Minutes - Public Works Committee - 01/18/2005

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Case #4: Consider Placement of All Way Stop At Radium Street and 144th Lane City Engineer Jankowski explained that a request has been received from Mr. Gerald Bentler and four additional area residents for the placement of an all way stop condition at the intersection of Radium Street and 144th Lane. Mr. Bentler's letter suggests that the purpose of the signage is to control speeding. Staff has reviewed the intersection and offers the following information as background in considering this request. Accident history A review of the police department records dating back to 1993 show no reported accidents at this intersection. Traffic Traffic counts were taken between the 48 hour period between Monday, November 15, 2004 and Wednesday, November 17, 2004. The results of this traffic volume study were 203 vehicles per day on the west leg; 121 vehicles per day on the east leg; and 112 vehicles per day on the south leg. Sight Distance There is an adequate sight distance in all directions. However, there are several small spruce trees, which are located within the sight distance triangle on the southwest corner on the intersection. These trees are a minimal obstruction at this time but will become a significant problem as they mature. The request was made for the posting of an all way stop at this intersection. The Minnesota Manual On Uniform Traffic Control Devices (MMUTCD), which provides guidance on the placement of traffic control devices including stop signs, requires minimum traffic volumes far exceeding the existing traffic volumes at the intersection under study. The traffic volume for an all way stop requires an average of 300 vehicles per hour for eight hours per day on the major street, and an average traffic volume of 200 vehicles per hour on the minor street for eight hour per day. A tenfold increase in traffic would not generate sufficient volume to meet the manual guidance criteria at this location. It might be noted that all way stop signs have been placed at several other intersections within this same neighborhood. These locations include the intersections of Potassium 8,: 145th Lane; Tungsten Way 8,: 144th Lane, Tungsten 8,: 142nd Lane, Potassium 8:143rd Lane, and Neon 8:142nd Avenue. These all way stop locations were posted as a result of Council direction to study and make recommendations on an overall plan to calm traffic through this neighborhood. Although these all stop locations may also fall short of the MMUTCD traffic volume guidance, they have been placed on the higher volume neighborhood streets and have been somewhat uniformly spaced throughout the neighborhood. It should also be noted that the request was generated by the desire to reduce speeding. The MMUTCD specifically advises against the placement of stop signs for the purpose on controlling speeding. Experience has shown that on low volume roadways there is a high percentage of noncompliance with stop signs in situations where local drivers know there is a small probability of encountering another vehicle within the intersection. In addition, studies have shown that where stop signs are used for the purpose of speed control speeds decrease within a couple of hundred feet of the intersection, but the speeds at mid-block tend to increase. Presumably this effect is caused by motorists wanting to make up the time they lost stopping or slowing down for the stop. In Public Works Committee/January 18, 2005 Page 14 of 27