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BACKGROUND <br /> Staff reviews and updates speed limits on a yearly basis to ensure that the posted limits <br /> provide the most orderly movement of traffic in a safe and efficient manner and that all <br /> posted limits conform to the requirements outlined in the California Vehicle Code (CVC). <br /> The CVC requires that engineering staff complete an Engineering and Traffic Survey on <br /> all roads that are recognized by the Federal Highway Administration as a non-local <br /> road'. These surveys must be updated every seven years or when roadway conditions <br /> change. The CVC identifies the California Manual of Uniform Traffic Control Devices <br /> (MUTCD) as the source to specify the required content of an Engineering and Traffic <br /> Survey and the method to assigning speed limits. <br /> The MUTCD states that Engineering and Traffic Surveys must include a record of the <br /> free-flow vehicular speed on the road segment, accident data and any unusual <br /> conditions. The MUTCD also indicates that speed limits should normally be established <br /> at the 5 mph increment nearest the 85% speed2 and that a further reduction of 5 mph is <br /> acceptable where unusual conditions exist or excessive speed-related accidents have <br /> occurred. <br /> The basis for the 85th percentile speed (also known as critical speed) comes from the <br /> California Vehicle Code's Basic Speed Law, which states that no person shall drive at a <br /> speed greater than is reasonable or prudent. It is assumed that the majority of drivers <br /> comply with this law and, for this reason, the 85th percentile speed is used as a <br /> benchmark for what the majority of drivers feel is a safe driving speed. This benchmark <br /> serves as a consensus of those who drive on the roadway as to what speed they feel is <br /> reasonable and safe. Setting a speed limit in this manner ensures that the posted speed <br /> limits are not dependent on the judgment of one or a few individuals. The only roadway <br /> segments that should be posted 5 mph below the 85% speed are those where unusual <br /> conditions exist or excessive speed-related accidents have occurred. <br /> Table 1 lists the roadway segment for which staff recommends a speed limit change. <br /> This change takes into consideration the critical speed, accident data and any unusual <br /> conditions on the roadway segment. The California Vehicle Code does not allow radar <br /> enforcement on roadways where the speed limit is not based on the 85% speed. These <br /> roadways are identified by the Code as speed traps, and citations may not be upheld in <br /> court if issued based on an invalid speed limit. <br /> The FHWA produces a California Road System(CRS)Map that distinguishes local roads from non-local roads. <br /> 85%speed is also called the critical speed and represents the 85th fastest car out of 100 cars. This number is used to <br /> set speed limits. <br /> Page 2 of 4 <br />