Through regular Vision Zero analysis and reporting by Boulder, speeding has been identified as a major factor in severe injury and fatal crashes, with one in three severe crashes related to speeding in the last three years of published data. Consequently, a recommendation from the Vision Zero Action Plan was to establish a citywide methodology for identifying context-sensitive speed limits.

Y2K Engineering led this initiative, which included extensive research on national best practices and tools, interviews with peer agencies that have citywide, systemic approaches to setting speed limits, and an iterative, collaborative development process with City staff.

Once developed, Y2K applied the methodology to Boulder streets. This effort included the most extensive data collection ever conducted by the City, with speed and volume data gathered from over 200 locations for inclusion in the GIS-based analysis. Existing speed data, along with fifteen other factors such as speed-related crash history, pedestrian and bicycle activity, surrounding land use, and whether a corridor is part of the City's high-risk network, were analyzed. The process determined the appropriate speed limit for each roadway, choosing from the rounded-down 50th percentile, 50th percentile, rounded-down 85th percentile, or 85th percentile speed.

This innovative, first-of-its-kind approach to setting speed limits citywide has enhanced the consistency of Boulder’s speed limit policies by grounding them in data. This initiative directly addresses an objective from their Vision Zero plan, and will lead to a safer Boulder.