U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Fatalities at rural road intersections account for approximately 40 percent of the national intersection related fatalities; more than 80 percent of these fatalities occur at unsignalized intersections. Local administrators, township managers, and public works officials who maintain and operate local rural roads should be engaged in intersection safety to identify intersections with safety issues and choose countermeasures to reduce the number and severity of intersection crashes.
To date, several States have completed Intersection Safety Implementation Plans with assistance from FHWA. These plans were developed to guide intersection safety implementation activities on State and local roads arising from the State Strategic Highway Safety Plans. The plans include the activities, countermeasures, strategies, deployment levels, implementation steps, and estimate of funds necessary to achieve intersection safety goals. The local road practitioners should consult their State's Intersection Safety Implementation Plan, if available, before embarking on an improvement strategy.
When seeking to address local rural road intersection safety, the local practitioners should consider which implementation approach to use. The three main approaches are systematic, spot location, and comprehensive. Availability and quality of intersection crash and roadway data, the number of locations to be addressed, and available funding are factors that may play a role in the selection of an implementation approach.
Determining the nature of the problems and their locations will assist in making the most informed decisions for countermeasure selection and implementation in addressing intersection safety issues. When conducting a safety analysis, a minimum of 3 years of crash data is desired to obtain an accurate picture of the intersection safety issues within a jurisdiction, since crashes are relatively rare events and are not universally distributed across all intersections. Due to the possibility of changes in traffic patterns and the roadway itself, data more than 5 years old are typically not desirable for assessing safety issues.
Analysis can range from simple "push pin" maps for identifying crash clusters to statistical analyses of crash rates, depending on the crash history and other available data. There are a number of information sources that can be used to identify crashes that are occurring at rural intersections; State and local crash databases, law enforcement crash reports and citations, observational information from road maintenance crews and law enforcement, and public notification of safety concerns.
Other variables to be considered when conducting analysis include crash location, date and time, crash type, crash severity, weather conditions, sequence of events, and contributing circumstances. In addition, roadway data and traffic volumes are factors to be considered when determining the intersection safety issues.
Regardless of the implementation approach chosen, a field review should be conducted at identified locations. Intersection field reviews have the potential to identify safety issues and solutions that cannot be determined by data analysis alone. Field reviews can be conducted as informal field assessments or as formal Road Safety Audits (RSAs). Decisions regarding which countermeasures to install to address a safety issue can be challenging. When appropriate, the local practitioner should seek engineering expertise from a State or local engineer or through the State Local Technical Assistance Program (LTAP). For a conventional unsignalized intersection, a typical enhancement of sign and pavement markings including double Stop signs, Stop Ahead signs and stop bars on the minor leg(s) of the intersection and intersection warning signs and appropriate pavement markings for the major leg(s) of the intersection should be considered. This installation is recommended for intersection locations that have experienced a high or moderate level of crashes. In addition, a high number of supplemental countermeasures are available for deployment based on crash history, location, and level of effectiveness.
Countermeasure assessment after implementation is important to the intersection safety program. This will inform the practitioner of the effectiveness of the strategy and if it should be applied to other locations. The most common methodology for the evaluation of a given countermeasure is the analysis of crash data before and after its installation. Three years of data after the installation is ideal for evaluation, however, changes in traffic volume and roadway information can also affect the outcome and should be taken into account during assessment. Local highway agencies have unique responsibilities and challenges related to the safety of the intersections on their roadway system. By beginning any traffic safety effort using a data-supported approach, those agencies will be in a better position to address their highway safety needs. While the challenge to decrease the number of intersection crashes on local rural roads can be challenging due to limited resources, there are a number of low-cost proven countermeasures that can be installed to improve intersection safety on local roads and many can be installed within a short timeframe.