Chapter 17

Excessive Exhaust And Muffler Noise

6-17-1: Legal Authority


Idaho Code section 50-302, and article 12, section 2 of the Idaho Constitution authorize the City to regulate, limit and control motor vehicle noise, smoke or exhaust within its limits. (Ord. 25-17, 7-25-2017)

6-17-2: Purpose


Disturbing, excessive or offensive motor vehicle noise, smoke or exhaust interferes with a person's right to enjoy life and property and is detrimental to public health and safety. The purpose of this chapter is to regulate excessive motor vehicle noise, smoke or exhaust within the limits of the City to promote the public health, comfort and convenience of the City's inhabitants and its visitors. (Ord. 25-17, 7-25-2017)

6-17-3: Scope


This chapter sets forth procedures, policies, standards and requirements applicable to motor vehicle produced excessive noise, smoke or exhaust, including, but not limited to, decibel limits, muffler systems and other noise suppressing systems and devices. (Ord. 25-17, 7-25-2017)

6-17-4: Definitions


For the purposes of this chapter, the following terms, phrases, words and derivations shall have the meaning given herein. When not inconsistent with the context, words used in the present tense include the future tense, words in the plural number include the singular number, and words in the singular number include the plural number. The word "shall" is always mandatory and not merely directory. Words used throughout this chapter, but not defined herein, shall have their plain, ordinary, and common meaning. Words in any gender shall apply to the feminine, masculine and neuter genders.

A-WEIGHTED SOUND LEVEL: The sound level measured in decibels ("dBA") using the A-weighted network which is the network that most closely resembles what the human ear hears.

AMBIENT NOISE LEVEL OR BACKGROUND NOISE: The composite level of existing sound from all sources, excluding the sound being monitored, at a given location and approximate time at which a comparison with the monitored sound is to be made.

DECIBEL OR DB: A unit for measuring the relative loudness or intensity of sounds.

EXCESSIVE FUMES, SMOKE OR EXHAUST: The opaque discharge of fumes or smoke from a motor vehicle's exhaust emissions within the proximity of the exhaust outlet for more than ten (10) consecutive seconds under the following circumstances:

A. As dark or darker in shade than that designated as no. 1 of the Ringelmann chart, for vehicles first sold and registered as a new motor vehicle prior to January 1, 1971; or

B. As dark or darker in shade than that designated as no. 2 of the Ringelmann chart, for vehicles first sold and registered as a new motor vehicle on or after January 1, 1971.

EXCESSIVE NOISE OR UNUSUAL NOISE: Any sound made by a motor vehicle at any time under any condition of grade, speed, acceleration or deceleration, which exceeds ninety two (92) decibels, or any lower decibel level fixed by law or rules adopted by the State of Idaho, as measured on an A-weighted network of a sound level meter from a distance of not less than twenty feet (20') to the side of the motor vehicle.

MOTOR VEHICLE: Every vehicle which is self-propelled, but excludes all vessels which are solely solar or human powered, and electric or motorized personal assistive mobility devices and wheelchairs.

RINGELMANN CHART: The smoke chart with instructions for use as published by the U.S. Bureau of Mines in May 1967 and as thereafter amended, also known as Information Circular 7718.

SOUND LEVEL METER: An instrument which meets or exceeds the requirements of a type 1 or type 2 sound level meter as set forth in ANSI S1.4-1983 or its latest revision. (Ord. 25-17, 7-25-2017)

6-17-5: Measurement Of Sound Level


A. Meter: A sound level measurement made pursuant to this chapter shall be measured with a sound level meter using A-weighting and a "slow" response time, as these terms are used in ANSI S1.1-1994 or its latest revision.


B. Calibration, Adjustment: The sound level meter shall be calibrated and adjusted with an acoustical calibrator of the coupler type to assure meter accuracy within the tolerances in the ANSI specifications for sound level meters, ANSI S1.4-1983 or its latest revision, or an equivalent instrument and its specifications. The sound level meter shall be used as provided in the manufacturer's instructions. (Ord. 25-17, 7-25-2017)

6-17-6: Motor Vehicle Muffler General Requirements And Prohibitions


A. Muffler Required: Every motor vehicle operated within the City limits shall at all times be equipped with a muffler in good working order and in constant operation to prevent excessive noise and smoke.


B. Noise Suppressing System: When any motor vehicle was originally equipped with a noise suppressing system or when any motor vehicle is required by law or regulation of this State or the Federal government to have a noise suppressing system, that system shall be maintained in good working order.


C. Prohibitions: No person or owner shall:

1. Operate or cause or permit to be operated a motor vehicle with a disconnected muffler system.

2. Modify or alter a motor vehicle's muffler system or its operation in any manner, except to conform to the manufacturer's specifications.

3. Operate or cause or permit to be operated a motor vehicle with a muffler cutout, bypass or similar device.

4. Modify the exhaust system of a motor vehicle in a manner which amplifies or increases the noise of the motor vehicle above that emitted by the muffler originally installed on the motor vehicle by the manufacturer.

5. Operate or cause or permit to be operated any motor vehicle which a reasonable person would know or should have known was originally equipped or required by any law or regulation of the State or the Federal government to be equipped with a noise suppressing system while any part of that system is disconnected or while that system or its operation is modified or altered in any manner, except to conform to the manufacturer's specifications.

6. Operate or cause or permit to be operated a motor vehicle which produces such excessive noise as defined within this chapter. (Ord. 25-17, 7-25-2017)

6-17-7: Excessive Fumes, Smoke Or Exhaust


The engine and power mechanism of every motor vehicle shall be equipped and operated to prevent the production and release of excessive fumes, smoke or exhaust. (Ord. 25-17, 7-25-2017)

6-17-8: Exemptions


The prohibitions of this chapter shall not apply to the following:


A. Nonregistered Motor Vehicles On Private Property: Motor vehicles which are not registered with the Idaho Transportation Department because such motor vehicles are solely being driven on private property not open to the public;


B. Exempt Commercial Vehicles: Commercial vehicles which are exempt from emissions testing pursuant to the Ada County Air Quality Board's most current version of their rules and regulations; or


C. Antique, Classic Motor Vehicles: Antique motor vehicles, which have been registered with the Idaho Old Timers license plates pursuant to Idaho Code section 49-406 or with the Idaho Classic plates pursuant to Idaho Code section 49-406A, so long as such motor vehicles are operated and maintained as collectors' items for use in exhibitions, parades, club activities and similar uses, and not used for business or commercial purposes or as customary and usual transportation. (Ord. 25-17, 7-25-2017)

6-17-9: Prima Facie Evidence


A showing that the sound made by a motor vehicle exceeds the maximum allowable decibel level shall be prima facie evidence of the prohibited acts set forth in subsection 6-17-6C of this chapter. (Ord. 25-17, 7-25-2017)

6-17-10: Penalty


Any person found to be in violation of this chapter shall be guilty of an infraction, subject to penalty as provided in section 1-4-2 of this Code, excluding court costs and fees. There is no right to a trial by jury of a citation or complaint for an infraction. Such trials shall be held before the court without a jury. (Ord. 25-17, 7-25-2017; amd. 2019 Code)