Attempts to Suppress


Through out history there have been many attempts to suppress the sounds of function in an industrialised world. Counter measure for highway (including porous road surface/ barriers) aircraft noise, and general reduction of Laeq. levels from the factory down to the individual household have been considered and practiced.

 
 
To the right: Cross section of a vibration absorption device to be found at the end of most lines carrying current for trams. This model from Amsterdam shows two large rubber stompers in a socket between chrome tension bulbs, the idea being to absorb vibration caused by the friction of the tram taking current from the lines.
In the assessment of noise levels, specialists profile spaces taking into consideration the ambient in and outdoor levels of present sound. The effect of a tramline being attached to a building as opposed to an autonomous pole is a principle similar to that of a tin can and string, relaying information by treating the wall as a membrane of sorts. The stomper effectively reduces this relay. In extension of the same principle, it is now common practice to set the track in a rubber 'boot' to reduce noise, vibration as well as wear on the track
 
     
     
 

Industrial Noise Control
Fundamentals and Applications: Second Edition, Revised and Expanded
Lewis H. Bell/ Douglas H. Bell 1993

 

 

 


Provides numerous case studies and end-of-chapter problems for illustration and implementation of noise control applications, as well as solutions to common dilemmas encountered in noise reduction processes.
Industrial Noise Control offers methods to
* predict the noise generation level of common systems such as fans, motors, and compressors
* select the most appropriate equipment to monitor sound properties
* assess the severity of environmental noise
* modify the sources, transmission paths, and receivers of sound
* estimate sound pressure levels
* design mufflers, silencers, barriers, and enclosures
* isolate machine vibration

 
 

Wooden Streets

Natural waterways became first streets of St. Petersburg. Making roads in local conditions was difficult and costly, therefore the initial paving of streets was a duty of city folk. Decree of 1718 stated; ‘each inhabitant should fill sand in front of his yard, and pave the road with stones smoothly...’ The police supervised the correctness of road making. The main type of street surface had been wooden planking of transversely laid planks, later cobblestone pavement appeared. Special attention was paid to water removal: for removal of rainfall waters the streets had transverse inclination from sides to middle portion, collected water was lead to canals and rivers. Due to low surface quality, they had to be renovated every 3-5 years, the level of the streets therefore rose continuously.

       
   
 
       

By the end of 18th century, main streets of the city, such as Nevsky Prospect, had streets made of stone slabs. Outskirts, however, were buried in dirt. In 1794 the streets were lit with 3400 oil lamps, although contractors were stingy with oil and the lighting therefore poor. In 1754 St. Petersburg had 2 thousand cabs, all of which paid 2-rubles duty and were registered with the police. By the end of 1790-s the number of cabs exceeded 4600. This had caused considerable noise as a result of the steel-lined carriage wheels moving over stone, not helped by the refraction of sound as buildings in the main streets became higher and more prolific.

Cobblestone streets were noisy and bumpy, though long-lived. At times wooden or stone floorings were laid upon such streets for the passing of carriages, however this method was not effective. In 1832, inventor Guryev suggested making surfaces of wooden hexagonal pitchers. Comparing to cobblestones, such pavement was soft and noiseless, but had short service life and light-weight pitchers floated up in the event of flood. The wood would also gather much horse manure which would first freeze, later to create considerable stench when thawing out.

The government approved such wooden surface, however, on main streets of the capital, sidewalks were made of stone slabs and fenced with metal bollards, (not provided for city outskirts). In Vyborg and Petrograd people walked in dirt up to their knees.

       
 

       
       
       

Noise Barriers

FDOT Escambia County Transportation Improvement Projects (Florida)
“Contrary to the original plan, which provided for construction of the walls five years after completion of the construction of the project, these walls will be constructed as part of this project. These sound walls will be decorative. The Florida Department of Transportation has prepared conceptual graphics for the proposed bridge columns and walls, sound walls and traffic barriers. The stylized icon of the native Sea Oat has been incorporated into the designs of these elements as has the Navy's Blue Angel FA-18 aircraft. A consistent use of earth tone colors and textures, reminiscent of the sand and sea, will enhance the proposed designs and will lend a unified and memorable appearance to the I-10/I110 Interchange.”

Florida Department of Transportation
http://www.i10-i110.com/