This report sets out the recommended method for predicting l10 (1 hour) and l10 (18 hour) noise levels due to road traffic at points up to 300 M from the road. It also describes how to allow for the effects of obstructions and roadside barriers. It is based on the department of the environment's publication 'calculation of road traffic noise' which should be consulted for a more detailed exposition than is given here. Prediction is for typically adverse noise conditions ignoring non-permanent site features which might influence received noise levels. The designation l10 denotes the level in db(a) which is exceeded for one-tenth of any specified hour. The l10 (18-hour) level is used in regulations and in certain planning considerations; it is the arithmetic mean of the 18 separate one-hourly values of l10 covering the period 06.00 to 24.00 hours, on a normal working-day. Predictions are made in a series of steps, each involving the use of a formula which in most cases is also presented graphically. In many situations the use of the charts will give acceptable accuracy, even though the errors in chart reproduction and reading may result in errors in the final prediction of up to 1 db(a). When high accuracy is required the calculation should be based on the definitive formulae given in part 2. Each step in the calculation should be accurate to 0.1 db(a). The overall result should be rounded off to the nearest whole number, 0.5 db(a) being rounded up. /TRRL/

  • Availability:
  • Corporate Authors:

    Illuminating Engineering Society

    York House, 199 Westminster Bridge Road
    London SE1 7UN,   England 

    Her Majesty Stationary Office

    49 High Holborn
    London WC1V 6HB,   England 
  • Publication Date: 1976


  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00142743
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Monograph
  • Files: ITRD, TRIS
  • Created Date: Aug 4 1977 12:00AM