Night-time traffic assumptions for road noise impact prediction

摘要

French regulations relating to noise due to new or extensively modified roads have recently been modified [1]. Previously, the sound level of the road was only evaluated by the LAeq (8.00-20.00) indicator, as this was considered as representativeof the nuisance suffered by the residents throughout the day (day, evening and night periods combined). The new texts defined two evaluation periods, one during the day (6.00 to 22.00) and the other at night (22.00 to 6.00), and for each one the LAeqsound levels not to be exceeded in front of residents' buildings.As the difference between the acceptable sound levels during the day and night is 5 dB(A), the threshold relating to the night period is often the most restrictive. In this situation, the night period is taken to design anti-noise protections. In order to reliably predict LAeq (22.00-6.00) caused by a road in the design phase, we had to develop traffic assumptions for this period.