W. Quincy Ave. and S. Simms St.

Jefferson County, CO


MTJ  Roundabout Engineering was retained by Jefferson County to provide design mitigations to improve driver comprehension and reduce the number of crashes at the Quincy/Simms roundabout near Denver.


The MTJ design modification recommendations were predicated on:

  • Improving driver comprehension to mitigate driver errors
  • Matching capacity to demand to reduce conflict points
  • Simplifying drivers’ decision-making
  • Adhering to roundabout geometric safety principles
  • Best practices for roundabout signing and marking



  • Improved driver guidance
  • Reduced conflict points
  • Improved operations
  • Improved safety design
  • Simplified driver decision-making


MTJ also conducted a review of the nearby Simms/Nassau roundabout, and developed concept-level recommendations to ensure:  lane continuity between the roundabouts and the US-285 interchange ramp, simplified driver decision-making, and improved safety performance.