06-05-2017 Council Packet - Laserfiche WebLink

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What are the legal speed limits?How does MnDOT determine the speed limit? What are the types of speed limits? State law says every road should have a speed limit, whether posted or not. Speed limits are set according to Minnesota State Statute 169.14. The Minnesota Department of Transportation carries out state laws through the development and enforcement of regulations.Speed limits are set to improve traffic flow and reduce crashes, injuries and fatalities and the costs associated with them. Speed limits are also intended to supplement motorists’ judgment in determining speeds. To effectively enforce a law, motorists must believe that the law is reasonable. Minnesota’s speed regulations are based on the same basic speed law that is used in all 50 states: “No person shall drive a vehicle on a highway at a speed greater than is reasonable and prudent under the conditions.”Speed limits are based on the concept that highways can operate safely at set maximum speeds under ideal conditions. In poor weather conditions, at curves or hills and when there are potential hazards such as pedestrians, drivers are required to reduce speeds below the speed limits, whether they are posted or not. Drivers must also reduce speed when approaching or passing emergency vehicles with emergency lights flashing. These factors are considered: ◉ Road type and condition ◉ Location and type of access points (intersections, entrances, etc.) ◉ Sufficient length of roadway (1/4 mile minimum) ◉ Existing traffic control devices (signs, signals, etc.) ◉ Crash history ◉ Traffic volume ◉ Sight distances (curve, hill, etc.) ◉ Test drive results ◉ Speed study REGULATORY SPEED LIMIT SIGN This black and white sign shows the maximum speed that motorist may travel under ideal conditions. It can be a value based on state statute or it must be authorized by the commissioner of transportation. ADVISORY SPEED SIGN This black and yellow speed sign is used to advise motorists of a comfortable speed to navigate certain situations. It is used with a warning sign. For example, when traveling on a winding road, the curve warning sign would be used with an advisory speed sign. This sign may be posted by the local road authority on local roads. SPEED LIMITS IN SCHOOL ZONES Local authorities may establish school speed limits on local streets, within a school zone, based on the engineering and traffic investigation as directed by the commissioner of transportation. This speed limit is in effect whenever children are present, such as before and after school or during recess. The school sign is black and yellow and the other signs are black and white. Optional fluorescent yellow green may be used for the school sign. SPEED LIMIT SCHOOL WHEN CHILDREN ARE PRESENT The most common speeds regulated by state law are: ◉ 10 mph in alleys ◉ 30 mph on streets in urban districts ◉ 70 mph on rural interstate highways ◉ 65 mph on urban interstate highways ◉ 65 mph on expressways ◉ 55 mph on other roadsWhen these speed limits are not the correct value for a specific highway, speed limits may be changed. The speed study is the most important part of the traffic investigation. Drivers take many roadway environment factors into consideration when choosing a speed. The speed that the majority of people consider reasonable is an important value. Data is collected by performing radar checks at selected locations on the roadway under ideal driving conditions.An analysis is done on the results to determine the 85th percentile, which is the value indicating the speed at which most (85%) drivers are traveling. The posted speed limit near the 85th percentile is the maximum safe and reasonable speed. Studies show that traveling faster or slower than this value can increase the chances of being in a crash.Engineering judgment is the most important tool. The traffic investigator must use knowledge of nationally accepted principles combined with experience to assign the safe speed. Interstates are high design multi-lane divided highways that have controlled access interchanges such as cloverleaf or diamond shaped interchanges. Through traffic on the interstate never has to stop or yield. Examples: I-94 or I-35 Expressways are multi-lane divided highways but they have entries and intersections, sometimes controlled by traffic signals. Some interchanges may exist but they are not the rule. Examples: Highways 10 or Highway 52