Research Helps Fuel Improvements in Road Safety
October 19, 2006
What does a safe road look like? Is a safe road one where vehicles, bicyclists, and pedestrians all share the same right-of-way without sidewalks or striped bike lanes? Are the shoulders paved or gravel? Are those shoulders 8 or 10 feet wide? Is it a divided roadway or is it undivided? How many driveways access the roadway in each mile? Are the driveways and intersecting streets controlled by traffic signals, stop signs, or roundabouts? How much do these elements affect roadway safety?
The answers to these questions, and many others like them, depend on the context of the roadway. The engineers, planners, and developers who design the roadway and establish zoning and land uses along it should understand the character of the facility, the needs the facility serves or will serve, the road’s users, and the community’s vision. An ideal approach integrates safety into all aspects of traffic and transportation engineering including long-range transportation plans, roadway design and operations, and roadway access to land uses.
Decisions regarding highway and roadway safety have historically been reactive, relying on crash histories to reveal high-crash locations. This process is evolving to one where decisions integrate an increasing number of quantifiable, objective performance measures. Research studies are being conducted to evaluate the effectiveness of different countermeasures (e.g., increasing or decreasing lane width, installing a roundabout, changing signal timing) and to develop predictive models (mathematical equations) to estimate the expected crash occurrence at a location based on its physical characteristics (e.g. number of approaches at an intersection, cross-section of a roadway, driveway density).
The increase in research with an emphasis on safety was sparked by legislation passed by the federal government. The Transportation Equity Act for the 21st Century (TEA – 21), enacted in June 1998, and Safe, Accountable, Flexible, Efficient, Transportation Equity Act: A Legacy for Users (SAFETEA-LU), enacted in August 2005, provide federal funding for roadway projects that improve safety. This legislation also requires all states to develop and implement a Strategic Highway Safety Plan (SHSP). The plans are assembled on an annual basis and identify a strategic approach to identify and address the locations with the most severe safety concerns. Each state’s SHSP must publicly identify the locations in the top 5%, develop a plan or set of countermeasures to improve the locations, and identify performance measures that will track the safety improvements at the location. Further, each state must implement the countermeasures and document their adherence to the SHSP.
The Transportation Research Board (TRB) is funding (and has funded) research projects to develop prediction models, analysis tools, and guidance on how to effectively use these tools. These projects include:
- The National Cooperative Highway Research Program (NCHRP) 500 series;
- The Signalized Intersections guidebook;
- NCHRP 3-65 (Applying Modern Roundabouts in the U.S.);
- The upcoming Road Safety Audit guidebook;
- The Highway Safety Manual (HSM); anticipated release 2008.
Software programs are also being developed. The capabilities of these programs range from data collection, screening, diagnosis, and economic appraisals to evaluating the effectiveness of a countermeasure. The available guidebooks and software provide a variety of resources and tools to address safety at different phases of a project’s lifecycle and across different project types. The industry’s proactive approach to road safety, research projects, and more effective and reliable analysis tools, meld together to heighten the level of safety experienced by all road users.