Mike Spack, PE, PTOE
I originally posted this article in 2012 when the Federal Highway Safety Administration (FHSA) updated its list of safety countermeasures. In 2017, the FHSA added an additional six countermeasures that are worth mentioning. The FHSA website is a great resource and is packed with a lot research and guidance. Here’s their Top 20 countermeasures based on the latest research:
- Roadside Design Improvements at Curves. Almost 27% of fatal crashes occur at curves in a road. Making simple changes including increasing the clear zone, flattening the slop or widening the shoulders can greatly improve the safety of vehicles navigating a curve.
- Reduced Left-Turn Conflict Intersections – Changes to the geometric design of the road alters how left-turn movements occur. Creating restricted crossing U-turn (RCUT) can reduce injury and fatal crashes by as much as 54%. Check out my article Reduced Conflict Intersections in Action to see an example of a working RCUT.
- Systemic Application of Multiple Low-Cost Countermeasures at Stop-Controlled Intersections – Driver awareness is critical to keeping motorists and pedestrians safe. Implementing multiple countermeasures at a large number of stop controlled intersections can help increase driver awareness of potential conflicts.
- Leading Pedestrian Interval – Giving pedestrians 3 – 7 seconds to enter an intersection before vehicles are given a green indication can reduce pedestrian-vehicle crashes by 60%.
- Local Road Safety Plan – Local roads may be traveled less than state roads, but they often have a higher rate of fatal and serious injury crashes. That’s why it is important to create a local road safety plan (LRSP) to provide the framework to identify, analyze and prioritize road safety improvements. Check the FHWA framework to start your process.
- USLIMITS2 – This free, web-based tool helps practitioners to assess and establish safe, reasonable, and consistent speed limits for segments of roadway. Click to learn more about USLIMITS2.
- Roundabouts – Converting an intersection with stop signs or signals results in about an 80% reduction in injury/fatal crashes and a 45% reduction in overall crashes. The data is very robust – roundabouts save lives because everyone needs to slow down. It’s hard to blow through a roundabout the way a drunk or distracted person can at a signal or stop sign.
- Corridor Access Management – Providing less access points along collectors and arterials (or reducing to three quarter or right-in/right-out accesses) have proven to reduce overall crashes by 5-23% along rural two-lane highways and reduce injury/fatal crashes by 25-31% along urban/suburban arterials. We obviously need to provide access to private property, but that needs to be balanced with the safety and mobility provided along our major roads.
- Signal Head Backplates with Retroreflective Borders – Backplates around traffic signal indications have been used for decades to reduce the sun glare that could wash out the red/yellow/green. Recent studies have shown up to a 15% reduction in crashes with the use of backplates that have reflective tape on them. This improves their visibility, especially when the power is out and the signals are dark.
- Longitudinal Rumble Strips and Stripes on Two-Lane Roads – Cutting in (milling) grooves along the center lines of two lane roads has proven to reduce head on collisions by 44% in rural areas and by 64% in urban areas. Rumble strips along the shoulders of rural two lane roads reduces run-off the road injury/fatal crashes by 36%.
- Enhanced Delineation and Friction for Horizontal Curves – Researchers are finding that a significant amount of crashes in rural areas happen on horizontal curves. Installing more chevron signs along a curve reduces overall crashes by 16% and injury/fatal crashes by about 40%.
- Safety Edge – Safety edge is the practice of shaping the edge of the paved road approximately 30 degrees as it connects into the shoulder. This design eliminates a phenomenon called tire scrubbing that causes the driver to lose control of the vehicle. This treatment is estimated to lead to about a 6% reduction in crashes on rural roads. But since it costs no more to have the road built this way, it has a very large benefit to cost ratio.
- Medians and Pedestrian Crossing Islands in Urban and Suburban Areas – Providing medians on busy arterials that are wide enough for pedestrians to stop in may reduce pedestrian crashes by about 50%.
- Pedestrian Hybrid Beacon – “HAWK” signals may reduce pedestrian crashes at mid-block locations by 69%
- Road Diet – Converting a four lane undivided road to a two lane road with a center, two way left turn lane down the middle reduces overall crashes by about 30%. These conversions often also have the benefit of improving the traffic flow because you get less weaving of traffic around left turning vehicles.
- Walkways – According to the National Highway Traffic Safety Administration, Traffic Safety Facts, there are more than 5,000 pedestrian fatalities, and 70,000 pedestrian injuries occurring in roadway crashes annually. Adding sidewalks can reduce crashes involving pedestrians walking along roadways by 65 – 89%. Well worth the investment!
- Road Safety Audit – Conducting regular road safety audits can identify small changes that can be made before they turn into big problems. I have written a post on 10 Simple Road Safety Audits Everyone Can Do to get you started.
- Yellow Change Intervals – Red-light running is a leading cause of crashes to signalized intersections. The benefits of a well-timed yellow change interval can reduce red light running by 36 – 50%. Make plans to review you signal timing for the year.
- Dedicated Left-and Right-Turn Lanes – Dedicated lanes provide physical separation between turning traffic and through traffic. They are particularly beneficial at two-way stop-controlled intersections. Dedicated left-turn lanes reduce total crashes by 28 – 48%; dedicated right-turn lanes reduce crashes by 14 – 26%.
- Median Barrier – Median barriers help separate opposing traffic on a divided highway and can help redirect vehicles striking either side of the barrier. Cable median barriers are a low-cost solution. Other options include concrete and beam guardrails.
Of the items on this list, my favorites are roundabouts, road edge, and road diets. The incremental cost of implementing these improvements can be negligible if done during road reconstruction. I like big benefit to cost ratios.
Which safety counter measures do you like to use? I am interested in hearing your thoughts. Post a comment below to share your ideas.