[Code of Federal Regulations]

[Title 49, Volume 5]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR325.5]



[Page 8-9]

 

                        TITLE 49--TRANSPORTATION

 

                      DEPARTMENT OF TRANSPORTATION

 

PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS

--Table of Contents

 

                      Subpart A_General Provisions

 

Sec. 325.5  Definitions.



    (a) Statutory definitions. All terms defined in the Noise Control 

Act of 1972 (Pub. L. 92-574, 86 Stat. 1234) are used as they are defined 

in that Act.

    (b) Definitions in standards. All terms defined in Sec. 202.10 of 

the Interstate Motor Carrier Noise Emission Standards, 40 CFR 202.10, 

are used as they are defined in that section.

    (c) Additional definitions. (1) Hard test site means any test site 

having the ground surface covered with concrete, asphalt, packed dirt, 

gravel, or similar reflective material for more than \1/2\ the distance 

between the microphone target point and the microphone location point.

    (2) Soft test site means any test site having the ground surface 

covered with grass, other ground cover, or similar absorptive material 

for \1/2\ or more of the distance between the microphone target point 

and the microphone location point.

    (3) Ground cover means any of various low, dense-growing plants, 

such as ivy, myrtle, low weeds, or brush.

    (4) Traffic railing means any longitudinal highway traffic barrier 

system installed along the side or median of a highway. For the purpose 

of this part, a traffic railing must have at least 35 percent of its 

vertical height, from the ground surface to the top of the railing, open 

to free space in order to qualify as an acceptable object within a noise 

measurement test site. Further, for the purposes of this part, posts or 

other discrete supports shall be ignored when ascertaining open free 

space.

    (5) Relatively flat when used to describe a noise measurement site 

means a site which does not contain significant concave curvatures or 

slope reversals that may result in the focusing of



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sound waves toward the microphone location point.