Why Do Some Road Signs Have Holes? Here's What They're For

If you've spent some time on highways and rural backroads, you may have noticed something strange – some road signs are peppered with holes. It could be any marker, from a simple red "Stop" to a multicolored highway distance sign. Most people wouldn't think twice of such an oddity. After all, being exposed to the elements, the holes could simply be a sign of neglect or harsh weather. In reality, these are a result of two different things.

Depending on where you are, the hole-riddled sign could be the result of deliberately engineered perforations. These provide greater wind resistance while reducing drag, preventing the post from being blown over in regions with notoriously strong winds. Others, however, are bullet holes created by roadside vandals using signs for target practice. Whatever happened to soda cans and beer bottles?

Unless you were there when they were made, it's hard to tell how the holes on any given road sign came to be. Understanding the difference doesn't only reveal the genius of engineers, but also the hidden costs and safety implications presented by damaged road signs.

According to a 2020 PLOS One study, drilling into road signs significantly helps reduce resistance caused by wind. Based on the findings, computational fluid dynamics simulations proved effective in controlling the load resistance. Depending on where you live, you may have to drive through inclement winter weather, enduring hazards such as strong winds that can take down makeshift structures. Imagine what kind of damage it could do to traffic signs. When ripped from the ground, road placards can become a real threat, potentially lodging in a vehicle's windshield or harming cyclists and pedestrians. As a result, areas with harsh winds may design their road signs with perforations so that air can slip through. 

However, bullet holes launched into signs are a different story. As innocent as the action may seem, it can cost local governments more than $10,000 annually in damages, which is even passed on to taxpayers in some instances. Furthermore, shooting at signs also presents safety concerns to road users as it distorts the message and prevents bounce back light at night, ultimately jeopardizing traffic information. While there are a ton of confusing road signs, the majority of them act as more than helpful guides for drivers; they are critical safety tools.