Q8 What are the noise levels specified in Sections 23130 and 23130.5 VC and how can they be enforced?

Sections 23130 and 23130.5 VC specify noise standards for vehicles operating on the highway (in-use vehicles), and are intended for use in actual traffic conditions. The limits of Section 23130 apply under all conditions of grade, load, acceleration and deceleration, The lower limits of Section 23130.5 apply only to relatively level roadways and under conditions of relatively constant speed. They specifically do not apply to areas of congested traffic, that require noticeable acceleration or deceleration, or within 200 feet of an official traffic control device or change in grade. Although these sections were intended for use in actual traffic conditions, the complexities of noise testing require the testing be conducted in a relatively large open area free of other vehicles and large sound-reflecting objects. This makes in-use vehicle noise testing in most developed areas impractical, where noise complaints are most likely to occur, The CHP does not currently provide either the Instrumentation or training necessary to conduct vehicle noise testing. Enforcement using Section 27150 or 27151 VC is usually more appropriate and effective.

Q9 What is the exhaust noise test specified in 13 CCR? Can this be used for enforcement?

Sections 1030-1036, 13 CCR, were intended to be used by Licensed Muffler Certification Stations as a means of determining if an exhaust system met the requirements of the Muffler Certification Program (when those programs were operational). They specify testing procedures for motor vehicle exhaust noise alone (as opposed to total vehicle noise). This procedure specifies a limit of 95 dB(A) measured 20 inches from the exhaust pipe outlet with the engine operating in neutral, typically at a speed of 3000-5000 rpm. (For comparison, a modem rotary lawn mower with a 5-horsepower Briggs & Stratton engine typically emits approximately 93 dB(A) at the same distance at full speed under no load.) It applies only to passenger vehicles. It does not apply to motorcycles or to vehicles over 6000 pounds gross weight.

Q10 Can this test be used in enforcement?

Not readily. Although much simpler than the test methods specified in Sections 23130 and 23130.5 VC, this test method still requires some technical expertise and a means to determine both the speed (rpm) of the engine under test (tachometer) and the rpm at which maximum horsepower of the engine is developed (information which may not always be readily available), as well as a sound level meter. It is not intended for roadside noise testing. The CHP does not currently provide either the instrumentation or training necessary to conduct exhaust noise testing.

This test is useful, however, for determining if an aftermarket or performance exhaust system complies with VC requirements. It should be noted that the 95 dB(A) level, because it is intended as a simple "go-no-go" type of test, may permit exhaust noise somewhat higher than those permitted under Sections 27201-27206 VC. An exhaust system that complies with the requirements of Section 1036(d)(1), 13 CCR, is deemed to comply with Sections 27150 and 27151 VC.


Knox Letter | CHP Bulletin| Attachment 1 2 3 4
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