Institute for Transportation

About the research

This report analyzed the effects of portable changeable message signs (PCMS) on driver behavior in terms of speed characteristics using a driving simulator. Fifty-two participants from different age groups evaluated four messaging signs with text and number by driving through a virtual work zone. Driver reactions to the message signs were analyzed by examining drivers’ speed before and after each PCMS. It was observed that speeds did not vary significantly for the first seven intervals (defined before and after each PCMS). Significant difference, however, was found on the eighth interval before the start of the lane closure. A 70 mph highway served as the control scenario on which the mean speed of drivers was observed to be 62.55 mph. For the first message sign (MS-1) (Caution Work Zone Ahead: Reduce Speed Ahead) the mean speed of drivers decreased by 9.35 mph compared to the control scenario. For MS-2 (Speed Ahead 30 mph; 2 min to end of WZ), the mean speed reduced by 36.06 mph compared to the control scenario. For MS-3 (Prepare to stop; 4 min to end of WZ) a decrease of 39.46 mph was observed. For MS-4 (Prepare to stop; Stopped traffic ahead) a decrease of 48.91 mph was observed compared to the control scenario. Therefore, MS-4 showed the highest speed reduction compared to other messages. A participant survey was conducted to examine the drivers’ rating of the message signs. From this subjective evaluation, MS-2 was rated as the most effective as it was specific in terms of the anticipated speed ahead indicated and hence easier for drivers to follow.