Safety Evaluation of Profiled Thermoplastic Pavement Markings

Chapter 1. Introduction

This chapter presents background information on the strategy of using profiled thermoplastic pavement markings, the goals of the study reported here, and a review of the existing literature on the use of profiled thermoplastic pavement markings.

Background on Strategy

Although policies have varied by jurisdiction, most roadways with any significant volume of traffic have included edge lines, center lines, and—in the case of multilane roadways—lane lines. These markings provide guidance to drivers on the intended vehicle path.

The treatment of interest is the use of profiled thermoplastic pavement markings. This treatment provides a rumble effect and enhances visibility compared with standard lane markings, particularly at night and during wet conditions. Because snowplowing can destroy this marking, its use is typically limited to locations characterized by warmer climates.

According to the Federal Highway Administration (FHWA), several agencies have used the treatment with good results, but none have conducted a safety effectiveness evaluation.⁽¹⁾

There are two types of profiled markings—raised and inverted profile patterns—as shown in figure 1 and figure 2.

Background on Study

FHWA established the Development of Crash Modification Factors (DCMF) program in 2012 to address highway safety research needs for evaluating new and innovative safety strategies (improvements) by developing reliable quantitative estimates of their effectiveness in reducing crashes. The ultimate goal of the DCMF program is to save lives by identifying new safety strategies that effectively reduce crashes and to promote those strategies for nationwide implementation by providing measures of their safety effectiveness and B/C ratios through research. State transportation departments and other transportation agencies need objective measures for safety effectiveness and benefit–cost (B/C) ratios before investing in broad applications of new strategies for safety improvements. Forty State transportation departments have provided technical feedback on safety improvements to the DCMF program and have implemented new safety improvements to facilitate evaluations. These States are members of the Evaluation of Low-Cost Safety Improvements Pooled Fund Study (ELCSI-PFS), which functions under the DCMF program.

The use of profiled thermoplastic pavement markings was selected as a strategy to be evaluated as part of this effort.

Literature Review

A literature review found no published research evaluating the effect of profiled thermoplastic pavement markings on crashes. The following discussion of profiled thermoplastic pavement markings is a summary of the information provided in volume 4 of the National Cooperative Highway Research Program Report 500 Guides, which focused on center-line applications (in contrast to the States that provided data for this study and applied the profiled markings on edge lines).⁽²⁾

Profiled markings provide an audible/tactile effect, although it is less noticeable to drivers of larger vehicles, especially trucks. The effect is similar to that experienced when driving over raised pavement markers with short spacing. While the audible/tactile effect can be advantageous, its principal benefit is improved visibility at night, in particular during wet conditions, compared with standard pavement markings. The treatment would be limited to areas where there is little or no snow because snowplow blades will easily scrape off the markings.

As of the date of this study, the strategy had not been sufficiently evaluated to be considered proven, but there had been no significant findings of negative effects.

Application of profiled thermoplastic markings has been typically recommended under the following conditions for two-lane rural roads:

• Snow removal is not required.
• No-passing zones are relatively long.
• Volume levels and crash experience do not justify more costly treatments.
• Resurfacing or other pavement maintenance activities that would cause removal of the treatment are not scheduled for at least 3 years.
• The areas have higher than normal rainfall.
• These markings can be used as an incremental improvement when more cost-intensive projects are being designed and funded.

There have been no significant obstacles or difficulties in using this treatment, although its use may not be suitable for open-graded or seal-coated surfaces. No adverse effects have been reported for motorcycles.