Speed Limit Policy

The Illinois Vehicle Code sets the maximum speed limit on local highways at 55 mph.  Limits can be set lower, especially within corporate limits and at other appropriate locations, but they cannot be set higher than 55 mph.  Even where rural highways are unposted, the maximum limit on local highways is still 55 mph.  Additionally, the Kendall County Board has the authority to set speed limits on both County and Township Highways, but not on municipal streets.

National research (NCHRP 17-76) was conducted and completed in 2021 to develop uniform recommendations for setting posted speed limits.  This research introduced new recommendations for implementing different percentile speeds and safety factors based on road type and roadway context/environment.  The research was used to help create IDOT’s – and thus, Kendall County’s – policy and procedures for altering statutory speeds.

IDOT’s new speed limits policy became effective in June 2025.  Shortly thereafter, Kendall County adopted IDOT’s Policy on Establishing and Posting Speed Limits on the State Highway System.  This action was taken, per IDOT’s recommendation, to provide consistency amongst local agencies, and to ensure compliance with federal regulations and state statutes.  Said policy seeks to take the emotion out of the decision to establish altered speed limits on County and Township Highways.  Instead, altered speed zones are established based on the road type, prevailing speed, and several other factors, including accident history, access control, pedestrian and bicycle activity, as well as on-street parking.

On township highways, Kendall County will not perform a speed study without a formal request from the Township Highway Commissioner.  For County Highways, speed studies may be initiated for various reasons, including, but not limited to, changing traffic volumes or accident history, elected official requests, or public input.  If a speed study reveals that an altered speed limit is warranted, the recommendation for altering the speed limit will be presented to the County Board for action.  If approved, the altered speed limit becomes enforceable upon erection of speed limit signs. 

Speed limits, both statutory and altered, are absolute in character, and no motorist may legally exceed such limits at any time, regardless of conditions.  Therefore, an altered speed limit shall reflect the optimum, rather than the adverse, driving condition, as drivers are subject to citation even though traveling at a speed lower than the posted limit if they are driving at a speed that is greater than is reasonable and proper with regard to traffic conditions and the use of the highway, or endangers the safety of any person or property.