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Roadway departure crashes account for the majority of roadway fatalities, and many of them occur on wet pavements. 70% of wet pavement crashes can be prevented or minimized by improving pavement friction.
In 2008, more than 19,000 people were killed in roadway departure crashes in the United States. Poor roadway conditions, especially wet pavement, has been identified as a major contributing factor in roadway departure crashes.
Current Federal Highway Administration (FHWA) policies regarding pavement are as follows:
Further, research conducted by the National Transportation Safety Board and FHWA indicates that about 70% of wet pavement crashes can be prevented or minimized by improved pavement friction.
FHWA Guidance on Pavement Friction Management
The current technical advisory issued by FHWA on June 17, 2010, Pavement Friction Management (T 5040.38), provides guidance to State and local highway agencies on managing pavement surface friction on roadways. This advisory supersedes the 1980 FHWA Technical Advisory 5040.17, Skid Accident Reduction Program.
This technical advisory also covers topics such as: test equipment for measuring pavement friction; the identification and classification of roadway locations with elevated crash rates; how to prioritize projects for improving pavement friction; the appropriate frequency and extent of friction testing on a highway network; and how to determine a pavement friction management program's effectiveness. Additional reference materials on pavement friction management and measurement are highlighted as well.
Purpose of a Friction Management Program
The main purpose of a pavement friction management program is to minimize friction-related vehicle crashes by:
Key Components of a Friction Management Program
Pavement friction management includes engineering practices to provide surfaces with adequate and durable friction properties plus data collection and analysis to ensure the effectiveness of the engineering practices. The most effective data collection and analysis components of friction management programs use pavement friction and friction-related data, crash data, and traffic data to:
Pavement Friction Program Examples
The New York State DOT (NYSDOT) implemented a program to identify sites statewide with a low skid resistance and treat them with overlays as part of their maintenance program. A site is eligible for treatment if its 2-year wet accident proportion is 50% higher than the average wet crash proportion for roads in the same county. Between 1995 and 1997, NYSDOT treated 36 sites, which reduced the annually recurring wet road crashes by more than 800. These results, and others throughout the State, support earlier findings that treating wet-road crash locations can reduce this type of crash by 50% and reduce total crashes by 20%.
The Florida DOT (FDOT) treated a curved freeway ramp with Tyregrip®, a high-friction material consisting of a highly modified exothermic epoxy resin dressed with a calcinated bauxite with a Polish Stone Value of 70%+. This treatment proved effective at increasing the skid resistance value from 35 to 104. While the FDOT application was on a freeway ramp, the material may also be applicable to a higher volume curve with a higher than normal number of wet pavement crashes. The treatment type and product example provided above does not imply validation or endorsement by the FHWA Office of Safety; several products and materials are available and should be considered to improve pavement friction.
For More Information
FHWA's Pavement Friction Management Technical Advisory at www.fhwa.dot.gov/pavement/t504038.cfm
Guide for Pavement Friction NCHRP Project 1-43 at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rrd_321.pdf
Evaluation of Pavement Friction Characteristics NCHRP SYNTHESIS 291 at http://pubsindex.trb.org/view.aspx?id=675639
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