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• <br />• <br />• <br />What are the Legal Speed Limits? <br />MN Statute 169.14 <br />Speed laws are created for the protection of <br />the public and the curbing of unreasonable <br />behavior. To effectively enforce a law, the <br />public must believe that the law is <br />reasonable. Minnesota's speed regulations are based on the <br />same Basic Speed Law that is used in all 50 states: "No <br />person shall drive a vehicle on a highway at a speed greater <br />than is reasonable and prudent under the conditions ". <br />Statutory limits are based on the concept that uniform <br />categories of highways can operate safely at certain preset <br />maximum speeds under ideal conditions. Whether the speed <br />limit is posted or unposted, drivers are required to reduce <br />speed below these values for poor weather conditions, curves <br />or hills and potential hazards such as pedestrians. Drivers <br />must also reduce speed when approaching or passing <br />emergency vehicles with emergency lights flashing. <br />These are the most common statutory speeds: <br />▪ 10 mph in alleys <br />J 30 mph on streets in urban districts <br />J 70 mph on rural interstate highways <br />J 65 mph on urban interstate highways <br />J 65 mph on expressways <br />55 mph on other roads <br />Whenever these statutory speed limits are not the correct <br />value for a specific highway, the commissioner of <br />transportation authorizes the posting of other regulatory <br />speed limits. <br />Interstates are high design multi -lane divided highways <br />that have controlled access interchanges such as cloverleafs <br />or diamond shaped interchanges. Through traffic on the <br />interstate never has to stop or yield. Examples: 1 -94 or 1 -35 <br />Expressways are multi -lane divided highways but they <br />have entries and intersections, sometimes controlled by <br />traffic signals. Some interchanges may exist but they are <br />not the rule. Examples: Highway 10 or Highway 52 <br />Holt' Does Mn /DOT <br />Deterrrurle the Re'I11atory Speed Limit? <br />The commissioner of transportation sets regulatory speed <br />limits on state and local roads based on a thorough <br />engineering and traffic investigation. <br />These factors are considered: <br />J road type and condition <br />j location and type of access points (intersections, <br />entrances, etc.) <br />j sufficient length of roadway (1/4 mile minimum) <br />J existing traffic control devices (signs, signals, etc.) <br />. crash history <br />j traffic volume <br />j sight distances (curve, hill, etc.) <br />j test drive results <br />. speed study <br />The most important part of the traffic investigation is the <br />speed study. When choosing a speed, drivers take many <br />roadway environment factors into consideration. Therefore, <br />the speed that the majority of people consider prudent is an <br />important value. Data is collected by performing radar <br />checks at selected locations on the roadway under ideal <br />driving conditions. A technical analysis is done on the results <br />to determine the 85th percentile. This is the value indicating <br />the speed at which most (85 %) drivers are traveling under. <br />Experience has shown that a posted speed limit near this <br />value is the maximum safe and reasonable speed. Studies <br />have shown that traveling much faster or slower than this <br />value can increase your chance of being in a crash. <br />Engineering judgement is an important tool. The traffic <br />investigator must use knowledge of nationally accepted <br />principles combined with experience to assign the safe speed. <br />. NESori <br />August 2002 <br />Minnesota Department of Transportati <br />1 on <br />Office of Traffic Engineering & <br />Intelligent Transportation Systems <br />www.dot.state.mn.us /trafficeng <br />/Awing Miasma <br />