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Guardrail Impact Ratings Explained

When specifying a guardrail, we take into account the potential impact it might experience using our Impact Calculator. There are a couple ways in which impact ratings are given by guardrail manufacturers and both can be confusing, so we help by explaining these ratings.


Information you must have:


  1. What is the total weight of your forklifts when loaded?
  2. How fast can your forklifts be driven?


Impact Rating Given in Pounds:


This is the simplest way to rate a guardrail and it seems to be the preferred rating for steel guardrail manufacturers. A 10,000 pound impact rating typically means that the guardrail can withstand (deflect the impact and maintain its integrity) a 10,000 pound forklift traveling at 4 mph. This is helpful in comparing guardrails, but not all that helpful if you want to specify a guardrail for your specific needs, unless of course all your forklifts are limited to 4 mph and weigh exactly 10,000 loaded. 


Impact Rating Given in Joules:


This to us, is the most accurate method of determining what guardrail makes the most sense to use. Joules measure kinetic energy. Here is the formula:


K.E. = (mass * velocity^2)/2

mass = kg

velocity = meters per second


As an example, if we have the same 10,000lb forklift moving at 4mph, we would expect an impact of 8,066 joules.


Here are a few other examples:


15,000 lb forklift moving at 4 mph = 12,144 joules

12,000 lb forklift moving at 5 mph = 13,695 joules

12,000 lb forklift moving at 6 mph = 18,355 joules

10,000 lb forklift moving at 8 mph = 30,859 joules


As you can see speed makes a big difference. 


To help you visualize what the guardrail you might use, here are some examples of the most popular systems we provide to our clients:


HP PLUS: 5,500 joules of impact between uprights

TB400 PLUS:  20,000 joules of impact between uprights

We have polymer guardrail options with impact ratings over 50,000 joules. 


This has of course been simplified and does not take into account your specific circumstances. 


For example: 


  • Angles of impact can change impact ratings.
  • Direct impacts at uprights lower impact ratings over impacts on the rails.
  • Obstructions can keep forklifts from getting to full speed. 


Our team is happy to help take your unique challenges into consideration and come up with a guardrail solution that ensures your workers are safe, but at the same time keeping the system as affordable as possible. 

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