Lake St. Louis Blvd. / Veterans Memorial Pkwy. / Interstate 70

Lake St. Louis, MO

• ACEC Missouri’s Engineering Excellence Honor Award
• Missouri Chapter APWA: Public Works Project of the Year Nomination


The City of Lake St. Louis conducted a concept study to improve the function of the two closely spaced intersections at Veterans Memorial Parkway and the eastbound ramps of I-70 on Lake St. Louis Blvd. This analysis included evaluating roundabout options for addressing the closely spaced intersections that were experiencing congestion and safety issues.


MTJ’s work, as part of the project team led by Oates Associates, included completing an operational analysis and developing two roundabout concepts to address the close spacing of the two existing intersections:

Alternative 1: Two closely spaced, 4-leg roundabouts that allowed for the segregation of traffic streams and reduced circulating flow past downstream entries.

Alternative 2: One 6-leg roundabout with additional entry lanes.

The 6-leg roundabout alternative was selected due to:

  • Enabling existing signal to perform better due to improved lane continuity
  • Creating fewer weaving and lane balance issues
  • Acceptable ROW and environmental impacts

Key to these recommendations was MTJ’s unparalleled roundabout analysis and design expertise that ensured accurate evaluation of feasible alternatives. This provided high levels of confidence in the resulting decisions. MTJ is again teaming with Oates Associates on the final design for this challenging site. Construction is planned for 2020.


  • Evaluation results recommended 6-leg roundabout alternative
  • Successfully addressed closely spaced intersection needs
  • Improved safety and reduced congestion

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