When it comes to bollards, size matters, and not just in terms of stopping power. Bollards and barriers should be tall enough to be effective and visible, but not so tall that they are a detriment to your property's aesthetics. Finding that middle ground is critical to keeping your property safe and your bollards relatively undamaged.
Bollards and barriers don't necessarily need much height to be effective—in fact, posts that are less than 12 inches tall can still boast impressive stopping power. While a bollard at or under this short height can stop a vehicle by connecting with its bumper or dragging along its undercarriage, it fails to provide the other various benefits of a taller counterpart. Bollards should provide not only reliable stopping power, but an unmistakable visual deterrent, as well. If a driver does not see a your bollards and barriers because they are too short, he may inadvertently attempt to drive over them, potentially harming himself, his vehicle and nearby pedestrians. While bollards are typically designed to withstand collisions, repeated accidents like this can ultimately compromise your post's longevity. Bollards and barriers should be several feet tall, so that they are easy to spot and easy to avoid.
Not Too Short, Not Too Tall
Of course, you can just as easily install bollards that are too tall. The biggest risk with a too-tall barrier is aesthetic, as they can become an eyesore when they're too conspicuous. OSHA dictates that certain bollards and barriers be painted a distinct yellow hue, which makes them highly visible—on a post that is unnecessarily tall, that yellow is particularly eye-catching. The key is to choose a bollard that is tall enough to be visible without being so tall that it detracts from the setting in which it's installed. Ultimately, that depends on your landscape and your security needs, though a manufacturer and distributor may be able to advise you on unofficial industry standards