If you’ve driven around certain parts of Korea, Europe, or the United States, you may have seen a curious construction along the side of the road, almost as if someone had assembled a whole bunch of plastic lifebuoys into a guardrail. These are a relatively new road safety technology known as “rolling barriers.”
If you’ve driven on the highways and byways of most countries, you’re familiar with traditional steel guardrails. They come in various types and sizes and generally do an acceptable job of capturing errant vehicles that are spearing off the roadway.
Rolling barriers attempt to improve on old-school guard rails by doing things a little bit differently. They aim to reduce barrier penetration and improve safety by use of big plastic rollers. Let’s explore how they work, and look at how they perform in real-world crash tests versus more traditional steel barriers.
Roll On
Roller barriers have been developed by multiple companies around the world. Korean company ETI is one of the most well-known, but they are also manufactured by Shindo Industry and KSI. Each company’s design varies to some degree, but the basic concept is very much the same.
The large plastic barrels of the rolling barrier are installed on posts at even intervals. When hit by a vehicle, the plastic barrels not only deform to absorb the impact, but also spin about the vertical axis, turning some of the impact energy into rotational energy. In turn, rather than the vehicle continuing through the barrier in a straight line, the vehicle is instead deflected to a degree, continuing in a path more aligned with the barrier itself.
This deflection action is one of the key features of the rolling barrier. Indeed, the point of guard rails is often to prevent a vehicle passing through to whatever lies behind—whether that be a sheer wall, a footpath, or a drop off a cliff. The rolling barrier does a good job of redirecting an impacting vehicle back onto the roadway rather than simply absorbing energy as it passes through to whatever lies beyond.
It’s a controversial point in some contexts. If we’re driving along a road, we perhaps wish for an errant vehicle to leave the roadway and remain off it after a crash. However, in many cases, it’s safer for a vehicle to remain on the road after hitting a barrier rather than perhaps spearing off into a ditch or traffic traveling in the opposite direction. The video below is a great example of this behavior, showing a rare comparison between regular guard rails and a rolling barrier under the same conditions.
These rolling barriers have largely remained in obscurity, despite having been marketed by manufacturers for the better part of a decade. The have been installed in various locations around the world, but remain relatively obscure compared to more traditional guard rails. This can largely be put down to their novel nature, and the fact that their additional complexity adds cost versus traditional guard rails, which is a point against them in many contexts.
Their obscurity is not due to any issue of performance. Manufacturers all proudly display their MASH test results at the TL3 or TL4 level, approving them for use on expressways and other dangerous high-speed roads. In the latter case, this requires the rolling barrier to safely deal with a 2425-pound passenger car traveling at 62 mph, a 5004-pound pickup truck traveling at 62 mph, and a 22,046-pound rigid truck traveling at 56 mph.
Watching massive vehicles slam into these barriers at steep angles really shows their capabilities.
As these tests demonstrate, the barriers can handle even off-axis impacts from very heavy vehicles. The rolling barrels often tidily deflect the vehicle, which helps keep it on the roadway. As a bonus, their greater height compared to traditional designs tends to reduce vaulting, penetration, or otherwise flipping the vehicle on its roof or side.
These rolling barriers largely remain a curiosity rather than a mainstream piece of road infrastructure. Regardless, they are a unique solution to the guard rail issue and can be readily installed in many jurisdictions around the world where TL3 or TL4-grade barriers are required.
Now, if you see one of these unique barriers on the road, you’ll know exactly what you’re looking at. You can even gleefully explain their value to your passengers, who will surely appreciate your knowledge. Happy motoring!
Image credits: KSI, Shindo Safety, ETI
Top graphic image: Shindo Safety
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