Can the speed limit on my street be lowered?
March 6, 2020
Operating speeds are based on the visual scene and characteristics of the roadway more than by the posted speed limit. As a result, changes in the posted speed limit have little to no effect on vehicle speeds. A nationwide study collected speed data from 100 sites across 22 states where posted speed limits were either raised or lowered by increments of 5 mph. Review of the before and after speed data revealed that changes in speed were generally 2 miles per hour. Changing the posted speed limit did not have a significant effect on modifying driver behavior.
All roads in Truckee are categorized as local roads per the California Vehicle Code definition. The speed limit is set at 25 MPH (Town Municipal Code 10.05.020 Town Prima Facie Speed) for most roads in Truckee unless a higher speed limit is determined to be appropriate. Under this circumstance, the Town typically establishes speed limits based on the 85th percentile speeds which is the speed that 85 percent of vehicles are traveling at or below. The 85th percentile speed is used because it reflects a collective judgment of the vast majority of drivers as to a reasonable speed for given roadway conditions. Considerations are also made with regard to infrastructure and traffic conditions, such as: roadway pavement widths, shoulder widths, curves, driveway density, potential for and volume of bicycle and pedestrian traffic, and collision rates. Lowering a speed limit below the 85th percentile speed does not necessarily improve safety or result in voluntary motorist compliance.