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. The current traffic jams also make navigating this area complex.
• SAFETY: The interchanges have a higher-than-average crash rate. There were over 3,000 crashes in this corridor between 2013 and 2017. That averages out to two crashes a day.
• 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 Cave Springs average only 7 mph between West Clay and Veterans Memorial Parkway. Delays due to congestion regularly cause traffic to back up onto I-70.

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.

This project maintains the existing two-way outer roads system. The way people travel through and within the corridor today will not drastically change, in fact, connectivity within the corridor will improve. Our Project restores the Veteran’s Memorial Parkway connection under Cave Springs and build new north outer roads between Fairgrounds and Zumbehl.

The biggest issue at Cave Springs is the number and proximity of signals in the intersection. The five signals that exist today are too closely spaced which causes congestion and crashes.

Our Project will eliminate two signals and improve signal spacing by replacing the existing interchange with a Single Point Urban Interchange (SPUI) and build a new bridge over Veterans Memorial Parkway.

The new Cave Springs interchange will look and function similar to the Route 94 interchange. The intersection of Cave Springs and Veterans Memorial Parkway will also look and function similar to the intersection of Route 94 and Veterans Memorial Parkway.

These improvements will help make the interchange less congested during morning and afternoon rush hours and greatly reduce the anticipated number of crashes in the corridor.

A SPUI is a shortened name for a single-point urban interchange. A SPUI moves more traffic through a smaller amount of space compared to the cloverleaf design, which takes up a much greater amount of land. The SPUI design makes it easier to build new interchanges within existing state property.

In the single-point urban interchange, the streams of left-turning traffic do not cross. Opposing left turns can be made at the same time; with only one set of traffic signals, more vehicles can make the turn and clear the interchange in one traffic signal cycle. SPUI also allow for long, gradual turns. Larger vehicles like trucks, buses and recreational vehicles have more room to navigate. Traffic moves more smoothly, and everyone can breathe a little easier.

The single-point urban interchange is very safe for pedestrians and bicycles. The pedestrian path is well marked through the use of curbs and medians, different colored materials, or through the use of more substantial structures.

Yes. Our Project is focused on providing solutions at the areas where most accidents occur, currently at the Cave Springs and Zumbehl interchanges. By reconfiguring the interchanges and providing for increased signal spacing, we greatly reduce the number of anticipated crashes. Throughout the corridor, we are also providing targeted solutions where crashes are frequent. For example, at Route 94, where we are providing modified right turns to reduce crashes at Boone’s Lick and VMP intersections.

No. We are utilizing the existing two-way outer roads in-place. While your physical travel distance will remain largely the same, improvements we are making at the Cave Springs, Zumbehl, and Route 94 interchanges will reduce congestion throughout the corridor, so you may get there in less time. Additionally, we are proposing new outer road connections between Fairgrounds and Zumbehl, so depending on where you’re traveling, the distance may actually be shorter.

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.

For Industry Information on this Design-Build project click here.

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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Click here to see information presented at the open house meeting on June 28, 2022.