Agenda - Public Works Committee - 08/17/1999

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Sight Distance - The approach sight distances are as follows: NB - significant limitation to east from landscaping berm SB - good visibility EB - slight limitation to the south from rising grade WB - slight limitation to the south from landscape berm Traffic Volume - Traffic counts were taken on 137th Avenue and Garnet Street in July 1999. The north leg of the intersection has 448 ADT, the west leg 218 ADT, the east leg t78 ADT, and the south leg is estimated to generate 80 ADT. Observations - According to the petitioner's request, the placement of stop signs would be an attempt to slow down the traffic. The length of 137th Avenue is 2100 feet long through the Rivenwick subdivision. A stop sign would provide reduced speed through a 300-foot stretch of this distance, 150 feet either side of the intersection. The sight distance from the southern leg of this intersection has some limitations. This limitation may have contributed to the single accident recorded at that intersection. Posting a stop sign as requested on 137th Avenue would give the right-of-way to northbound and southbound traffic on Garnet, which is not the predominant movement. Granting the right-of-way to the non-predominant movement is unwise, particularly on low-speed, tow volume intersections such as this, since there is a significant percentage of traffic that will disregard the stop because of the low probability of having a conflict. The danger of an accident would be further compounded by allowing northbound Garnet Street, with a diminished sight distance, the righ~:-of-way. Recommendation - Staff's first inclination would be to recommend stop signs on Garnet, facilitating the predominant movements through I37th Avenue and requiring Garnet traffic, which has diminished sight lines along I37th, to yield the fight-of-way. When stopped at the corer of the intersection on northbound Garnet, the sight lines along 137th Avenue are completely clear. However, this may lead to increased speeds along 137tn Avenue, which has already been described as problematic. Hence, staff's recommendation is to leave the intersection uncontrolled. 137th Lane and Garnet Street Accident History - There have been no accidents for this location reported to the police over the 6½-year period beginning January 1, 1993. Sight Lines - The approach sight distances are as follows: NB - slight limitation to the west from rising grade and small spruce trees SB - good visibility EB - good visibility WB - slight limitation to the north from rising grade Traffic Volume - Traffic counts were taken on Garnet Street in July 1999. The north leg of the intersection has 62t ADT while the south leg has 418 ADT. The west and east legs are estimated to have 280 and 80 ADT respectively.