Rochester Today: How Speed Limits Are Determined

Have you ever wondered how the Minnesota Department of Transportation sets speed limits?  MNDOT Mike (Dougherty) brought one of the agency's traffic engineers with him for his regular appearance on Rochester Today with Tracy McCray and Andy Brownell.

Nancy Klema came to the KROC-AM studio in downtown Rochester and spent the hour explaining the process used to set speed limits and discussing other engineering methods used by the Transportation Department to make Minnesota roads safer. She explained state law mandates the limits be set at 30, 55, 65 and 70 miles per hour in many areas, but MNDOT has some discretion in others.

In those cases, MNDOT employees will use the same radar guns utilized by law enforcement to monitor the speeds of motorists passing by and then set the limit at the 85th percentile of those speeds. Klema says the method is based on studies that show the majority of drivers will choose speeds that are safe for the conditions.

Click on the play button below to hear the entire show.