Road markings that clearly define traffic lanes are critical to reducing accidents and improving driver safety. Road marking configurations—primarily the width and length of lines and the spacing between dashed lines—vary from state to state. The project identified driver preferences for road marking patterns and widths that can improve visibility and safety.
The visibility of road markings is critical to driver safety. Federal policy provides guidelines for the size of road markings, with the standard width of lane markings being 4 to 6 inches.
While Minnesota currently has a minimum center and stripe width of 4 inches and a minimum edge width of 6 inches, many states have begun using 6-inch widths for all markings, citing studies showing it is safer. Additionally, the spacing between medians on Minnesota roads does not meet current federal standards. These issues highlight the need for the Minnesota Department of Transportation to review its pavement marking policies.
”This project will help determine the size and spacing of pavement markings that are needed on Minnesota roadways,” said Ethan Peterson, a pavement marking and collision avoidance engineer with the Minnesota Department of Transportation’s Traffic Engineering Division. “This will help improve driver safety and comfort.”
The purpose of this study was to investigate driver preferences for road marking patterns, sizes, and contrast through a human factors study conducted on Minnesota roads. In addition, this study collected data on machine vision technologies used in autonomous vehicles that have been evaluated in previous studies.
Fifty-six participants with valid driver’s licenses drove vehicles equipped with instruments on 11 sections of study roads with different road marking configurations. The differences between these configurations are as follows:
Drivers rated different road markings based on their visibility and preference on a scale of 1 to 5, with 1 being the lowest or least desirable visibility and 5 being the highest or most desirable visibility. Cameras on the vehicle track the vehicle’s position relative to the dotted road markings as it moves.
After the test drive, drivers filled out a questionnaire indicating their preferences or dislikes regarding the road marking configurations. Drivers also gave an overall assessment of the road markings, made suggestions for possible improvements to improve daytime and nighttime visibility, and provided their understanding of the meaning or purpose of using black markings in combination with white markings.
Drivers’ favorite lane markings are 6 inches wide, 12.5 feet long, and spaced 37.5 feet apart. Other popular choices are 6-inch wide lanes spaced 20-30 feet apart and 15-25 feet apart. The current Minnesota Department of Transportation standard is 4-inch wide, 10-foot long lanes spaced 40 feet apart, which is one of the lowest-rated configurations. Survey results also showed that people prefer 6-inch lane markings over 4-inch lane markings.
The study group recommends that the Minnesota Department of Transportation change its policy from the current 10-foot-wide lane pattern spaced 40 feet apart to a pattern of 12.5-foot-long dashed lines spaced 37.5 feet apart. This pattern is more visible, more popular with drivers, and maintains the current 50-foot lane width set by the Minnesota Department of Transportation.
Some, but not all, participants enjoyed comparing the reticles and understood their value. The results also showed that participants had no preference for the style of contrast markings. Contrast markings are recommended for use in areas where the contrast between road markings and the road surface is low.
The Minnesota Department of Transportation incorporates the project’s recommendations for 6-inch-wide, 12.5-foot-long, 37.5-foot-spaced stripes into its guidelines, including the Minnesota Department of Transportation Traffic Management Manual, the Minnesota Department of Transportation Pavement Marking Manual, and the Minnesota Department of Transportation Pavement Marking Guide. These dimensions will become the standard for pavement markings on new and reconstructed Minnesota roads beginning in 2026.
Additionally, the Minnesota Department of Transportation (MnDOT) will begin using a lagging contrast pattern (white before black) on light-colored concrete pavement. Immediately following the white line will be a 10- or 12.5-foot-long black stripe. While the project found no conclusive evidence for the use of black stripes, related MnDOT studies have demonstrated their benefits.
Post time: May-22-2025