What is unknown history of "soundproof walls on highway" which we usually see casually
If you ride a car well or drive, once you've seen it rises aside the highwaySoundproof wallis. Although it is a soundproof wall built to not leak the noise emitted from cars to the surroundings, it deals with articles on the design of buildings etc. as to what origin was originallyRe: formHas posted articles cooperated by automobile manufacturer BMW.
Muting the Freeway - re: form - Medium
Running on a highway, the soundproof wall will continue to look at most of its journey. It can be said to be an essential building to protect the environment around the road, but sometimes it is sometimes disappointing because you can not see the scenery at large. This situation is of course the same for American highways in the automobile powers as well, especially in routes running in urban areas, soundproof walls are being built in many cases. It is a soundproof wall that tends to overlook because it sees it too frequently, but if you look closely you will surely know that it is designed and made by someone's hands.
What is different from general designs is that the soundproof walls are basically "not made too conspicuous". It is dare not to obstruct the driving force of the driving car, but it is made inconspicuously, but on the other hand, when it becomes too simple design, this time, contrary to giving the driver a monotonous scenery invites drowsiness It also causes harmful effects such as putting away. In this way, the soundproof wall of the expressway is devised to invisible in a place unknown to the user.
◆ History of sound barrier was born
The history of soundproof walls is closely related to the history that the highway (freeway) developed in America. The following picture shows the state of a typical soundproof wall built in the American freeway. I think that there are many people who have seen soundproof walls made of materials such as concrete blocks, iron plates, bricks, TV and movies, and of course, in the US.
Sound Walls on Vimeo
A freeway was born in the United States, and it began in 1940 that it began to develop. There seems to be various opinions as to which "first" freeway is, but in general it is said that "Arroyo Seco Parkway" connecting Los Angeles, California and Pasadena was the first time a modern freeway was laid It is thought. Site summarizing the history of freeways in California "California HighwaysAccording to Daniel Feigen, who operates a business in the 1920s, there is already a thing that seems to be a freeway on the east coast opposite to California, although it can be said that Arroyo Seco Parkway was designed under the influence, He said that the various features had something in common with the modern freeway.
However, such Arroyo Seco · Parkway also said there are significant differences from modern freeways. Mr. Fagen says that the difference is "there are lots of curves, and contemporary people think" not safe "in terms of current standards, once you run, you can understand."
The reason is closely related to the way the car is built in the era when the highway was made. It is in Los AngelesPeterson Automobile MuseumAccording to Mr. Leslie Kendall who is the lead curator at the time, the number of vehicles themselves at that time was smaller and the performance was not so high at the time, so the safety required for the road was lower than the modern day . For the people of the time, the highway is a road to enjoy leisurely while enjoying the scenery and it seems that it was not intended to go to the destination as soon as possible like the present age.
However, when World War II ends and American society starts full-scale growth, how to perceive cars will change completely. As the performance of the car improved, the speed continued to increase, the engine grew larger, the car body became lower, and the width of the tire became wider to satisfy the required vehicle performance.
And Kendall says that the biggest factor of the noise emitted by the car is the road noise emitted from the tire. Although engine noise and wind noise of the car body decreased due to technological progress, it is a very difficult task to erase the noise generated from the tire that only touches the ground and supports the driving in the automobile. When the ground contact surface of a tire made of soft rubber comes into contact with the ground, the soft material bites into the unevenness of the ground, causing grip of the tire. The next time the tire rotates and the tire is peeled off the ground, it is the biggest cause of the noise emitted from the tire.
According to Mr. Kendall, the width of the tire in the 1930s was at most about 5 cm, whereas the tires of about 10 cm in the 1940's and 15 cm in the 1950's were also becoming common . Due to the widespread use of such wide tires and the spread of automobiles themselves due to motorization, the number of vehicles running on the highway has increased and eventually the noise is caught as a problem.
