The assessment of noise from railway lines is based on the yearly equivalent continuous sound pressure level (Leq), evaluated separately for day (6-22) and night (22-6). Railway noise consists of single events with pauses inbetween. It is therefore beneficial to calculate the Leq values from sound exposure levels (LE or SEL) that describe the energy of a train passage and taking into account the number of events.
The sound exposure level LE or SEL is determined from the time dependent sound pressure p(t) as shown below. T corresponds to
the integration or event time.
The equivalent continuous sound pressure level Leq is determined from the time dependent sound pressure p(t)
as shown below. T corresponds to the integration time.
If a number of ni events with a sound exposure level LEi or SELi occur in the time period of interest T, the continuous
equivalent sound pressure level Leq is given as:
The measurement took place on Mai 26 2005 near Duebendorf at a distance of 10 m from the railway line.
The microphone was installed 4 m above ground. During a period of 30 minutes, A-weighted short time Leq values
were recorded every second. In parallel the microphone signal was recorded on DAT for future evaluation
in the laboratory (Audio example of a train passage).
Equipment in use:
During the measurement three train passages in direction Duebendorf
For the day and for the night period the equivalent continuous sound pressure level Leq of the ralway noise shall be determined. It is assumed that during the day (6-22) 200 train passages occur, during the night (22-6) 34 passages occur. It is assumed that the passages are equally distributed in both directions.