Setting Speed Limits

Research conducted through a Transportation Research Board special committee has concluded that setting speed limits primarily on the basis of the commonly accepted “85th-percentile” speed may not be appropriate on roads in more urban areas with a variety of road users and high traffic volumes and roadside activity. This TRB special committee recommended that an expert system approach be developed to advise and assist transportation engineers and planners in setting appropriate speed limits.

Expert System for Recommending Speed Limits in Speed Zones - US LIMITS
HSRC researchers developed a system through the NCHRP Project 3-67, Expert System for Recommending Speed Limits in Speed Zones. "US LIMITS" is a knowledge-based, expert system to be used by traffic engineers to analyze specific segments of all types of roads, from rural local roads to urban freeways. knowledge-based expert system for recommending speed limits in speed zones that are considered to be credible and enforceable in the eyes of traffic engineers, politicians and policy makers, enforcement officials, judges and magistrates, and drivers.

For more information on this project, please visit