Evaluation of an Experimental Transverse-Bar Pavement Marking Treatment on Freeway Curves

Researchers performed a before-and-after analysis of speeds to determine the short-term and long-term effectiveness of an experimental transverse-bar pavement marking treatment at the “Plainfield Curve” on I-43/94 in Milwaukee, Wisconsin. The experimental transverse pavement marking treatment was installed in both the northbound and southbound lanes in early September 2006 and each treatment section was 1,000 feet in length. Each treatment section consisted of a series of white transverse-bar markings that were installed with decreasing spacing between successive markings giving drivers’ the perception of increasing speed when driving through the section of markings, potentially causing drivers to slow down. Each individual marking was 18 inches in lateral width by 12 inches longitudinally. Speed data were collected for two weeks in late July 2006, again in September 2006 approximately one-week after the markings had been installed, and again in March 2007 approximately six-months after the markings had been installed. The researchers used analysis of variance to analyze the mean speeds for more than 43,000 5-minute intervals measured at three locations in each lane of the northbound and southbound directions. The results of the analysis suggest that the experimental transverse pavement marking treatment was effective at reducing curve speeds, especially shortly after installation. The marking treatment showed the greatest effects on speeds midway through the marking treatment section with approximately 1 to 4 mph reductions in mean speed observed between the before-and-after periods (both short-term and long-term). A lane-by-lane analysis showed that the marking treatment was most effective at reducing speeds in the shoulder and middle lanes, while speeds in the median lane were relatively unaffected. TRB 2008 Annual Meeting CD-ROM Paper revised from original submittal.