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Process for Changing Speed Limit 1. Document Existing Conditions Thoroughly understand the existing speed, safety, and traffic characteristics on your system. The outcome of this effort will establish the facts about how your road system is operating and will help you determine if there are real problems that need addressing or only the perception of problems. Establishing how your system is working is a key input to the subsequent effort to evaluate and ultimately select an approach to determine speed limits on your city's streets. Collect speed data on a representative sample of roadways, covering the spectrum of roadways, including low volume residential streets, streets in central business areas, school zones, parks, urban collectors, and urban/suburban arterials. It is likely that these different types of roadways have different operating and safety characteristics, and it is important to be aware of these differences. Document safety characteristics using MnCMAT including total numbers of crashes, the number of serious crashes and fatalities, locations of crashes and contributing factors. MnCMAT can provide both city wide overviews of crash data and specific information about corridors, individual intersections with documentation of numbers of crashes, types of crashes, crash severity and contributing factors. 2. Survey Residents and Elected Officials Understand the concerns of city residents and elected officials regarding safety and vehicle speeds. Separate fact from perception and determine if most residents and elected officials feel a certain way or if there is only a vocal minority. Conversations with public works professionals around the state have found that there is not uniform support for changing urban speed limits. It is important to know where your residents and elected officials stand on this topic as you go through the evaluation of alternatives. 3. Analyze Your Data Most city streets have a 30 mph limit based on the state statute covering urban areas. Collectors and minor arterials generally have higher speed zones that were determined by MnDOT The traditional approach to analyzing speed data involves determining three performance measures: • 50th percentile speed —the speed at which one-half of the drivers are travelling at or less • 85th percentile speed —the speed at which 85 percent of the drivers are travelling at or less • 10 mph Pace —the ten mph range that contains the greatest number of vehicles Conduct an analysis of the speed data collected and determine the 50th and 85th percentile speeds and the 10 mph Pace. Identify the current prevailing speeds across the various classes of streets in your system. Note: Conversations with public works professionals indicate that some cities are finding the 85th percentile speed on their residential streets was around 25 mph, which supported changing the speed limit on those streets as well as an expectation that there would be a high level of compliance. Other cities with different roadway characteristics are finding prevailing speeds that supported retaining the current 30 mph limit. la Page 143 of 185