Roadway Departure Countermeasures
The FHWA’s Roadway Departure Safety Program provides important information for transportation practitioners, decision makers, and others to assist them in preventing and reducing the severity of roadway departure crashes.
Roadway departure crashes are frequently severe and account for the majority of highway fatalities. In 2009, there were 16,265 fatal roadway departure crashes resulting in 18,087 fatalities, which was 53 percent of the fatal crashes in the United States. A roadway departure crash is defined as a non-intersection crash which occurs after a vehicle crosses an edge line or a center line, or otherwise leaves the traveled way.
Identifying road segments and the selecting appropriate, effective countermeasures becomes a critical part of the roadway safety improvement program to reduce crashes on the nation’s roadways.
Federal Highway Administration - Office of Safety recently developed the following twelve Safety countermeasures flyers that aim to provide needed information and available resources for use by State and local agencies, Safety advocates and practitioners as well as design professionals. These Flyers can also be downloaded as handouts in PDF format for distribution. If additional information is needed, please contact John Dewar – John.firstname.lastname@example.org or Joseph Cheung - Joseph.email@example.com.
Breakaway Features for Sign Supports, Utility Poles and Other Roadside Features
Breakaway devices are designed and constructed to break or yield when struck by a vehicle. The term “breakaway” refers to crash-tested devices that break or bend upon impact.
Bridge railings differ from other longitudinal roadside barriers because they are physically connected to the bridge structure, and are not usually designed to deflect when struck by a vehicle. Bridge railings are very important components of roadway safety systems and play an important role in preventing and mitigating crashes.
Many States are installing cable median barriers in locations where there is a high potential for crossover crashes. Studies in Washington State and North Carolina have shown substantial reduction in fatal and injury crashes compared to other types of median barriers.
Designed to redirect, slow, or stop an errant vehicle from causing a more severe crash, crashworthy concrete barriers come in a variety of shapes and heights that affect crash performance. The crash performance of barriers also depends on the type of vehicle, speed, and other variables.
Manual for Assessing Safety Hardware (MASH)
The AASHTO Manual for Assessing Safety Hardware (MASH) is the new state of the practice for the crash testing of safety hardware devices for use on the National Highway System (NHS). It updates and replaces NCHRP Report 350.
Median barriers are longitudinal barriers most commonly used to separate opposing directions of traffic on a divided highway. While these systems may not reduce the frequency of crashes due to roadway departure, they can definitely help prevent a median crash from becoming a median crossover head-on collision.
Recent research on standard 27-inch strong steel-post W-beam guardrail shows that it does not meet NCHRP Report 350 Test Level 3 criteria. FHWA recommends 31-inch height for all new installations of guardrail.
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.
Sign Retroreflectivity Requirements
The sheeting used on traffic signs is “retroreflective,” meaning it is designed so that light bounces back from the sign to enable nighttime visibility. Over time, the sign sheeting degrades. The FHWA standard, which is contained in the Manual on Uniform Traffic Control Devices (MUTCD), establishes minimum levels of sign retroreflectivity.
Rumble Strips & Rumble Stripes
More than half (53 percent) of U.S. fatal crashes occur after a driver crosses the edge or centerline of a roadway. Two-thirds (67 percent) of these fatal crashes occur in rural areas.
Horizontal Curve Safety
Horizontal curves are changes in the alignment or direction of the road, as opposed to vertical curves, which are a change in the slope. In 2008, more than 27 percent of fatal crashes occurred at horizontal curves; the vast majority (over 80 percent) were roadway departures. Due to the predominance of horizontal curves on typical rural roads, a higher percentage of fatal curve-related crashes occur on rural roads, particularly on two-lane roadways in rural areas. Fatality rates on rural roads are typically more than twice the rate than on urban roads, because of a number of infrastructure and non-infrastructure related issues.
Clear Zones and Roadside Terrain
A clear zone is an unobstructed, traversable roadside area designed to enable a driver to stop safely or regain control of a vehicle that has accidentally left the roadway. Clear zones are an effective strategy for prevention and mitigation of roadway departure crashes.
Safety Design Team Leader
Guidance memorandum on the Roadside Design Guide - 4th Edition NEW!
Memorandum - Roadside Safety Hardware-Federal-Aid Reimbursement Eligibility Process NEW!
2009 MUTCD Compliance Dates Revised NEW!
FHWA Technical Advisory T 5040.40: Center Line Rumble Strips NEW!
FHWA Memo: Technical Advisories for Rumble Strips NEW!
Roadway Departure Safety Implementation Plans
Roadway Departure Countermeasures
Roadside Design: Steel Strong Post W-beam. A guidance memo was issued on May 17, 2010 on the height of guardrail for new installations. Guidance regarding existing guardrail will be developed in the next several months, in consultation with AASHTO’s Technical Committee on Roadside Safety.
Pavement Marking Retroreflectivity Notice of Proposed Rulemaking [HTML, PDF]
MUTCD Text of the Proposed Pavement Marking Retroreflectivity Standard
Summary of the MUTCD Pavement Marking Retroreflectivity Standard
Revised Assessment of Economic Impacts of Pavement Marking Retroreflectivity
Low Cost Treatments for Horizontal Curve Safety
The Safety Edge