From the passage of the National Maximum Speed Limit (NMSL) of 55 mph in 1974 through its repeal in 1995 speed monitoring programs have been mandated by the federal government. The speed-monitoring program was primarily intended to provide reliable data to be included as a part of the State’s annual certification in order to be approved for Federal Aid highway projects. The repeal of the NMSL in 1995 not only authorized states to set their own speed limits, it also allowed states to develop their own speed monitoring programs. The goal of this research is to provide the framework for a speed-monitoring program to meet the needs of agencies and organizations that use speed-monitoring data in the State of Indiana. A proposed speed monitoring plan is developed which distributes speed monitoring stations to highway classes according to three primary criteria: spatial distribution, crash distribution, and distribution of daily vehicle miles traveled. The proposed speed-monitoring program will utilize 38 existing speed, weigh-in-motion, and automated traffic recording stations. The stations will be monitored four times a year for a 24-hour period. Furthermore, the proposed program will monitor speeds based on vehicle length. It is the recommendation of this research that Indiana phase in the proposed speed-monitoring plan developed in the present research, during the 1999 calendar year. The implementation should include a visual inspection of all the WIM, ATR, and speed monitoring stations listed in Appendix A to ensure they are still capable of monitoring speeds by vehicle class and travel direction. If any problems should arise with the existing stations, that station should be substituted for another station within that district and highway class.

Report Number



maximum speed limit, state highway network, Indiana, safety, productivity, SPR-2150

SPR Number


Project Number


File Number


Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

Date of this Version