Our nation’s roadways have many retroreflective devices integrated into their delineation systems to deliver needed visual clues to the motorist. Luminance, contrast, color, placement and the physical condition of the device are other factors that come into play to either enhance or degrade the visibility and legibility of the device.
Although the estimated cost to maintain these important traffic control devices seems an expensive proposition, the cost not to maintain them is likely to be even more expensive. With the loss of life on our highways at over 40,000 people per year and economic losses at about $1 million per life, any reduction in fatalities would be a long-term investment in roadway safety dollars.
Currently the MUTCD requires that all signs and pavement marking be visible at night, via retroreflectivity or ambient illumination. New requirements would actually require a retroreflective value be maintained and the traffic control device replaced when it falls below that level. A brief synopsis follows as to how the Federal Highway Administration (FHWA) arrived at minimum in-service replacement levels.
Sign reading
To develop minimum requirements for signs, the FHWA conducted research to address retroreflectivity performance issues. This research identified a range of minimum levels of retroreflectivity for the signs, created a sign management system and developed strategies for state and local agencies to comply with these guidelines in a cost-effective manner.
The four groups of warning, regulatory and guide signs evaluated were:
• Yellow or orange background and black legend;
• White legend on red background;
• Black or black and red legend on white background; and
• White legend on green background.
A Computer Analysis of Retroreflective Traffic Sign (CARTS) model was developed to measure the Minimum Required Visibility Distance (MRVD) of these signs. The CARTS model accounted for factors such as sign type, size and location. Also included in the model were: headlamp design of the car and driver position, driver age and visual characteristics and roadway design and traffic levels. Using the CARTS model, independent researchers developed and proposed minimum sign retroreflectivity guidelines to the FHWA.
Many state and local transportation agencies are concerned about the cost to implement new retroreflectivity regulations. An FHWA report, “Impacts on State and Local Agencies for Maintaining Traffic Signs within Minimum Retroreflectivity Guidelines,” estimates replacement costs for states at $32 million and for local agencies at $144 million. Agencies also are fearful of liability issues that may arise from claims that signs don’t meet requirements.
Pavement markings
The FHWA conducted field evaluations to develop minimum retroreflectivity requirements for pavement markings. Thirty-two state and local agencies agreed to participate in the study evaluating a variety of pavement marking materials and roadway types.
A second study utilized the Computer Aided Road Marking Visibility Evaluator (CARVE) to determine the amount of retroreflectivity required to support driver performance.
They make the rules
With research analysis and recommendations in hand, the FHWA was preparing to issue a Notice of Proposed Rulemaking (NPRM) to insert language into the MUTCD requiring minimum levels of retroreflectivity for pavement markings and signs.
The American Association of State Highway & Transportation Officials (AASHTO) requested that the FHWA delay the issuance of the NPRM until they could study the research results. The AASHTO Standing Committee on Highways (SCOH) formed a task group to look at the proposed rulemaking and its potential impact on transportation agencies. AASHTO members felt development of a formal position and resolution on the issue was needed.
After several conference calls, the task force scheduled a meeting in Washington, D.C., to further develop its charge. Due to the magnitude of the issue, the task force formed four subgroups to assess sign and pavement marking criteria as well as measurement and implementation concerns. This task force is committed to a six-month time frame in which to deliver a formal report to the SCOH and forwarding this on to the FHWA during their meeting early in October 1999.
The FHWA is also scheduling invitation-only workshops for state and local agencies to assist them in understanding and preparing to meet the challenges posed by new requirements. The FHWA anticipates releasing the NPRM for signs by March 2000 and pavement markings by December 2000.
In order to keep ATSSA members current on this important issue, a special briefing will be held during the ATSSA Midyear Meeting in Nashville on Aug. 13. Members will be briefed on the NPRM process and how changes will affect their businesses.
