Highway Sound Barriers: Drowning Out the Noise
Highway Sound Barriers
Nearly as long as there have been highways in the United States, there have been sound barriers. These attractive and functional structures protect people from the noise pollution generated by cars, trucks, trains, construction and industrial sources. Sound barrier walls reaching heights up to 20 feet have risen throughout the United States since the first were erected during the 1960s in California.
Today, sound barrier walls are ubiquitous along highways and freeways, and although much thought and money goes into designing them, they almost never get noticed by motorists. And that’s the way designers want it, for the most part.
What is a Noise Barrier?
Noise barriers — also known as sound walls, sound berms, sound barriers or acoustical barriers — are outdoor walls that provide the most effective method for blocking noise from busy roads, highways, railways and industrial sources. They’re designed to reduce the transmission of sound, protecting people against noise pollution that can cause stress, high blood pressure, sleep problems and hearing loss.
Noise barriers stop sound from traveling from a source like a car to a receiver, such as a home. The sheer mass of the barrier stops the sound energy and redirects it. About three-quarters of noise barriers are made of pre-cast concrete or cinder block. While they serve a utilitarian purpose, designers and engineers create them to be attractive enough not to detract from the landscape, but not so attractive that they distract drivers.
The Federal Highway Administration reports that as of 2010, more than 2,700 miles of noise barriers constructed with federal funds protected U.S. highways. The barriers can be found in every state except South Dakota, Rhode Island and Alabama, along with the District of Columbia.
Noise vs. Sound
Objects create sound through motion, which causes ripple-like vibrations or waves in air molecules. Humans hear sound when the vibrations reach our ears. Noise, measured in decibels, is unwanted sound that’s considered to be a type of pollutant and is hazardous to human hearing and overall health. The louder a noise is, the higher the decibels, a standard way of measuring noise.
On a highway or a busy road, noise levels are determined by the volume and speed of traffic, along with the percentage of large vehicles like tractor-trailers.
Why Are Highway Noise Barriers Needed?
Noise levels increase along with burgeoning populations, faster and more-powerful vehicles, and increasing levels of road work and construction. With noise having such a powerful effect on human health, the need also increases for methods of controlling this harmful form of pollution. Anyone whose house sits 10 feet away from cars speeding by at 60 or 70 miles per hour can understand the need for a barrier to reduce noise and increase safety.
How Does a Noise Barrier Work?
Noise barrier walls physically reduce noise by absorbing or reflecting it, or by forcing it to take a roundabout path that causes it to dissipate. Sound is a type of energy whose waves grow stronger as they travel away from their point of origin. Vehicles on a road generate sound waves — mostly from the sticking and peeling off of rubber tires on pavement — that travel in all directions. When the waves arrive at a barrier or obstacle, they either are absorbed or bounce off.
Reflective noise barriers — which cause sound waves to bounce off in a different direction — are one of the most effective methods for blocking noise. Reflective walls are made of solid concrete that creates a barrier and pushes sound away from homes or other areas being shielded.
History of Noise Barrier Regulations on U.S. Roadways
The first noise barrier wall was constructed in the United States a half-century ago, when freeways themselves were new. At that time, people drove more slowly and enjoyed the view. After World War II, In the 1960s and later, driving on freeways came to be more about getting somewhere quickly. Speeds increased, and tires became wider, generating the bulk of today’s bothersome highway noise.
The National Environmental Policy Act of 1969 served as the first step at the federal level to address urban growth and its associated freeway noise. Just a few years later, the Noise Control Act of 1972 stated a goal of promoting an environment free from health-jeopardizing noise. It also gave the U.S. Environmental Protection Agency the authority to regulate noise pollution.
Today, agencies including the Federal Highway Administration, the State Highway Administration and the Department of Transportation also set and enforce noise-control policy.
Highway Noise Barriers and Walls – The AFTEC Difference
AFTEC Concrete Fence Forming Systems designs and manufactures precast concrete fencing systems used in road noise barriers and walls. AFTEC products provide the following benefits:
- Acoustic performance: AFTEC’s Highway Sound Wall Panels are vertically cast in attractive textures including split face block, stone and other custom architectural designs, and they deflect noise up to 10 decibels.
- Attractive finished product: Concrete pattern stamping and textured materials add a touch of artistry to freeway infrastructure.
- High level of value: AFTEC panels and columns are cast together as a single piece, reducing production and installation costs. AFTEC’s shorter panels require fewer footings, also saving on labor and materials expenses.
- High durability: AFTEC’s footings use extremely strong, embedded, thick I-beam steel.
- Worldwide availability: Noise walls from AFTEC are available in all 50 states and around the world. To learn more about precast noise barrier systems, contact AFTEC today.
Latest posts by Gale Stott (see all)
- Security Walls for Utilities - September 30, 2015
- Trends and Innovations in Precast Concrete Walls - September 29, 2015
- What Can Precast Concrete Commercial Fences, Gates and Walls Be Used For? - August 24, 2015