4th St. / Cedar Ave. / Lockett Rd.

Flagstaff, AZ


The City of Flagstaff retained MTJ (as part of the AZTEC team) to evaluate the feasibility of a roundabout application at this highly constrained site. The intersection is located adjacent to elementary/middle school, college, commercial and residential uses.


MTJ Roundabout Engineering developed two geometric designs for evaluation of feasibility. The double-roundabout avoids residential impacts; whereas, the 4-legged roundabout impacts one residence.

Each design achieves operational, accessibility and safety objectives for all modes – vehicular, pedestrian, and cyclists.

Design highlights:

  • Horizontal designs that minimized adverse impacts to surrounding context
  • Designs highlighting safety for all modes
  • Sensitivity analysis to reflect accommodation of future traffic growth


  • Highly constrained context
  • Multimodal safety priority
  • Minimization of adverse impacts, including residential traffic flow
  • 4-leg and double-roundabout alternatives

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