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Jerry Roche: "What is the best way to address severe crashes on your roadways? Or even prevent them from happening in the first place?
The good news is there isn't just one way. There are three, and they can be used in combination depending on your situation.
The three approaches are site-specific, systematic, and systemic. They all provide a framework for reducing future crashes
by deploying safety treatments.
There are differences in these approaches that may make one approach more effective than the others
based on the type of crash problems or risks you are addressing. Let's break down each one.
The site-specific, or 'hot spot' approach, has been the most common and widely used safety
management approach in our toolbox. This approach is based primarily on historic crash rates, frequency and/or severity.
If a concentration of crashes occurs at a particular location, a 'hot spot',
you might expect crashes to keep happening at that location unless improvements are made.
To reduce crashes, you would likely deploy improvements tailored for that site.
The site-specific approach is valuable for mitigating high-crash locations.
However, it is also reactive, meaning multiple crashes must happen at the same location before improvements are made.
Costs can vary widely depending on the improvements. For example, reconstructing a curve where
you have experienced numerous severe crashes over time, may require right-of-way acquisition.
So the site-specific approach is helpful for addressing individual locations
with multiple severe crashes, but is limited to only those locations.
What about the systematic approach? When you hear systematic, think systemwide.
Countermeasures like pavement markings, SafetyEdge, paved shoulders, or rumble strips are proven
to reduce severe crashes, and some agencies require them to be installed on all roads meeting certain criteria.
For instance, your agency might adopt a policy to install rumble strips on all roadways with a posted speed of 55 mph and 2 ft. paved shoulders.
The decision was made based on the safety performance of rumble strips in preventing
head-on and run-off-the-road crashes. The systematic approach provides for a more
widespread deployment of safety improvements than the hot spot approach and can address
roadways that have had few or no crashes, to date.
While a systematic deployment requires no further analysis to prioritize locations,
the approach requires more funding, since all locations are improved over time.
So, the systematic approach addresses many locations regardless of crash history,
but it does not prioritize based on the risk of crashes.
Speaking of risk, let's talk about the systemic approach.
The systemic approach is proactive and involves deployment of proven, low-cost countermeasures
at locations with higher risk. The systemic approach is NOT based solely on past crashes.
It is based on roadway features, or characteristics, that correlate with certain severe crash types.
Think of it like a health checkup. Your doctor asks questions about your family history and your personal health habits.
Does heart disease run in your family? Do you exercise? She uses this data to identify your risk for certain diseases.
If you mitigate the risk factors, you can prevent or reduce the severity of these diseases.
The same can be done with your roadways.
For example, you may know curves with a radii between 500 and 1000 ft., shoulders that are 2 ft. or less,
and moderate traffic volume, correlate with severe roadway departure crashes on your system.
When crashes do happen, the roadway features are similar, but the locations are scattered.
The most effective way to prevent crashes in this scenario is to prioritize locations associated with this risk
and deploy proven, low-cost safety countermeasures, even if the specific locations have not had a crash.
Identify the risk factors, prioritize, and treat the locations with the highest risk, and reduce the potential for future severe crashes!
All three approaches, site-specific, systematic, and systemic, have value for improving roadway safety.
Use them together for a comprehensive approach to make smarter investments, improve your road system, and save lives in your community.
Contact FHWA today to learn more.
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