Rolling stock runaways and the importance of rolling stock braking systems
13 August 2019
When a rolling stock braking system is ineffective at controlling speed or holding rolling stock stationary, there is the potential for a runaway resulting in a derailment. Incidents in Australia and overseas have brought into sharp focus the importance of such braking systems.
Most rolling stock is fitted with two (2) types of braking systems: an automatic, continuous air brake and a manually applied hand or a spring-applied parking brake. The automatic air brake is used to control train speed while the hand brakes and/or spring-applied parking brakes are used to hold rolling stock stationary when not in transit.
The automatic air brake system cannot be relied upon to hold rolling stock stationary in excess of limits prescribed in the Rail Transport Operator (RTO) brake instructions. If the locomotive independent brake cannot hold the train on the gradient, hand brakes should be applied to trailing vehicles to supplement the independent brake. Brake instructions should state how many handbrakes should be applied to supplement the independent brake for particular train loads on particular gradients.
There are some key controls to prevent rolling stock runaways.
- A train should not be held on a grade using only its automatic air brake for more than the time indicated by the brake instructions of the RTO. If a train parks for a significant time, stalls or is parted on a running line, the crew must apply a sufficient number of vehicle hand brakes to supplement the locomotive independent brake, as defined by RTO’s brake instructions, to hold the train stationary on the grade.
- Overloading a wagon or passenger carriage will marginally reduce the effectiveness of the braking system.
- There should be clearly defined go/no-go limits for the minimum number of functioning brakes on a given consist as defined by RTO’s brake instructions. These limits must be strictly observed.
- Air brake system continuity must be maintained throughout the whole length of the train to ensure that all sections of the train will come to a stop if the train is parted.
- Every time rolling stock is coupled together to form a train, testing of the braking system for leakage, functionally and continuity as defined by RTO’s brake instructions must be performed.
In yards and maintenance situations the following issues are also relevant:
- De-railers, baulks, buffer stops or catch points found at the limits of yards are the last line of defence in preventing a runaway.
- When wagons or carriages are uncoupled from locomotives hand brakes must be applied on the wagons or carriages. Spring-operated park brakes will apply automatically.
- If the air brake system needs to be isolated to perform rolling stock maintenance other means of restraint such as chocks should be used to prevent runaway.
Under the Rail Safety (Local Operations) Act 2006 (Vic), RTOs have a duty to ensure safety so far as is reasonably practicable. In meeting this requirement, RTOs are encouraged to take the points above into account in managing the risks of rolling stock runaways. Additionally, it is important Rail Safety Workers are made aware of, and are familiar with, these controls and receive adequate training from the RTO on how these procedures and controls are to be implemented.
Pictured: Rolling stock runaway and derailment, Beaufort 1910