Monday, February 16, 2026

Safety Message: Brake System Blockages

While issues with brake system continuity are statistically rare, ONRSR is aware of at least two incidents in recent years in which the compromised operation of air brake systems resulted in safety occurrences with potentially serious consequences.

In one incident, what began as degraded brake performance associated with an internally delaminated brake pipe hose, escalated to a much more serious situation when the train consist separated mid-journey. While experiencing brake performance issues, the crew was unaware the train had separated (due to the partial blockage in the brake pipe hose caused by delamination) and proceeded with the first part of the train for 20 kilometres before realising the separation had occurred.

Failure to open headstock cocks when coupling rolling stock is the most common cause of trains departing with ineffective brakes and is usually identified and managed through train examinations and continuity testing procedures.

However, there are other less common causes of these incidents that have occurred on Australian railways that operators should be aware of and manage through appropriate controls.  These occurrences can result in partial blockages and therefore continuity testing may not be an effective control for detecting the following faults.

• Blockage due to insects building nests inside brake hoses. 
  Operators should ensure that dummy couplings are used when rolling stock is not coupled together. Operators must pay close attention to rolling stock that has been stored outside for extended periods of time.
  

• Blockage due to internal delamination of brake hoses. 
  Operators should ensure that hose condition is inspected at scheduled maintenance intervals and should schedule replacement of hoses based on manufacturers recommendations and environmental service conditions.
  

• Fitment of incorrect length brake pipe hoses.
  This can cause kinking and partial blockages of hoses, especially when a train travels through a curve. These issues may not be detected during a train examination performed on straight track. Operators should ensure that the correct length of hose is documented for each class of rolling stock on maintenance check sheets and work instructions.
  

ONRSR is aware that there are many locomotives in use around Australia of similar (and older) age to those involved in the occurrences it has recorded and reviewed. Although rare occurrences, the potential for serious consequences is high. As such ONRSR encourages operators to familiarise their operational and maintenance staff with this Safety Message and ensure flexible air hoses are scheduled for routine replacement as part of maintenance regimes.

For further information or to ask any questions, contact your local ONRSR office.