Simple change, big benefits

New rules for trailer rear impact guards not only protect motorists, but enhance loading dock safety.

By Lester W. Paul

Contents:
Goal of regulations
RIGs: an evolution
Clear and straightforward
Already working

Sometimes a simple safety rule has benefits far beyond those intended. That is certainly true of new federal regulations covering rear impact guards (RIGs) on over-the-road truck trailers.

While designed mainly for highway traffic safety, the new RIGs also make work safer for forklift drivers on loading docks equipped with vehicle restraint systems. The more uniformly positioned RIGs put virtually 100 percent of new trailers within the "hooking range" of vehicle restraints. The new RIGs are also much stronger, thus far less vulnerable to damage and break-away.

New-style RIGs began phasing in about four years ago and have already proven compatible with all makes and models of restraints. More effective restraints mean more trucks loaded and unloaded safely, more accidents prevented, and more lives saved. This is good news for companies that use vehicle restraints, and a reason for companies still relying on wheel chocks to revisit restraint technology.
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Goal of regulations

The new RIG regulations, published by the National Highway Traffic Safety Administration (NHTSA), are designed to protect motorists from serious injuries in case an automobile runs into the back of a truck. In such accidents, a sound and properly located RIG can help absorb the impact and help stop the car before it slides under the trailer.

At the loading dock, meanwhile, the RIG serves as a point of engagement for vehicle restraints, which hold trailers in place at the dock while forklifts load or unload. This helps prevent serious or fatal accidents that happen when a truck separates from the
dock while a forklift is inside or crossing the dock leveler.

Since their introduction in the early 1980s, vehicle restraints have been highly effective, able to engage the RIGs on 95 to 98 percent of trailers. Now, with RIGs in more uniform locations under NHTSA standards (see Figure 1) dock personnel will deal with fewer "oddball" bars that restraints cannot properly grasp.

The stronger RIGs also make it more difficult for restrained trailers to separate from the dock, even if a truck driver disregards communication signals and attempts to depart. In addition, the new RIGs are less likely to be damaged if the truck backs at low speed into rigid objects like fire hydrants, posts or stairways at the loading dock. Preliminary evaluations show that the new RIGs are five to 10 times less susceptible to damage than previous designs.

Simply stated, the new RIGs mean better vehicle restraint performance and safer docks. All restraint users benefit, no matter what make or model they own.
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RIGs: an evolution

Despite their contribution to dock safety, rear impact guards are, first and foremost, traffic safety devices. The truck underride hazard has been well known for more than 45 years. The first regulation requiring underride protection on trucks and trailers took effect in 1953, officially known as the United States Federal Motor Carrier Safety Regulation 393.86. It was later recodified within the Interstate Commerce Commission, and the rear impact device itself came to be referred as the ICC bar.

Only several years later did RIGs (also called underride guards or ICC bars) become important at the loading dock. In the mid-1970s, government safety officials and dock equipment suppliers recognized the need for a mechanical device to secure trucks to the dock during servicing. Wheel chocks, the OSHA-mandated method of holding trailers, had proven ineffective.

One manufacturer's survey of more than 5,000 trailers identified the RIG as the most practical "handhold" for a restraining device. Vehicle restraints were introduced in 1980, and an estimated 160,000 have been installed on loading docks nationwide, greatly reducing the risk of serious forklift accidents.

From the start, the RIG performed admirably as a gripping point for restraints, which proved to be a dramatic improvement over wheel chocks. Still, the RIG had some deficiencies. Older RIGs were usually made of welded sections of steel I-beam or tubing. They could be located from 12 to 30 inches above the road and as far as 24 inches in from the back of the trailer. RIGs at the extremes of these ranges fell outside the reach of many restraints.

Furthermore, RIG strength was inconsistent. Some bars were subject to damage and deformation that could keep restraints from engaging them. In some cases, bars held by restraints would break loose if a truck driver pulled out forcefully.

In the late 1980s and early 1990s, NHTSA re-examined RIG specifications to ensure that the guards would perform their safety function in light of changing car designs. NHTSA developed new standards, subjected them to a lengthy review process, and formally adopted them.
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Clear and straightforward

The main provisions of the new NHTSA standards (see Figure 2) are simple and clear:

• The RIG must be no more than 22 inches above the road and must be recessed no more than 12 inches from the very rear of the trailer.
  
• The RIG must be at least four inches tall and must extend to within four inches of the trailer's sidewalls.
  
• The RIG must meet new energy absorption requirements designed to give it the ability to decelerate an approaching vehicle in order to minimize the chance of it underriding the trailer in a collision. The RIG must absorb 11,240 to 22,480 pounds of force (depending on location along the horizontal member) without experiencing more than five inches of deflection from its original position. This force is roughly equivalent to a 3,000-pound automobile striking the RIG at 30 miles per hour.

The new standards have universally positive effects on loading docks. The "weak link" in vehicle restraining has been strengthened. Responsibility for compliance with published NHTSA standards rests with the trailer manufacturer.
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Already working

New-style RIGs have already recorded up to four years of service. Because the NHTSA standards underwent years of review, both trailer manufacturers and restraint manufacturers had time to anticipate them. In 1994, the Truck Trailer Manufacturers Association (TTMA) issued to its members a Recommended Practice to build RIGs according to the new rules. Nearly all complied.

As a result, about 1 million truck trailers built in the past four years -- nearly 30 percent of the estimated 3.5 million trailers on the road -- have the new-style RIGs. All evidence to date shows that these RIGs are extremely durable and fully compatible with modern docks and equipment. Companies that have hesitated to install restraints because of concerns about weak RIGs may now reconsider.

New RIG standards do not change the fact that dock designs must account for every detail of the customer's operation. In particular, companies must make provisions to restrain vehicles that have no RIGs -- such as trucks with hydraulic rear lift gates. Docks that service such vehicles can be outfitted with restraint systems that securely engage the rear wheels.

In addition, truck bed height ranges, frequency of traffic and special conditions like sloped approaches dictate how to choose and install dock levelers, seals or shelters, bumpers and vehicle restraints.

It is up to the dock equipment manufacturer and its representative to help the customer design docks that are safe, efficient and fully functional, today and in the future.

Lester W. Paul is new product development manager for the Rite-Hite Products Division of Rite-Hite Corporation, Milwaukee, WI.
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