10-02-2017 Council Packet - Laserfiche WebLink

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While the MnMUTCD recommends setting the posted speed limits near the 85th percentile speed, and traffic engineers say that agencies are using the 85th percentile speed to set speed limits, the speed limit is often set much lower. At these locations, the 85th percentile operating speeds exceed the posted speed limits; and, in many cases, the 50th percentile operating speed is either near or exceeds that posted speed limit as well. Many agencies deviate from their agency's written guidelines and instead post lower speed limits. According to an ITE Engineering Council Technical Committee survey, these reduced speed limits are often the result of political pressures. However, it is important to note that setting speed limits lower than 85th percentile speed does not encourage compliance with the posted speed limit. Speed Limit Implementation: The City Lino Lakes has established this policy to define the process for setting a speed limit and to what extent they can be modified. To make a request for a speed limit change, one must send a formal written document to the city. The local road authority can either determine the speed limit acceptable, not acceptable, perform an engineering investigation or request the Commissioner of Transportation do a speed study. Streets that drive relatively similar should be set to the same speed limit for consistency, whether they are 25, 30, 35, or 40 mph. Speed limit evaluations should only take place when specific concerns are raised, and not on a regular basis. When final decisions are made they are not to be requested upon again unless a situation occurs (i.e., a large development is being constructed, or multiple accident occurs). If further monitoring needs to occur on a street, driver feedback signs or physical changes may be considered. Speed Concern Evaluation: If a speed concern still exists after the determination of the appropriate posted speed limit based on the criteria previously discussed, additional speed mitigation/traffic calming could be considered based on the following guidelines. Eligibility: In order for a roadway to be eligible for speed mitigation/traffic calming, it needs to meet the following criteria. • Classified as a local or collector street • Length greater than 1,000 feet • Traffic volumes greater than 1,000 vehicles per day • Posted speed of 30 mph or less • Cannot be a cul-de-sac Evaluation Process: If the roadway is eligible for speed mitigation/traffic calming, a preliminary study will be conducted using collected data. In analyzing the speed data, the 85th percentile speed of the collected data will be calculated. The 85th percentile speed is defined as the speed at or below which 85 percent of the traffic is moving.