What those ugly concrete walls along the highway are actually for – Jalopnik

Have you ever noticed those 8- to 20-foot-tall concrete walls that stretch almost endlessly along busy stretches of highway? They may seem like barriers designed to prevent your car from passing by unchecked, but that is not their main purpose. Although they are sometimes made of wood or composite materials in addition to concrete, their main function has more to do with protecting nearby residential areas, office buildings and wildlife from harmful noise pollution.

In other words, highway walls are actually sound barriers that deflect or block the sounds of honking, revving, and tire or wheel bearing noises from fast-moving vehicles. And while they may seem like ordinary walls, there is some science behind their bleak existence.

American highways were first introduced to noise buffers in the 1970s, but there is some controversy over their effectiveness in keeping the peace, with some people claiming that they can actually make noise louder in adjacent areas. However, the Federal Highway Administration (FHWA) says field studies have refuted these claims. It adds that noise barriers made from wood, concrete, composite, masonry blocks, exposed aggregates, metal and acrylic or plexiglass panels are all effective at filtering unwanted noise.

For example, the Center says that vehicles traveling at a speed of 100 km per hour are twice as loud as those traveling at a speed of 50 km per hour, and a single truck traveling at a speed of 90 km per hour makes more noise on the highway than 28 cars traveling at a speed of 90 km per hour. That is why highway walls are placed on parts of the highway with high speed and heavy traffic.

It may not seem like it behind the wheel of your trusty junk car, but highways can get as noisy as standing next to a leaf blower, which produces around 70 to 80 decibels at its noisiest times, just before or after rush hour. According to the FHWA, noise barriers can reduce noise levels by 5 to 10 decibels, which is enough to make a tractor-trailer sound like a smaller vehicle from the other side of the wall.

Fortunately, Americans and the rest of the civilized world are not like the French, who resorted to building cement walls to protest the construction of new highways instead of making the place quieter.

Although the walls are not designed to serve as guardrails, they can prevent debris from flying over in the event of a collision. And on the other hand, those walls block visual pollution while allowing homeowners to have a quieter living space, all while helping maintain the value of their property.

Of course, you should keep your eyes on the road, even if you encounter visually interesting highway walls with murals, beautiful textured patterns or plants. What is clear is that they are here to stay, and we will see more of them as the urban landscape expands.