Title
Consider and take action on an Ordinance to set a 30 miles per hour (mph) speed limit along Isla Vista Drive between State Highway 96 and Mar Bella Parkway, a distance of approximately 1.56 miles (Executive Director of Development Services)
Staff requests approval on first and final reading.
Background:
Approval of this item will set a 30 mph speed limit along along Isla Vista Drive between State Highway 96 (SH 96) and Mar Bella Parkway. Exhibit A shows an aerial map of the study corridor. Isla Vista Drive is a "Collector" roadway in the Mar Bella subdivision and as per Section 110-166 of the City's Code of Ordinances, a 35 mph speed limit should be used unless Council action designates otherwise. The existing speed limit on Isla Vista Drive is 25 mph.
A speed zone study was performed to evaluate the existing speed limit on Isla Vista Drive between SH 96 and Mar Bella Parkway. Data collection for the speed zone study included site investigation, traffic volume and spot speed data (provided in Exhibit B) and crash data (provided in Exhibit C).
The 11th edition of the American Association of State Highway and Transportation Official’s (AASHTO) A Policy on Geometric Design of Highways and Streets guidelines recommend using the 85th percentile speed as a starting point for setting speed limits. The study found that the 85th percentile speed was 36 mph. This indicated that the posted speed limit was lower than the typical driving speed. While increasing the speed limit to align more closely with the 85th percentile speed was considered, the roadway context presented safety concerns due to the nature of historic crashes along the corridor, sight distance issues, and the general roadway geometry (horizontal curves).
The study recommended increasing the speed limit on Isla Vista Drive between SH 96 and Mar Bella Parkway from 25 mph to 30 mph to balance the need to accommodate observed traffic speeds with the existing safety concerns.
Staff requests a fir...
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