What are the Legal Speed Limits
Minnesota State Statute 169.14
Speed laws are created for the protection of the public and the curbing of unreasonable behavior.
To effectively enforce a law, the public 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.”
Statutory speed limits are based on the concept that uniform categories of highways can operate safely at certain preset maximum speeds under ideal conditions. Whether the speed limit is posted or unposted, drivers are required to reduce speed below these values for poor weather conditions, curves or hills and potential hazards such as pedestrians. Drivers must also reduce speed when approaching or passing emergency vehicles with emergency lights flashing.
The most common statutory speeds 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 roads.
Whenever these statutory speed limits are not the correct value for a specific highway, the commissioner of transportation authorizes the posting of other regulatory speed limits.
How are speed limits set?
The Commissioner of Transportation sets regulatory speed limits on state and local roads based on a thorough engineering and traffic investigation.
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 (curves, hills, etc.)
- Test drive results
- Speed study.
The most important part of the traffic investigation is the speed study. When choosing a speed, drivers take many roadway environment factors into consideration. Therefore, the speed that the majority of people consider prudent is an important value. Data is collected by performing radar checks at selected locations on the roadway under ideal driving conditions. A technical analysis is done on the results to determine the 85th percentile. This is the value indicating the speed at which most (85%) drivers are traveling under. Experience has shown that a posted speed limit near this value is the maximum safe and reasonable speed. Studies have shown that traveling much faster or slower than this value can increase your chance of being in a crash.
Engineering judgment is an important tool. The traffic investigator must use knowledge of nationally accepted principles combined with experience to assign the safe speed.