EPL 12208 - Sydney Trains Frequently Asked Questions (FAQs)

Environment Protection Licence number 12208.
What is wheel squeal?

Wheel squeal refers to a high-pitched piercing noise that can occur as trains travel on curved track. Wheel squeal is usually louder than other types of train noise.

What is angle of attack?

Angle of attack refers to the axle alignment of train wheels relative to the rail, as illustrated, and is measured in milliradians.

Angle of attack

How does angle of attack relate to wheel squeal?

Industry research into curve noise indicates a correlation between wheel squeal and high angle of attack. Industry research into the correlation continues since high angle of attack does not automatically result in wheel squeal, nor does low angle of attack automatically preclude wheel squeal. Currently we use 30 milliradians to indicate high angle of attack.

Why do we monitor angle of attack?

We monitor angle of attack on curved track at Beecroft in order to identify potential causes of wheel squeal (high angle of attack) rather than just monitor the potential effect (noise).

Why do we publish angle of attack monitoring data?

We monitor angle of attack under the conditions of its environment protection licence 12208 and publish the monitoring data under section 66(6) of the Protection of the Environment Operations Act 1997.

Where do we monitor angle of attack?

The map below shows the location of angle of attack monitoring at Beecroft.

The location of angle of attack monitoring at Beecroft.