COMBATING COMMERCIAL VEHICLE NOISE

THE CONCEPTS OF NOISE LEVELS AND DECIBEL RATINGS ARE EXPLAINED AND DEVELOPMENTS TOWARDS QUIETER HEAVY VEHICLES ARE ILLUSTRATED. IN THE MEASUREMENT OF NOISE, THERE IS NEED FOR AGREEMENT UPON A METHOD THAT SPECIFIES THE PROPERTIES OF THE PLACE OF MEASUREMENT, HOW THE VEHICLE IS DRIVEN, THE SPEED, DISTANCE TO THE MICROPHONE, AND THE QUALITY OF THE INSTRUMENT ETC. THE EUROPEAN METHOD SPECIFIED IN ISO RECOMMENDATION NO. 362 IS DESCRIBED. IN EUROPE THE NOISE LIMIT FOR HEAVY COMMERCIAL VEHICLES IS SET AT 89 DB (A) WHEN THE ENGINE POWER IS BELOW 200 BHP AND 92 DB (A) WHEN IT IS ABOVE 200 BHP. FOR THE HEAVIEST VEHICLE THE UK HAS PROPOSED A FIRST REDUCTION FROM 92 TO 89 DB (A) AND AT A LATER STAGE ANOTHER STEP IS PLANNED TO 86 DB (A). THE PRESENT PERMISSIBLE NOISE LEVEL IN CALIFORNIA AND CHICAGO IS 94 DB (A) BUT THE END TARGET FOR 1980 IS 76 DB (A). THE NOISE EMITTED BY A TRUCK IS DEPENDENT ON ENGINE SPEED. THE NOISE EMMISION FROM A LOW-POWERED TRUCK WORKING AT MAXIMUM SPEED IS GREATER THAN THAT FROM AN OVERPOWERED TRUCK DRIVING AT A HIGHER GEAR. THE TREND TOWARDS HEAVIER TRUCKS AND VEHICLE COMBINATIONS IS A SATISFACTORY DEVELOPMENT. OTHER DEVELOPMENTS WHICH HELP REDUCE THE NOISE LEVEL ARE: SPECIALLY DESIGNED EXHAUST SILENCER AND AIR INTAKES; A COMBUSTION PROCESS WHICH RESTRICTS THE SOUND EMISSION BUT LEAVES PERFORMANCE UNIMPAIRED; AND TURBOCHARGED ENGINES. THERMOSTATICALLY CONTROLLED FAN DRIVE WOULD REDUCE FAN NOISE AT HIGH ENGINE SPEEDS. THE NOISE RADIATED FROM THE SURFACES OF THE ENGINE MAY BE DECREASED BY SHIELDING. ACCEPTABLE COMPROMISE IS NEEDED BETWEEN THE DEMANDS FOR COOLING, ACCESSIBILITY FOR SERVICE, PRODUCTION, AND ADEQUATE NOISE SUPPRESSION. PROBLEMS ASSOCIATED WITH REDUCING THE NOISE LEVELS, INCLUDING THOSE INVOLVING LAYOUT CHANGES ARE DETAILED. THE QUESTION OF COSTS IS DISCUSSED. IT IS OBSERVED THAT STRINGENT NOISE LEGISLATION WILL RESULT IN HIGHER TRANSPORT COSTS WHICH WILL HAVE TO BE WEIGHED AGAINST COSTS OF IMPROVED URBAN PLANNING, SPEED LIMITS, AND SIMILAR MEASURES.

• Corporate Authors:

  Noise Control & Vibration Reduction /UK

  ,    
• Authors:
  • Gardell, L
• Publication Date: 1973-2

Media Info

• Features: Figures; Photos;
• Pagination: p. 17-21
• Serial:
  • Volume: 4
  • Issue Number: 1

Subject/Index Terms

• TRT Terms: Combustion; Engines; Fans; Laws; Layout; Measurement; Mufflers; Noise; Noise control; Sound absorption; Speed; Suppressors; Trucks; Turbines; Vibration control
• Old TRIS Terms: Vibration suppressors
• Subject Areas: Environment; Highways; Law; Motor Carriers; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00224236
• Record Type: Publication
• Files: TRIS
• Created Date: Nov 14 1973 12:00AM