TIC 2017-10-24 Item 2F - Discussion - Neighborhood Traffic Calming Program: Speed Cushion Implementation Criteria

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City of Tukwila Allan Ekberg, Mayor INFORMATIONAL MEMORANDUM TO: Transportation and Infrastructure Committee FROM: Robin Tischmak, Acting Public Works Director CC: Mayor Ekberg DATE: October 20, 2017 SUBJECT: Neighborhood Traffic Calming Program Project No. 91610410 Speed Cushion Implementation Criteria ggr ISSUE Develop implementation criteria for traffic calming features that include speed cushions and/or radar speed display signs on residential streets if funding is programmed in future budget cycles. BACKGROUND The City's Capital Improvement Program (CIP) has historically included a Neighborhood Traffic Calming Program that is unfunded due to staffing needs. On June 9, 2017, a speed cushion pilot project was implemented on South 160th St to determine the effectiveness of innovative speed cushions in conjunction with radar speed display signs. This pilot project will remain in place for a minimum of one year at S 160th St. Formal criteria are desired for the possible implementation of similar improvements on other residential streets throughout the City in case funding is budgeted to expand this effort into an ongoing program. DISCUSSION Traffic conditions on residential streets greatly affect neighborhood livability. Unnecessary through - traffic and speeding in neighborhoods create safety hazards on residential streets. Traffic calming measures can be implemented to reduce the negative effects of motor vehicle use, alter driver behavior, and improve conditions for pedestrians and bicyclists. In order to ensure that traffic calming concerns are addressed in an equitable manner, a preliminary evaluation must be performed to assess the situation by reviewing important basic criteria to determine if the street qualifies for traffic calming measures. The primary purpose of a preliminary evaluation is to determine whether the speeding or accident history is significant enough to warrant further action. It should be noted that traffic calming improvements will not be recommended in locations where engineering judgment has determined that actions are not warranted. The three criteria listed below are widely accepted engineering measures that provide a consistent, data driven evaluation of conditions on a given street. Example qualifications play include: • Speeding: the speeding criteria is met if 15% of the motorists travel at 10 mph or more above the posted speed limit. • Volume: the traffic volume criteria is met if the volume for the Local Streets are less than 3,000 vehicles per day and Residential Collectors are less than 7,000 vehicles per day. • Traffic Accidents: the number of accidents for Local Streets and Residential Collectors is three or more in one year. 45