The University of Tennessee, Knoxville


A Systemic Approach to Safety — Using Risk to Drive Action

by Dr. Airton G. Kohls (Source: FHWA-Office of Safety)

Traditionally, safety improvements on roads are based on making upgrades to specific locations with higher than expected number of crashes. According to the National Highway Traffic Safety Administration (NHTSA) in 2010, rural areas accounted for 54 percent of the fatal crashes as compared to urban areas, which accounted for 45 percent. Crashes on rural and local roads are typically spread over hundreds or thousands of miles and are not as densely clustered as crashes in urban areas. It is often difficult for agencies to isolate high-crash locations for safety improvements on rural and local roads. The systemic approach to safety provides state, regional, and local agencies an alternative method to address these crash types and fulfill a previously unmet need.

Systemic improvements can address rural crashes because the focus is high-risk roadway features not specific locations. As an exercise, examine the fatal crash locations in your state from year to year. What do you see? You will likely see fatal crashes occurring at different locations across the system, rather than isolated high crash locations, especially in rural areas. Now look at fatal crashes by crash type in your state. What do you see? You will likely see that the same type of fatal crashes occur from year to year. While it is not possible to predict where fatal crashes will occur from year to year, it is possible to use the roadway characteristics associated with particular severe crash types to predict the locations that are most likely to experience a fatal crash in the future using the systemic approach to safety. The approach is also beneficial for urban areas particularly in addressing crashes involving pedestrians, bicyclists, and motorcyclists.

The systemic approach is iterative and intended to be flexible and easy to apply to a variety of systems, locations, and crash types. Similar to the site analysis approach and most common safety management processes, the systemic planning approach involves problem identification, countermeasure identification, and project prioritization:

Step 1: Identify Target Crash Types/Risk Factors
Review systemwide data and location characteristics to focus on specific crash types and associated risk factors. A lengthier list of potential risk factors is listed in the next column.
For example:
Crash Type — Roadway departure crashes on rural two-lane highways with various roadway features.
Risk Factors — Average daily traffic volumes, curve density, access density.

Step 2: Screen and Prioritize Candidate Locations
Use the risk factors to screen the network and prioritize candidate locations for safety investments that will reduce the potential for future severe crashes.

Step 3: Select Countermeasures
Evaluate countermeasures to select those that address roadway departures on roads with the identified risk factors.
For example:
Rumble strips, cable median barriers, or advanced curve delineation.

Step 4: Prioritize Projects
Prioritize safety projects for implementation based on the risk-based assessment, available funding, other programmed projects, time to develop projects, and other considerations. Highway safety improvement projects are designed to improve safety by minimizing or eliminating risk to roadway users. Rather than managing risk at certain locations, a systemic approach takes a broader view and looks at risk across an entire roadway system.

For additional information, including examples of systemic approaches in states including Minnesota and Missouri, please visit the FHWA Office of Safety website at


Potential Risk Factors
Roadway and Intersection Features

Traffic Volume Other Features


The University of Tennessee, Knoxville. Big Orange. Big Ideas.

Knoxville, Tennessee 37996 | 865-974-1000
The flagship campus of the University of Tennessee System