Interstate 55 Widening

Interstate 55 Widening

Location: St. Louis

Client: Missouri Department of Transportation

Completion Date: 2003

Burns & McDonnell prepared construction plans for the reconstruction of Interstate 55 from south of Richardson Road to north of Route M. This 4.2 mile stretch of urban interstate was widened from four to eight lanes. It is expected to carry 114,500 cars per day by 2015.

Both the existing interchange with Imperial Main Street and its bridge over I-55 were functionally deficient and had to be reconstructed to modern interstate standards. This necessitated the relocation of 2,150 feet of outer roadway and the relocation of utilities including a 22-inch natural gas line. As part of the improvements to the interchange the existing span wire traffic signals at three intersections were replaced with fiber optically interconnected traffic signals and lighting.


  • 2003 Consulting Engineers Council of Missouri Engineering Excellence Award - Honorable Mention
  • 2003 Quality Concrete Award through the Concrete Council of St. Louis
  • Conceptual design
  • Preliminary plans
  • Right-of-way plans
  • Construction plans
  • Specifications
  • Cost estimates

Detailed construction phasing and traffic control plans were developed for the project. A detour was signed along Route 61/67, and traffic signal modifications were included at several signalized intersections along the detour to accommodate increased traffic flow.

Due to the significant cost of a project this size, it was separated into three construction packages totaling $32 million. Construction began on the first project in 2001 and was completed in 2003.


  • Traffic studies
  • Geometric design
  • Traffic signals
  • Fiber optic interconnection
  • Lighting
  • Technical specifications
  • Pedestrian signals
  • Commuter parking
  • Environmental mitigation