The research conducted under this project identified the benefits, costs, drawbacks, and implementation issues of switching from the present two-color pavement marking system to an all-white pavement marking system.

The use of yellow and white pavement markings has been the subject of debate for transportation agencies since the 1920s. In 1971, the Manual on Uniform Traffic Control Devices first specified that yellow markings would be used to separate traffic traveling in opposite directions. However, it is uncertain whether most U.S. drivers understand or appreciate the significance of the current system.

Several concerns are associated with the use of yellow pavement markings. A major concern is that they are 30 percent less bright (on average) than their white counterparts. Brighter markings provide improved guidance during darkness and inclement weather and may enhance the safety of our roadway system, especially for the aging population. With the development of minimum retroreflectivity guidelines by FHWA nearing completion, the continued use of yellow markings may create a difficult situation for transportation agencies responsible for maintaining the roadway markings. Yellow markings are more expensive to manufacture, and having a two-color marking system increases the cost of inventory, equipment, and application. Although manufacturers have worked to eliminate the use of lead and other heavy metals from yellow marking materials, in some cases, these environmentally hazardous ingredients are still being used. However, when these ingredients have been eliminated, this modification has adversely affected nighttime color rendition.

The findings of the study are documented in NCHRP Report 484, Feasibility Study for an All-White Pavement Marking System. This report provides a full description of the research performed under this project. The primary recommendation is that an all-white pavement marking system not be implemented in the United States at the present time. The researchers also identified several actions that should be taken to improve the current yellow-white marking system.