Road surface sound reduction system

Abstract

A method for reducing tire to road noise generated by vehicles on a road surface comprises generating a pseudorandom unique line pattern, providing said pattern as transverse grooves disposed in the road surface, said grooves being randomized according said line pattern as to one or more of position, frequency, and depth so as to spread the noise spectrum thereby reducing the amplitude or volume of noise generated at any single frequency and are capable of dramatic reductions in noise generated by high speed traffic on roadways. It can be implemented by conventional construction practice at little or no additional cost and eliminates the need for costly structures such as noise barrier fencing in residential areas.

1 . A method for reducing tire to road noise generated by vehicles on a road surface comprising generating a pseudorandom unique line pattern, providing said line pattern as transverse grooves disposed in the road surface, said grooves being randomized according to optimization of said line patterns as to one or more of position, frequency, and depth so as to spread the noise spectrum thereby reducing the amplitude of noise at any single frequency.  
   
   
       2 . A method as claimed in  claim 1  wherein said line pattern is given by a polynomial of the formula:  
       1+x+x 2 +x 3 +x 4 + . . . ,  where x is a coefficient representing 1 unit of time delay and the delay element is optimized for the randomness of said line pattern spacing.    
   
   
       3 . A method as claimed in  claim 1  wherein the line patterns of transverse grooves are imparted by raking during construction of the road surface.  
   
   
       4 . A method as claimed in  claim 1  wherein the line patterns of transverse grooves are imparted by float device during construction.  
   
   
       5 . A method as claimed in  claim 1  wherein the line patterns of transverse grooves are stamped in during construction.  
   
   
       6 . A method as claimed in  claim 1  wherein the line patterns of transverse grooves are cut in the road surface.  
   
   
       7 . A road surface that reduces tire to road noise generated by vehicles traveling over the road comprising a base, the surface of the base having a line pattern of random transverse grooves disposed in the surface and said grooves being optimally randomized as to one or more of position, frequency, and depth so as to spread the noise spectrum thereby reducing the amplitude of noise generated at any single frequency, and said line pattern being generated by a polynomial of the formula:  
       1+x+x 2 +x 3 +x 4 + . . . ,  where x is a coefficient representing 1 unit of time delay.    
   
   
       8 . A method as claimed in  claim 2  wherein said line pattern repetitions length are greater than 250 lines.