Los Angeles is widely considered to be the abode of the freeway . It ’s also see to be the house of the film diligence . Afascinating tale from Nate Berg over at Re - Formchronicles the style that two egress forces which would get along to fix LA ended up making the sound of our ever - noisy roadways ( passably ) more adequate for U.S. residents everywhere .
There are many dissimilar definitions of thruway which we could drop all day debating ( include what to call them : freeway ? highway ? parkway ? ) . But the Arroyo Seco Parkway , which opened in 1940 as a corridor from downtown Los Angeles to Pasadena , was the first in the area to be form - separated — specifically design to move cars at greater speeds . This also leave in louder street from the speedier traffic — something that technologist had n’t really study into consideration when build the freeways , which in the beginning simply slit through exist neighborhood . ( In fact , it ’s the tires that are to blame — which have produce in size of it from two or three inches in the 1920s to over a foot - wide , making for very noisy street today . )
It was another LA pike that open a few day after , the Cahuenga Boulevard Parkway , which slices through the Cahuenga Pass in Hollywood where the 101 travels today , which would transform the kinship that these main road had to the communities around them . After the Cahuenga Boulevard Parkway opened , it was determined almost directly that the freeway audio was undermining the performances at the Hollywood Bowl , a bombastic outdoor performance locus adjacent to the fresh roadway . In 1945 , acoustical physicist Dr. Vern O. Knudsen was the first person to recommend a wall especially designed to keep dealings sounds out of the Bowl :
work with the California Department of Public Works to meditate road stochasticity near the Hollywood Bowl , that “ a wall or parapet , built to a height of at least 10 feet above the perambulation walk , be construct along the southeast corner of the Bowl , thus enclosing the entire seating area with a substantial paries which will do as a sound screen against street and Freeway dealings interference . ” Such a paries , Knudsen advise , would reduce noise inside the Bowl by up to 6 decibel , tantamount to the noise drop of sprain off the television in your living way .
While the wall itself was n’t built , Knudsen ’s hypothesis encouraged the film industry , which managed motorway - adjacent exposed - tune studio lots , to shop some of the first prescribed “ sound survey ” to enter out how to keep freeway audio at bay :
The Association of Motion Picture Producers teamed up with the Department of Public Works to study freeway disturbance , and intelligent engine driver from Universal International Studios brought their General Radio speech sound metre and Magnecord mag tape recorders to the sides of these new throughway to take measuring . These early studies continued throughout the ’ 50s and ’ 60s and help to set the measure for acceptable levels of noise near freeways .
The first prescribed speech sound wall was built further Frederick North , in 1968 in the city of Milpitas , but racket barriers presently became widespread throughout California . Although these interference were more to protect commercial-grade concerns at first , the Noise Control Act was eventually enacted in 1972 to keep local residents from being exposed to excessive superhighway noise . As of 2010 , there were 2,748 elongate miles of noise barriers built in the U.S. , fit in to the Federal Highway Administration .
Top ikon : The Hollywood Freeway in 1950 via Re - Form
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