Initial Study MND - Sonoma County Agricultural Preservation and ...

Taylor MountainINITIAL STUDY/MITIGATED NEGATIVE DECLARATIONc. Would the project result in a change in air traffic patterns, including either an increase intraffic levels or a change in location that results in substantial safety risks?NO IMPACT. No operating airports or heliports are within two miles of the project site. Theproposed project would not include any features that would have the capacity to impact airtraffic.d. Would the project substantially increase hazards because of a design feature orincompatible uses?LESS THAN SIGNIFICANT. There are no unusual conditions that represent obvious safety hazards.While the proposed project would increase the number of vehicle trips on roads in the projectarea, vehicles would not be exposed to increased hazards as result of the project. Designfeatures of the proposed staging areas would not cause roadway hazards, and no incompatibleuses would occur. To reach this conclusion, a comprehensive review of collision hazards andsight distance conditions was conducted.Sight DistanceSight distance along Petaluma Hill Road at the Preserve’s proposed driveways was evaluatedbased on sight distance criteria contained in A Policy on Geometric Design on Highways andStreets published by American Association of State Highway and Transportation Officials(AASHTO). These guidelines include recommended sight distances at intersections, includingstopping sight distances for drivers traveling along the major approaches and for drivers ofstopped vehicles at the minor street approaches and driveways. These recommendations arebased upon approach travel speeds, and take into account which direction a vehicle would turnonto the major approach, with greater sight distance needed for the more time-consuming taskof turning left as compared to turning right.Sight distance at the northern and southern driveway locations were field measured. Based ona design speed of 55 mph, which is the posted speed limit on Petaluma Hill Drive along thePreserve’s frontage, the northern driveway marginally meets sight distance requirements for allmovements. However, this driveway will be restricted to allow only right-turn movements. Atthe southern driveway, where left-turns would be allowed, sight lines would be adequate for allmovements. Accordingly, since the northern driveway is proposed to be limited to right turnaccess, no further changes to access at this location are recommended.Since the Farmers Lane Extension did not exist at the time of this analysis, it was not possible tofield-measure the required sight lines at the proposed driveway. Therefore, Master PlanStandard 200 states that when the proposed driveway connecting to the Farmers LaneExtension is designed, it will need to be designed in a manner that ensures that adequate sightlines are provided.CollisionsThe collision history for the study area was reviewed to determine any trends or patterns thatmay indicate a transportation safety issue. Since collision analysis is dependent on historicdata, only the following intersections that currently exist were included in the analysis:Final B-116 September 2012