During construction projects, it is often necessary to implement lane shifts in order to detour traffic around work zones or establish a new alignment. Shifting lanes requires obscuring or removing the existing pavement markings and applying new markings along the new alignment. The Manual on Uniform Traffic Control Devices (MUTCD) requires that all visible traces of the existing marking be removed or obliterated, and it does not allow for removal methods that will cause unacceptable scarring of the pavement. However, there is no specification for a level of scarring that is acceptable. Among the primary requirements of pavement marking systems is to create a durable, strongly bonded material. Pavement markings have to be capable of withstanding several years of wear due to heavy traffic at highway speeds and resist the environment (UV exposure, freeze/thaw, chemicals, etc.). Many of the new systems are epoxy-based and adhere adamantly to the pavement. Black tapes that are applied to obscure the existing markings tend not to last long enough and/or have different reflective properties than the pavement and may confuse drivers as to the correct path to follow. The problem may be exacerbated at night and in wet weather. Chemical systems that are aggressive enough to remove epoxies and other products may raise safety and environmental concerns. As a result, removal generally requires grinding of the markings, which leaves undesirable scarring that is often mistaken for actual pavement markings under low-light or wet conditions. Consequently, the owners of public highways are faced with a very difficult problem.
The objective of this research is to determine best practices for the safe, cost-effective, and environmentally acceptable removal of work zone and permanent pavement markings with minimal damage to the underlying pavement or visible character of the surface course. Questions to be answered include the following:
1. Are there chemical removal systems (perhaps organic, like citrus-based bituminous solvents) that are environmentally acceptable?
2. Are there mechanical processes, such as a combination of heat and power tools, that can effectively remove the markings?
3. Are there methods of applying a durable coating over the existing pavement marking that will blend in to the appearance of the pavement, perhaps by using color matching technology? Or can the full width of the pavement be covered completely in a cost-effective manner without losing friction characteristics?
4. How much removal is adequate to meet the MUTCD requirements?
5. How much tolerance is there for altering the pavement surface?
6. Is the removal technique of a reasonable cost for materials, equipment, and labor?
The final report was published as NCHRP Report 759 and is available here