Balance between safety and performance

In the US and Canada, all highway trucks with a Gross Vehicle Weight Rating (GVWR) of 10,000 lbs. (4,536kg) or more are required by law to have a rear impact guard (RIG). This safety component extends below the rear bumper and serves the purpose of stopping lighter and smaller vehicles that impact the rear from under riding the truck.

Recently, Wabash National has spent considerable time, money and R&D resources specifically focused on enhancing RIG performance in terms of passenger vehicle safety as well as trailer performance.

“Three years ago, we began development of a new RIG solution to reduce passenger compartment intrusion (PCI) in offset collisions. We could not add significant weight or costs, nor make the trailer impractical in any way,” explains Andrzej Wylezinski, Manager of Structural Engineering at Wabash National.

Higher design standard

The goal was to develop a RIG that would prevent PCI in a 35 mph 30 percent overlap crash scenario. A 30 percent overlap refers to the amount that a passenger car is interfacing with the width of the trailer.

Traditional RIG components utilize 2 vertical members that extend down from the bumper to carry the horizontal bumper tube. The idea with the new design was to use four vertical posts and a longer, reinforced bumper tube to absorb energy better and deflect rear impact at any point along the bumper.

“With traditional materials, the new design would have added a significant amount of weight, so we looked to advanced high-strength steel,” explains Brian Belcher, Structural Engineer, Wabash National.

High-strength steel delivers

In the end, the RIG-16 utilized sheets of Strenx 110XF steel in 3mm and 2mm thicknesses.

“As we learned how to process the advanced high-strength steel, we discovered its greatest attributes as well as the uniform, fine grain structure that gave superior toughness in impact,” says Wylezinski. “The steel is also friendly in cold forming and welding.”

Numerous benefits

The RIG-16 Rear Underride Guard System was released on the market in early 2016. During its first year of production, thousands were sold and put on the road.

“We really think that the characteristics and properties of the material were perfect for the application and this is part of the reason we are proud of what we have accomplished. The weight, formability and weldability played greatly into the development process. We would not have been able to develop the RIG-16 without high-strength steel,” says Wylezinski.

Swedish Steel Prize Jury motivation:

Wabash´s new rear impact guard for trucks and semi-trailers exceeds North American standards also for demanding off-set impact. The optimized design utilizing high-strength structural steel has been verified with extensive full-scale testing that reveals superior performance in protecting the people in the colliding car. The patented system gives excellent energy absorption, minimum damage of the heavy vehicle, as well as very cost effective manufacturing and assembly.