I-70 Fifth Street Reconstruction

St. Charles County Transportation Department

Horner & Shifrin designed improvements to I-70 Fifth Street, I-70 Fairground, and I-70/Route 94


Horner & Shifrin led a design team in an effort to increase access along Interstate 70 from Fifth Street to Route 94 and improve traffic flow throughout the project area. Major responsibilities included conceptual design, extensive public involvement, a Design Report, Access Justification Report and final plans, specifications and estimates (PS&E) production for 1.5 miles of roadway in St. Charles County. The project was successfully completed on an aggressive schedule to meet funding milestones.

The project includes the conversion of Fifth Street under I-70 to a diverging diamond interchange (DDI), creating a new interstate interchange at Fairgrounds Road. H&S designed a roundabout for the Fairgrounds/Veterans Memorial Parkway intersection, converting a portion of the two-way outer road to a one-way outer road south of I-70. Plans also included adding an additional lane along the interstate corridor at Route 94, designing two bridges and improving pedestrian access in the area.

Horner & Shifrin continuously coordinated with the client, St. Charles County, as well as other state and local agencies throughout the conceptual design process. This coordination ensured the proposed concept was an agreeable design for all parties involved, while maximizing key factors like access and safety.





St. Charles, Missouri

Year Completed


Innovation. Agility.
Reliability. Horner & Shifrin.