Guard Rails and Impact Ratings
Many types of guard railing for industrial facilities list impact ratings, but what do these numbers mean?
Guardrails are used to separate people, structures, machinery and valuable assets from heavy forklifts weighing more than 10,000 pounds. The requirements for durability and impact resistance are demanding, yet many don’t understand what types of impacts their systems can endure, and under what circumstances. The issue is compounded by the fact that many manufacturers simply don’t provide impact ratings for their guard rails. Some companies fabricate and install home-made railing, which is likely to never have been rated at all.
What can you do to ensure your guard railing system can protect your employees and property the way it’s supposed to?
What do impact ratings mean? How are they calculated?
Some manufacturers simply don’t publish impact ratings for their guard rail. This may be because they don’t want to commit to a number in print, but more likely it’s because these ratings are difficult to digest and understand. It may be that the manufacturer simply does not know what its rail is capable of withstanding. Some manufacturers use different standards to establish impact ratings, meaning that you simply can’t look at one system that claims it can withstand 12,000 pounds and compare it to another that claims it can withstand 10,000 pounds and assume the former is sturdier guard rail. To know this, you must know what standard was used to establish the rating.
- Are there any federal or other rules or guidelines for guard rails? No: there are no government regulations regarding guard rails, other than fall-protection railing on mezzanines or elevated platforms. Consequently, there is no standard definition of what impact ratings actually represent, and no requirement that guard rails have been tested or engineered to any particular strength. Facilities where pedestrians and forklifts operate in the same space aren’t regulated at all for floor-level applications. No requirements are set for the presence of guard rails or how heavily those rails must be built.
- What’s the industry standard? While there is no industry standard, many guardrail manufacturers state their products are designed to withstand a 10,000 pound collision at 4 miles per hour. The MHI (Material Handling Industry)’s Protective Guarding Group is currently working toward standards, but has not yet reached any conclusions. Various manufacturers test their systems separately. For instance, Steel King releases its full testing methodology for its Steel Guard rail system. The company tested its system by driving an 8,000-pound, sit-down counterbalance forklift with pneumatic tires into an 8′ guard rail. The lift traveled in reverse at 5 miles per hour at initial impact. After the one-second impact, the guardrail had a 6″ dent. There was no damage to the forklift, and no observed damage to the concrete floor; no anchor bolts had been loosened, bent, or pulled out. The result for a two-rail system was a rating of 13,000 pounds. Every manufacturer will test differently, and many will do what Steel King did, and document exactly how their ratings were calculated. Since guard rail is critical safety equipment, it’s important to know how published impact ratings were calculated and tested.
- Is guard rail for industrial facilities the same as highway railing? No; not at all. Facility rails are built to deflect an impact and maintain integrity. Highway rails absorb and disperse impacts. That’s why you see shredded or crumpled rails at accident scenes. When an industrial guard rail is hit, it will sustain damage, but doesn’t crumple by design. It holds its ground as best it can, where roadway rails reduce impact and slow vehicles. They’re designed to protect the car and driver, where industrial rails are designed to protect what’s behind the rail.
- What are the limitations? A fully-loaded forklift carries 8,000 to 10,000 pounds, so an adequate guard rail should be able to deflect it. However, this can be counted on the first time it’s hit. Previous collisions may reduce that rating. If you’re protecting people in a work cell, traffic aisle or other area, it’s crucial to identify and replace damaged/weakened guard railing. I recommend that you replace any damaged railing, even if it is protecting machinery or a facility wall or other areas that don’t typically have people present. Also, look at the way the impact has been transferred to the floor. Seemingly minor impacts can reduce guard rail effectiveness.
- What about speed? It changes the game, and for forklifts it changes the game a lot. Remember, these ratings apply to vehicles at whatever the standard was established at (usually 4 or 5 miles per hour) by the manufacturer and testing engineer. Any faster, and the ratings decline. Forklifts going even one mile per hour faster will hit much harder due to weight and density. OSHA recommends that lifts travel no faster than 5 MPH, which is more than fast enough in most circumstances. Lower speeds help prevent accidents in the first place, but also mean that rails and bollards can do their jobs and stop the lift if they must.
- Does the angle of impact matter? It absolutely does. Most ratings assume a 90-degree impacts. Ratings for a forklift traveling backwards can be different than if the vehicle was moving forward or at an angle.
- What about hardware? You should use only the hardware specified in your manufacturers’ installation guide. Flimsier, shorter bolt anchors into the floor or to attach rails will compromise the rail’s impact rating.
- What about heavier rail systems? They’re useful in critical areas because the ability to survive a hit is only part of it. The ability to take 2,000 pounds more can be the difference between a minor accident and a major incident. Not only can the rails take more damage, they deflect less, and less deflection is what you want. This is because the heavier rails won’t deflect a forklift back as far as a lighter one. If you cut 5″ off the deflection, the lift may not smash into something–or someone–else in the area.
- Should I use an unrated guard rail? Probably not. Unrated rails may be inexpensive imports or “home brew”. If you need guard railing, you need it to be able to actually do the job it was designed to do. Not knowing its rating means you can’t know its limitations. In general, you want at least 11 gauge corrugated steel for the rails, and heavy tubular posts. Not all yellow painted steel rail can really safeguard your people and critical assets. There are areas where rails could be installed that are designed for pedestrian traffic control, and not to contain forklifts, of course.
- Will guardrails always stop forklifts? No. A vehicle weighing enough, at a high enough speed, will probably take down most guard rails, in particular if the driver doesn’t let up. That typically doesn’t happen, but it can. Like many other safety measures, guardrails are limited in their effectiveness. But they do work in many situations, and can save lives and property when properly specified and installed.
Guard rails should be installed in preference to paint strips or striping where people afoot and forklifts work in the same space, or where there is critical machinery, storage equipment, or infrastructure. But to be sure your rails can sustain forklift impacts, understand the rail’s impact ratings and track it any time the rail has been hit. Also understand that published capacity ratings are subject to a number of factors–angle, previous impacts, forklift speed and more. This also goes for standalone bollards or other impact
When properly laid out, guard rails don’t inhibit operational speed, but do significantly enhance safety. Contact Cisco-Eagle or another qualified company for assistance.
More on guard rails and traffic management
- Cisco-Eagle’s steel guard rail layout program
- Guard rail varieties
- How to use guard rails to manage corners and turns
Scott Stone is Cisco-Eagle's Marketing Director with three decades of experience in material handling, warehousing and industrial operations. He writes on automation, warehousing, safety, manufacturing and other areas of concern for industrial operations.