The birth of sound barrier
The problem became remarkable when entering the 1940 age group, and it became a big problem especially in California where the entertainment industry developed. The famous outdoor music building built in 1920Hollywood BowlThen, it extends from Arroyo Seco · Parkway mentioned aboveCahuenga · Boulevard · ParkwayFrequently occurred the problem that the noise emitted by the performers seriously disturbs the performers and audiences.
This issue was addressed by Dr. Bern O. Knudsen, an acoustic psychologist at UCLA (University of California Los Angeles). In a study report conducted in 1945 with the help of the California authorities, "From the road or traffic that has a height of at least 10 feet (3 meters) from the ground to the southwestern side of Hollywood Bowl It is advised to provide a barrier to function as a "sound screen" that blocks noise. According to doctoral research, this measure will reduce noise of up to 6 dB (decibel). This will result in the same muffling effect as when turning off the TV on the living room.
In addition, at the time in California, the highway was constructed here and there, so the Hollywood movie industry named in the world will be greatly affected. Noises that had never been before arrived within the studio, and it came to appear as a big problem at the scene of movie production. To cope with this problem, organizations and companies such as the Hollywood Film Producer Association and Universal Music Studio collaborated to advance approaches to establish acceptable noise levels.
And, of course, there is no doubt that it is the inhabitants living in the vicinity that are greatly affected by these noises. In California where the highway frequently goes near the private house, the occurrence of the noise damage to the residents is also regarded as a big problem, and gradually the importance of the noise control has become increasing among people.
It was also the introduction of soundproof walls that was used to counter that. Mr. Aaron Betitt, a specialist in noise control and mitigation, says, "It is a very simple thing about the mechanism of the sound barrier, the basic idea is to" prevent sound energy from being transmitted from the source to the receiver " In this case, the source is the car and the recipient is the residential of the public in most cases When you place an object with a large mass between the two, some of the energy is obstructed by it, I will be led to you. "
Based on these ideas, in 1968 the first public soundproof wall in the United States was born in California. Soundproof wall built to block between Interstate Route 680 with 8 lanes and neighboring houses remains as it is now, as follows.
Later, in 1969 it is obliged to implement environmental assessment including noise during public developmentNational Environment Policy Act, And in 1972 aimed at "providing an environment free from noise that threatens health and welfare to the whole American citizens"1972 Noise Control ActHas been enacted. In the following two links, you can compare by listening to the difference in noise that can be heard inside and outside the soundproof wall.
Medium / highway side of soundproof wall
Outside the soundproof wall · Residential side
In this way, the soundproof walls that brought back in the 1960s have continued to expand to the whole nation afterwards. As of 2010, 2758 miles (about 4,400 km) of soundproof walls are being built by government budgets.
◆ Design of soundproof wall
In this way, although it is a soundproof wall that can be said to have melted also in the "American landscape", various efforts are also being made about its design. Mr. Patti Watanabe, who oversees the road design in the highway in Los Angeles and nearby Ventura County, talks about its design, "In many cases we will use concrete blocks." Mr. Watanabe is responsible for visual designs such as plants and buildings on the side of the road, rest areas, and among other things the design of the soundproof wall is included.
Basically, the material of the soundproof wall is a concrete block, and it is said that it is being constructed by combining four kinds of shapes. Beige, brown, tan, light tan, red, gray, etc. are available in colors. The basic design style is to combine blocks of two colors as shown in the picture below, and it is said that it should not excessively become conspicuous while not to bore the driver by moderately giving a visual change, High level design that can be said unexpectedly is demanded.
Also, Mr. Watanabe explains why he does not make so many changes, "We can reduce costs by reducing types, we must be good users of public budget." Mr. Watanabe says that around 1990, various efforts were made by incorporating design into such a simple soundproof wall as well. However, in any of those cases, never more gorgeous things have never been adopted. The reason for this is that "I must not disturb the driver" because it is regarded as the most important.
Soundproof walls, which are indispensable for automobile superpowers and the United States, are required not to disturb people's sight but to have a high level of hurdle to show moderate presence. However, due to years of efforts and people's ingenuity, the soundproof wall seems to be "literally" melting "into the American landscape.