Queensland Rail balances the community's need for a safe and efficient transport system with the community's expectations regarding rail noise exposure.
To assist the assessment and management of noise from train operations and fixed facilities like stabling yards, the following Rail Noise Planning Levels are applied:-
- 65 dB(A) assessed as the 24 hour average equivalent continuous sound pressure level (LAeq 24 hours)
- 87 dB(A) assessed as a Single Event Maximum Level
These planning levels are to be assessed 1 metre from the most exposed facade of a Sensitive Place (e.g. a home, hospital, school or place of worship).
They are to be applied when Queensland Rail has made a significant change to infrastructure and/or operations. A significant change is where either the LAeq (24 hour) and Single Event Maximum Level changes by more than 3 dB(A) at noise sensitive places. It is generally acknowledged that a change of less than 3 dB(A) is difficult for most people to detect.
Single Event or Time Averaged Levels?
The rail noise planning levels are described in two ways.
For a given period of time (from t1 to t2) a noise event will have an overall sound energy (Leq),as represented by the hatched area under the curve shown below. The peak maximum level is the loudest sound during the time period.
Note that the diagram shown is not representative of noise from a train.
The sound exposure level (LAE) is equivalent to the total sound energy, but is 'compressed' into comparable time frames, usually one second. This enables different sound events to be compared.
A noise event of the same volume that goes on for longer will have a higher sound exposure level (LAE) than a shorter noise event. Note however that acoustic averaging is a logarithmic function. It means for example, the addition of two one second 60 dB(A) levels does not combine to be 120 dB(A), instead it averages to a sound exposure level of 63 dB(A).
The Laeq (24 hours) represents average energy exposure accounting for all the rail noise events over a 24 hour period.
By itself, it is recognised the LAeq (24 hour) level is an inadequate indicator of the potential for time varying rail noise to disturb people.
The Single Event Maximum Level provides a way to account for the potential disturbance based on peak maximum levels. Typically on rail lines through urban areas, the Single Event Maximum Level is determined from highest 15 peak maximum levels over a 24 hour period.
Predictions and Measurements
There are two ways Queensland Rail assesses noise levels.
Via predictions with accurate computer prediction models across an area containing several properties
Via measurements using calibrated noise logging equipment at individual properties.
The large number of noise sensitive places beside our rail network presents a challenge for noise assessments. This challenge is reaching the best balance between resources to undertake assessments and those needed for delivering measures to reduce rail noise.
Computer predictions allow more efficiency and consistency in assessing noise across a greater geographical area than measuring noise at every noise sensitive place for several days.
Following significant changes in infrastructure and/or operations, the accuracy of the noise model and the effectiveness of noise reduction measures are assessed via noise measurements at representative locations.
Train Horns & Whistle Boards
Horns (including train horns), sirens and bells are used by Queensland Rail to deliver auditory warnings which are vital to ensure the safety of Queensland Rail employees and members of the public.
Whistle boards are strategically located within the rail corridor on the approach to high risk locations such as level and pedestrian crossings, bridges and tunnels. When a train passes a whistle board, the train driver must sound the horn so pedestrians, motorists and track workers know a train is coming.
In order to meet the intended purpose of the horns, these devices must produce sound at a level that can be clearly heard above the general background noise and other potential distractions like personal music players and car radios.
It is not appropriate to apply noise criteria, including the rail noise planning levels, to the auditory warning devices.
Adjacent New Developments
Proposed new developments adjoining the rail network may be subject to noise mitigation conditions.
As the responsibility to satisfy such noise mitigation conditions lies with third parties, Queensland Rail will not prioritise further assessment or mitigation for such new developments.
More information can be found at the Department of Transport and Mains Road website