Guard Rail: Steel vs. Flexible Poly
Steel rails are rigid and more economical, while flexible rails reduce replacement costs. Which fits your needs?
Ouch – those collisions have done some damage
In both cases, the guard rail has deformed. That’s good, because both guardrails have done their jobs and protected the people, equipment or facility structures behind them. On the other hand, you can see that the rail systems have been stressed and bent. One system is rigid steel guard rail and the other is flexible poly guard rail. Let’s see how they match up in form, function and lifetime cost.
Form – the construction elements and shape
Rigid Steel Guard Rail
Steel guard rail is the most widely used guard rail type. It has been around for decades, and has been the industry standard — the only choice — until a few years ago. The primary components of steel guard rail are the square tube steel posts (usually 3″x3″ or 4″x4″ and 42″ high for dual rail systems), base plates, and W-profile corrugated steel rails. Strength and impact resistance relies primarily on the thickness of the steel used in construction and the number of rails high the guard rail is. (See Guard Rail Impact Ratings for more information)
Flexible Poly Guard Rail
Polymer based flexible guard rail has gained significant market share in Europe as more “Green” regulations are adopted by various countries, but also here in the United States. The polymer product consists of round tubular elastomeric plastic posts and rails. Steel base plates are used for anchoring the product to the floor surface much like steel guard rail.
Flexible guard rail systems install similarly to steel except that the posts are have a double layer – a steel post is inside the round poly post using a special mounting system that connects the metal and poly post pieces, providing rigid protection. The rails are attached by sliding them onto smaller diameter tension regulating stubs that stick out from the sides of the poly post pieces. This becomes very important in our function section. The posts are capped off for safety.
Function – how each product performs in the field
Rigid Steel Guard Rail
Steel guard rail is durable. It resists slight bumps and dings with ease. With more powerful collisions though, there is potential for a loss of resistance in the metal strength. The steel guard rail still keeps the moving vehicle from crashing through the barrier it provides unless it has been struck too severely for the rail to maintain its integrity.
Watch the video embedded here: you see that the steel finally does deform with a heavier, faster moving impact. The steel does not return to its original shape and will have to be replaced. The posts will need to be inspected for bending as well and possible replaced.
The critical aspect to understand is damage to the anchor points and floor surface. Since steel guard rail absorbs the full impact and transfers it to the floor, there is tremendous stress at the anchor holes. Over time, the concrete, wood or other surface material with be damaged until at some point it gives way and the guard rail is breached with the next impact. Site audits at facilities have shown some anchor points so damaged that you could wiggle the post back and forth freely. Conditions such as these are dangerous accidents waiting to happen. Whenever there is a collision significant enough to replace rails or posts, the anchor points need to be carefully checked for damage as well.
Flexible Poly Guard Rail
Poly guard rail is durable in several ways. It doesn’t readily show scratches and dings since the color goes all the way through the poly pieces. The elastomeric polymer is also very forgiving in collisions.
Small impacts just bounce back immediately into the original shape. Because of that elastic quality, it flexes on heavier impacts, absorbing and deflecting all the energy of the collision instead of transferring it to the anchor points.
Watch the video embedded here to see how the poly guard rail reacts to impacts. Even with large mass and high speed, there is very little lasting deformation (most flexible rail returns to original shape over a short period of time).
That’s why the rails are slipped over the post stubs instead of being bolted or secured firmly to the post. The guard rail flexes as far as it needs to in order to dissipate the impact energy, then returns to its original shape. Seldom does a rail or post need to be replaced. Additionally, the anchor points at the base plates are nearly unaffected, meaning your guard rail has a longer service life overall.
Cost and return on investment – getting to a decision point
Steel Guard Rail
Steel guard rail is available in a wide range of prices based on the quality and thickness of the steel it is constructed from. It’s important to keep in mind the load weight, forklift speed, and density of traffic for any run of guard rail you plan to install. The faster, heavier and more crowded the traffic, the higher the risk of hitting and damaging guard rail. Heavy traffic patterns such as these require heavy-duty guard rail, such as Steel King’s Steel Guard system. For lightweight loads or speeds, a less robust guard rail or hand rail should be fine. There are no regulated impact standards in the guard rail industry, but we can assist you in specifying the right railing system for your application.
You’ll probably have to replace sections of guard rail from time to time due to collisions. You may even find yourself in the situation where you have to re-install an entire run of guard rail and repair your floors because the floor anchor points have weakened.
However, given the cost difference, steel systems can be replaced more inexpensively than poly systems.
Flexible Poly Guard Rail
Flexible polymer guard rail is significantly more expensive than steel guard rail. It averages between 1.5 – 2 times the cost.
The return on investment accrues over time as you incur fewer damaged sections of rail and less money spent on replacement parts and floor repairs. If you already have steel guard rail, you should have a good idea of what kind of expenditure you’re putting out year over year in repairs (may be a little, may be a lot). You may be able to reduce that figure with flexible systems. The guard rail is yellow throughout, so it never requires paint.
Generally speaking, the higher the load weights, faster the speeds, the more replacement or repair costs you see, the case for flexible systems becomes stronger.
So, the bottom line: which is best for you?
It boils down to your needs and your situation. Steel Guard and Flexible Poly systems are both excellent – and appropriate – for the right applications.
While steel railing doesn’t absorb as much impact, it is less costly. Flexible poly rails cost more, but don’t transmit nearly as much force to the forklift, the rail, the posts, and the floor. If you aren’t sure, call us. Our expert engineers and sales people can help you with planning layouts and provide you with specs and cost comparisons to help you make a decision. We’ll answer your questions, offer suggestions and help you specify and install the right solution for your needs.
More guardrail resources:
- Cisco-Eagle: guard rail systems home page
- Steel Guard rail estimator/configuration tool
- Guard rails and impact ratings
- Video library: barriers and rails
Scott Stone Cisco-Eagle's Director of Marketing. He has over 25 years of experience in the industry.