to Fairgrounds project is a Design-Build project that will make improvements to increase safety, make the interchanges smoother to move through and support local access. This is an area that is very congested and has a high number of crashes. This project aims to improve traffic flow in the area.

The project is in eastern St. Charles County of the St. Louis Region, on I-70. The limits of the project are from Fairgrounds Road – just west of the Blanchette Bridge – four miles west to Cave Springs Road.

Infrastructure upgrades are needed because the population of St. Charles County is nearly three times what it was in 1980 when these interchanges were built.

  • TRAFFIC: The Cave Springs and Zumbehl interchanges often experience traffic jams making it tough for traffic to flow through the area. During the morning rush, vehicles crossing the interchange average a speed of 18 mph on Zumbehl Road and 7 mph on Cave Springs.
  • SAFETY: These delays cause traffic to back up onto I-70, creating a serious risk to safety. The interchanges have a higher than average crash rate. Between 2013 and 2017 the average crash rate in the area was more than 40% above the statewide average rate.
  • CONNECTIVITY: The outer roads in the area are disconnected which sends local traffic onto the interstate or other local streets.

MoDOT, working in coordination with St. Charles County, the City of St. Charles and St. Peters developed the project goals. These goals set the vision for the project.

  1. Maximize improvements within the program budget of $62 million.
  2. Improve safety and efficiency of the transportation network while supporting connectivity for the local community.
  3. Provide a durable and maintainable transportation infrastructure allowing for future expansion.
  4. Minimize impacts to the traveling public during construction while safely delivering the project by November 1, 2023.
  5. Deliver the project using a diverse workforce.

The total project budget is $62 million. That includes $52 million of State and Federal funds and $10 million from St. Charles County.

There are many different solutions that are available to solve the complex issues that exist along this stretch of I-70. Design-Build teams will compete to achieve solutions that meet the project goals and balance the needs of the community.

Design-Build projects allow MoDOT to award the design and construction of a project to the team that can provide the best overall quality of improvements for the fixed budget. roject goals are used to judge the quality of the projects presented. To learn more about how Design-Build works, visit

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