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CITY OF Pr~EASANTON <br />VEHICr, F. SIGHT DISTANCE REQUIREMENTS <br /> <br />ATTACHMENT 1 <br /> <br />The following criteria should be considered when designing, plan checking, or mainlining <br />new rOadway landscaping in order to prevent motorism' vision ~rom being obscured by treea <br />and shrubbery. These criteria are not entirely "empirical" but do represent a good "rule of <br />thumb" for creating safe, nonsignaliT_~ intersections. For the most pail, the.se criteria are in <br />conformance with the recommendations of AASHTO (American Association of State <br />Highway Transportation Officials), while some of th6 criteria are in fact more conservative. <br /> <br />The height of the driver, s eye should be assumed to be three and one-half (3.5) feet <br />above the surface of the roadway.. If legally stopped at an'in~".rsection, the driver's <br />precise' localion is a point thirteen (13) feet behind the stop-bar and four (4) feet to <br />the fight of the roadway cen~fiine. (Refer to the diagram below.) <br /> <br />It should be assumed that the overall height of a vehicle wavelling on' the roadway is <br />not more than four (4) feet above the surface of the roadway. <br /> <br />As the posted speed of the traffic increases, the required safe sight distance must also <br />increase. A posted speed limit of 25 MPH requires an unobstructed sight.distance of <br />250 feet; a speed limit of 35 mph, 350 feet, and so on. "For each 10 mph of posted <br />vehicle speed, an unobstructed view of 100 feet in the direction of oncoming or <br />competing U'affic is required." <br /> <br />stop bar <br /> ! <br /> <br />Example: <br /> <br />A vehicle legally stopped at a 'T' intersection is planning to make <br />a left turn onto roadway A. The minimum sight distance required <br />to see and react to competing traffic is 350 feet. <br /> <br /> <br />