Nighttime Visibility

Methods for Maintaining Pavement Marking Retroreflectivity

CHAPTER 7. BLANKET REPLACEMENT METHOD

Introduction

The blanket replacement method is essentially a version of service life method, but rather than being executed for each pavement marking, it is executed on a larger spatial or strategic basis. In this method all pavement markings of a certain type or within a certain corridor are replaced at specific intervals. Using this method, the agency does not need to assess the visibility of pavement markings or track all pavement marking installations. It is, however, necessary to record the date of each replacement cycle so that a transportation agency can determine when to repeat the process.

This method should only be used where agencies have historical data or research findings showing the life of their longitudinally applied in-service pavement markings as a function of key variables such as pavement marking system, pavement surface type, and traffic volumes. The service life data should be available to support the service life estimates.

Procedures

The following factors apply to the use of this procedure:

• The replacement cycle is based on the expected service life of the markings given factors such as the marking type, surface type of the roadway, and traffic volume.
• Replacement zones can be based on an area, corridor, or pavement marking type (e.g., edge line, center line, and lane line).
• All markings within the replacement zone are replaced as they near the end of the cycle regardless of the condition of the marking.

Current Practice

Several State transportation agencies use the blanket replacement method to manage pavement marking retroreflectivity. Among them are New Hampshire, Alaska, and Maine. In New Hampshire and Maine, all the highways are restriped each summer with a waterborne paint. In Alaska, all roadways without a durable striping product are re-striped annually with low-VOC paint. Some agencies even restripe with paint twice per year because for them it is the most cost effective way to maintain their markings.

A literature review and agency surveys have shown that the expected service life of pavement markings varies considerably across the United States.(24) The range of values for assorted pavement marking types is shown in Table 3. Caution should be exercised in using the values shown in Table 3 as these are based on research reports, telephone interviews, and reviews of State transportation agency websites. In some instances, data were only from one State. In other cases, the range represents data from several States.

Table 2. Range of pavement marking service life estimates.⁽²⁵⁾

Linking Blanket Replacement to Minimum Retroreflectivity Levels

The minimum retroreflectivity levels provide the initial basis for the expected life criteria, but an understanding of the actual degradation rates of in-service pavement markings is required to set appropriate triggers as retroreflectivity levels approach the minimum requirements. Under this method, retroreflectivity levels of pavement markings are not assessed in the field, and opportunities for capturing data that may be useful in adjusting service lives, trigger points, or maintenance strategies are limited.

Advantages

The major benefit of using this method is that there is no need to conduct field inspections once the service life estimates are generated. However, the key drawback is that a management system needs to be implemented so that the installation and replacement cycles can be properly administered.

For agencies with heavy winter maintenance activities that make annually striping their entire network a necessity, this method can be quite effective. Many northern agencies currently practice this maintenance method–restriping certain highway systems each year with waterborne paint. However, these agencies need to prioritize their restriping programs so that they bring their markings up to the minimum retroreflectivity levels as soon as practical after winter conditions.

Concerns

One of the issues with this method is that the replacement times can vary depending on the marking type, pavement surface type and condition, and traffic volumes. Having reliable service life numbers is important for obtaining the maximum benefit from this method. In addition, regional climate plays a critical role in the expected service life. Having local or regional service life data is important.

To use this method with durable markings, an agency has to have many years of in-service pavement marking retroreflectivity data available to estimate the life of the markings based on factors such as the pavement markings type, the pavement surface, and the traffic volume. Many agencies have conducted in-house test decks or contracted with researchers to design and monitor test decks. These types of activities are time consuming but essential in order to properly estimate the service life of durable pavement markings.

⁽²⁴⁾Migletz, J. and J. Graham, NCHRP Synthesis 306: Long-Term Pavement Marking Practices, (Washington, D.C.: Transportation Research Board, 2002).

⁽²⁵⁾ Federal Highway Administration, "Report on Economic Impact of Implementing Minimum Pavement Marking Retroreflectivity Rule-Making." Posted in the SNPA Docket Comment