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Robert Lawson

Comparison between different shapes of concrete barriers

Robert Lawson

Generally all shapes of concrete barriers could satisfy the objectives of safety engineers. Other things to be considered are future overlays and the nature of the traffic. If a vehicle impacts on Jersey barrier, a significant portion of its energy is absorbed in the climbing or lifting action that occurs when the tires roll up the lower sloping face.

The level of damage depends on the speed of the vehicle, and here we present

The Highlights of K rails

Low speed: The barrier redirects the vehicle and there is no contact of sheet metal with the face of the concrete wall.

Medium speed: In this case, there will be damage to the vehicle but the occupants will experience minimum forces.

High speed: If an over speed vehicle impacts on safety shaped walls, there will be significant vehicle damage and the potential of injury to the occupants is from minor to moderate.

The only disadvantage of Jersey barrier is that there is a much greater likelihood that a small car will be rolled by the "safety shape" profile. The F-shape design that is a modified form of K rails was specifically engineered to limit the potential for small cars to roll over upon impact.

Vehicles impacting the single slope barrier or vertical barrier would be less affected by roll-over. But, single slope barrier lacks the ability to absorb the crash energy by lifting the vehicle. Also, sheet metal damage is inevitable and the occupants could get the full force of hit. Vertical barriers react similarly but it has an additional disadvantage. The occupants have a chance of hitting their head with the wall if it is high enough. The crash tests show that the performance of the Constant-Slope Barrier is comparable to that of the K rail.

A major benefit of the constant slope, single slope, or vertical barriers is that multiple overlays can be applied without affecting the shape, and therefore the performance, as long as the total height remains adequate. K rails allow for no more than three inches of overlay.

However, K rails are widely preferred because it was specially designed and engineered to limit the potential roll over. Jersey barriers are also used to divert traffic and protect pedestrians and workers during construction works.

The author has been working as a safety engineer in Federal Highway Administration. He takes special interest on Safety barriers and has written many blogs on this subject. He recommends DCC for purchasing K rails. Visit more details.

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