[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR325.59]

[Page 744-745]
 
                        TITLE 49--TRANSPORTATION
 
        CHAPTER III--FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION,
                      DEPARTMENT OF TRANSPORTATION
 
PART 325--COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS--Table of Contents
 
       Subpart E--Measurement of Noise Emissions; Stationary Test
 
Sec. 325.59  Measurement procedure; stationary test.

    In accordance with the rules in this subpart, a measurement shall be 
made of the sound level generated by a stationary motor vehicle as 
follows:
    (a) Park the motor vehicle on the test site as specified in 
Sec. 325.53 of this subpart. If the motor vehicle is a combination 
(articulated) vehicle, park the combination so that the longitudinal 
centerlines of the towing vehicle and the towed vehicle or vehicles are 
in substantial alinement.
    (b) Turn off all auxiliary equipment which is installed on the motor 
vehicle and which is designed to operate under normal conditions only 
when the vehicle is operating at a speed of 5 mph (8 kph) or less. 
Examples of such equipment include cranes, asphalt spreaders, liquid or 
slurry pumps, auxiliary air compressors, welders, and trash compactors.
    (c) If the motor vehicle's engine radiator fan drive is equipped 
with a clutch or similar device that automatically either reduces the 
rotational speed of the fan or completely disengages the fan from its 
power source in response to reduced engine cooling loads, park the 
vehicle before testing with its engine running at high idle or any other 
speed the operator may choose, for sufficient time but not more than 10 
minutes, to permit the engine radiator fan to automatically disengage 
when the vehicle's noise emissions are measured under stationary test.
    (d) With the motor vehicle's transmission in neutral and its clutch 
engaged, rapidly accelerate the vehicle's engine from idle to its 
maximum governed speed with wide open throttle. Return the engine's 
speed to idle.

[[Page 745]]

    (e) Observe the maximum reading on the sound level measurement 
system during the time the procedures specified in paragraph (d) of this 
section are followed. Record that reading, if the reading has not been 
influenced by extraneous noise sources such as motor vehicles operating 
on adjacent roadways.
    (f) Repeat the procedures specified in paragraphs (d) and (e) of 
this section until the first two maximum sound level readings that are 
within 2 dB(A) of each other are recorded. Numerically average those two 
maximum sound level readings. When appropriate, correct the average 
figure in accordance with the rules in subpart F of this part.
    (g) The average figure, corrected as appropriate, contained in 
accordance with paragraph (f) of this section, is the sound level 
generated by the motor vehicle for the purpose of determining whether it 
conforms to the Standard for Operation Under Stationary Test, 40 CFR 
202.21. (Table 1 in Sec. 325.7 lists the range of maximum permissible 
sound level readings for various test conditions.)

[40 FR 42437, Sept. 12, 1975, as amended at 41 FR 10226, Mar. 10, 1976]