10-09-2017 Council Packet - Laserfiche WebLink

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NOTE: Federal and State speed limit guidelines define the 85th percentile speed as a “reasonable speed” or the speed in which 85% of motorists travel at or below. Experience has shown that the 85th Percentile Speed most closely provides for a safe and reasonable speed limit. Therefore, it can be expected that on a typical roadway, approximately 15 percent of the vehicles may traveling at speeds greater than the posted speed limit. If a preliminary speeding issue is identified, City staff will first determine if low cost measures are feasible. If low cost measures are not feasible, the process will skip to the next step. Some low cost measures include: • Education and enforcement • Lane narrowing (striping) • Pavement messages (30 MPH, SLOW) • Additional signage • Improve sight lines through tree / branch removal or grading (safety improvement) If low cost measures are deemed feasible, the appropriate measures will be implemented by the City once funding is secured. Possible funding sources include: • Inclusion in the City’s Capital Improvement Plan (CIP) • Special request from the City Council The City will then monitor the traffic conditions over a 3-month period. After the 3-month period, the City will then collect new speed data. If the analysis indicates a speeding problem still exists, education and enforcement will continue while a Level 2 analysis is conducted. Level 2 Analysis: A Level 2 analysis consists of a formal speed study to determine the actual, free flow speed of vehicles on a roadway. A formal speed study differs from tube counts or speed trailer collected data in that recorded speeds reflect how vehicles typically travel along unimpeded sections of the road under free flow conditions. Therefore, not all vehicles have their speeds recorded as with tube counters or speed trailers. Only the lead vehicle in a platoon of vehicles has its speed recorded. This is because the trailing vehicles’ speeds are being metered by the lead vehicle and don’t necessarily reflect free flow conditions. Collecting speeds in this manner is typically done with a hand held radar unit, giving the operator the discretion of whether or not to include the vehicle’s speed based on actual observed free flow conditions. Only those vehicles traveling at free flow speeds are recorded and evaluated. This method of collecting speed data most closely matches that used to set speed limits. This type of analysis was reserved for this stage in the process due to the increased cost of collecting the data. From the collected data, the 85th Percentile Speed and the Pace will again be determined and evaluated. For a formal speed study, the City’s established threshold for a speeding problem is an 85th percentile speed equal to or greater than 33 miles per hour on a street posted at 30 miles per hour. If the street is deemed to have a speeding problem, the City will begin development of traffic calming alternatives to address the specific situation.