Long Road/Kehrs Mill Road at Highway CC (Wild Horse Creek Road) was an offset intersection with State Hwy CC. As growth continued westward in St. Louis County, the two T intersections experienced severe traffic congestion. Two traffic signals at these intersections created inefficient traffic movement for vehicles traveling on Kehrs Mill Road and Long Road, resulting in vehicles stopping twice. Burns & McDonnell was retained by St. Louis County Department of Highways and Traffic to improve the intersection configuration and increase capacity on Long and Kehrs Mill Roads.
Burns & McDonnell developed two alternatives for the project. The first would realign Long Road and Highway CC to make this the through traffic movement. Kehrs Mill Road would tee into the realigned Long Road, and Highway CC would tie into Kehrs Mill Road. This alternative would support the highest traffic movement from eastbound Highway CC to northbound Long Road. The second alternative would realign Long Road to create a four-way intersection with Kehrs Mill Road and Highway CC. Both alternatives required purchasing right-of-way and easements.
Safety of pedestrians and bicyclists was a primary concern in this fully developed area, particularly for the widened roadway. The conceptual design considered sidewalks and multi-use paths on one or both sides of the road, and recommendations were made for a two-way multiuse path on one side of the road, responding to physical constraints in the area. Accommodations were made at the railroad tracks for the bike paths. Pedestrian mazes were used rather than standard crossing arms, which could trap pedestrians near railroad tracks.
Several design criteria had to be met to maintain the current infrastructure and coordinate with proposed expansion in the area. The existing infrastructure included a railroad crossing 1,000 feet from the proposed intersection of Long Road and Highway CC. Between the railroad and the relocated intersection, Bonhomme Creek crosses the relocated Long Road. In addition, the U.S. Army Corp of Engineers (USACE) was constructing a levee along Bonhomme Creek. The relocated Long Road bridge ties into the USACE levee.
The project also faced challenges with existing underground utilities, including a 42-inch water main, a fiber optic line and natural gas lines.
- Topographic field survey
- Property surveys
- Geotechnical surveys and report
- Right-of-way documents
- Environmental coordination and documentation
- Preliminary bridge design and hydraulic report
- Roadway and bridge plans
- Maintenance of traffic
- Railroad coordination
- ADA compliance
- Cost estimate