Below are several research documents that you may find useful in learning more about pavement marking safety issues, including retroreflectivity.

• Synthesis of Pavement Marking Research [HTML, PDF 2.22 MB]
  This 2015 report summarizes recent research on longitudinal pavement markings.

• An Investigation of Longitudinal Pavement Marking Retroreflectivity and Safety
  This 2013 study analyzes crash data along with measured and imputed retroreflectivity data.  It supports a positive safety effect of maintaining retroreflectivity of pavement markings.

• Safety Effects of Wide Edge Lines – see Chapter 4 of "Pavement Marking Demonstration Projects: State of Alaska and State of Tennessee" [HTML, PDF]
  This 2013 retrospective study includes six total crash analyses based on the available data from Illinois, Kansas and Michigan. Consolidated results indicate that wider edge lines are effective in reducing several types of non-winter crashes on rural two-lane highways.

• Operational Effects of Wide Edge Lines – see Chapter 3 of "Pavement Marking Demonstration Projects: State of Alaska and State of Tennessee" [HTML, PDF]
  This 2013 horizontal curve study in Tennessee produced similar findings to previous research, with mixed results indicating a net zero impact in terms of vehicle lateral placement and speed.

• NCHRP Project 20-07 Task 310: Determination of Current Levels of Retroreflectance Attained and Maintained by the State Departments of Transportation
  This 2013 research study collected and analyzed retroreflectivity levels of a sample of pavement markings in nine states to get a feel for the current state of the practice in regard to retroreflectivity levels of pavement markings both before and after winter maintenance.

• Pavement Marking Retroreflectivity Workshops Summary Report [PDF]
  This 2008 report summarizes input received during two pavement marking retroreflectivity workshops sponsored by the FHWA in 2007 to gather stakeholder input for the proposed revisions to the Manual on Uniform Traffic Control Devices (MUTCD)regarding pavement marking retroreflectivity. [Publication No. FHWA-SA-08-003]

• The Benefits of Pavement Markings: A Renewed Perspective Based on Recent and Ongoing Research: [HTML, PDF]
  This 2008 paper was developed to bring together many of the recent and ongoing research efforts to demonstrate a renewed perspective regarding the benefits of pavement markings and, where information is available, describe the benefits of various aspects of pavement markings. Published in Transportation Research Record TRR 2107.

• Updates to Research on Recommended Minimum Levels for Pavement Marking Retroreflectivity to Meet Driver Night Visibility Needs [HTML, PDF 659 KB]
  This 2007 research report presents new recommendations for minimum levels for pavement marketing reflectivity. The report also presents an analysis of the limitations of the recommendations, and a plan for future research. [Publication No. FHWA-HRT-07-059]

• Impact of Edge Lines on Safety of Rural Two-Lane Highways:
  This 2005 before-and-after study of edge line implementation in Louisiana showed that edge lines help drivers confine their traveling path, particularly at night, and edge lines have no or little effect on drivers' speed.

• Roadway Delineation Practices Handbook:
  This 1994 FHWA handbook was developed to assist design, traffic and maintenance engineering personnel in making determinations about roadway delineation systems. Topics covered include how to choose the appropriate system for a given situation; when a system has reached the end of its useful life; and how to maintain a quality delineation system.

• Benefit-Cost Analysis of Lane Marking [PDF 1.74 MB]
  Pavement markings save lives and reduce congestion. This analysis of the benefits and costs of edge lines, center lines, and lane lines concludes that, on average, each dollar spent on pavement striping yields $60 in benefits. The benefit-cost ratio rises with traffic volume. The urban ratio is twice the rural ratio. Published in 1992, Transportation Research Record 1334.

Other Research

• Safety Evaluation of Wet-Reflective Pavement Markings [HTML, PDF]
  This 2015 safety evaluation of pavement marking products marketed as wet-retroreflective indicates potential crash reductions. As with any crash modification factor, these should be applied only to the types of crashes included in the research. Note that the study did not indicate the retroreflectivity levels or age of the markings included in the study.

For information about traffic control devices and the Manual on Uniform Traffic Control Devices (MUTCD), other than visibility or retroreflectivity, please see FHWA's MUTCD website