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, which leads to lengthy travel times, and has a high number of crashes. This project aims to improve traffic flow in the area.

The project is on I-70 in eastern St. Charles County. 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 originally built.

• CONNECTIVITY: The outer roads in the area are disconnected which sends local traffic onto the interstate or other local streets. In addition, connectivity is impacted by heavy congestion—increasing the time it takes to get through the area.
• SAFETY: Traffic delays cause vehicles 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.
• 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.

Addressing these three issues will help the traveling public get where they need to go quickly, safely, and easily.

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

1. Improve connectivity for the local community while maximizing safety and efficiency of the transportation network within the program budget of $62 million.
2. Provide a durable and maintainable transportation infrastructure allowing for future expansion.
3. Minimize impacts to the traveling public during construction while safely delivering the project by June 28, 2024.
4. 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.

The outer roads, interchanges and interstate are all tied together. Improving how the outer roads connect with the interchanges would improve not only how the interchanges work but safety on the outer roads and the interstate. There is tight spacing throughout this corridor. It will be important for project teams to use the available space wisely.

No they are not. MoDOT will consider many different solutions through the Design-Build process. Those solutions could include converting the outer roads to one-way in order to make the interchanges safer and easier to get through.

The outer roads and the interstate are all a part of the interchange system – along with the cross streets and interstate ramps. Making changes to one part of the interchange will have impacts to the rest of them.

Signal synchronization has been happening for years, but the effectiveness is limited by the amount of traffic using these outdated interchanges. Another thing to keep in mind is that changing the signal timing at the interchanges can have a ripple effect to the next adjacent intersections.

There are several factors that will determine whether a soundwall will be built. To be eligible to be constructed, any particular soundwall must meet the following criteria:

• Predicted noise levels for the highway must exceed 66 decibels in the study area.
• The sound wall must have a reduction of at least 7 decibels in the outdoor living space of the first-row properties.
• The sound wall cannot be taller than 20 feet for safety.
• The sound wall must be built on state property and meet safety and maintenance requirements.
• The sound wall must require less than 1,300 square feet of wall (on average) per benefitted recipient.
• A majority of benefitted owners and residents must vote in favor of the sound wall.

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. Project goals are used to judge the quality of the projects presented. Learn more about Design-Build.

MoDOT has had great success with Design-Build projects in the past. Design-build promotes innovation by soliciting competition from the industry for not only construction, but design, since the solution is not set in stone at the beginning of the project. Because of this competition between industry partners, the traveling public has received more improvements for their tax dollars and the projects tend to be completed more quickly. This not only saves time and money but brings new technologies to the State of Missouri. Since 2007, MoDOT has procured $2.5 billion in Design-Build and saved $314 million in funding and over nearly 9 years. Successful Design-Build projects in St. Charles County include Route 364/Page Phase 3, the new Daniel Boone Missouri River Bridge and the St. Louis Safety Design-Build Project.

Large transportation investments, like this $62 million project, are prioritized by our regional planning process that is managed by East West Gateway Council of Governments (EWGCOG) – the federally established Municipal Planning Organization for St. Louis Region. EWGCOG is governed by a 29 member Board of Directors that is comprised of local government representatives and citizens. The final decisions of such large regional priorities are made by formal vote of the EWGCOG Board of Directors by approval of STL Regional Long-Range Transportation Plan and Transportation Improvement Program.

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