Thursday, April 17, 2025

Safety Message – Long Term Effective Controls

In previous safety messages, ONRSR has provided information about rail incidents and the many controls available to eliminate or minimise the risk of these incidents occurring. In this safety message, we provide a non-exhaustive list of controls that can reduce the risk of not just one, but many types of rail incidents.

ONRSR research into safety systems both here in Australia and overseas identified four such long term effective controls.

Moving block signalling systems
Platform screen doors
Segregating the railway
Electronically controlled pneumatic brakes.

The following discussion of these four controls considers the following key questions:

What is it? (And how it works)
What incidents does it help mitigate?
Where does it apply?
What are the additional benefits?

1. Moving block signalling systems

1.1 What is it?

Moving block signalling systems are signalling systems that allow safe separation between trains, based on real-time information on train speed, distance and location. This safe separation considers the braking capacity of the train, the slope and geometry of the track, and speed, time, and distance between trains.

Moving block signalling systems enable a train’s speed and authority to be monitored constantly, not just when it passes a signal and / or track-borne equipment. Thus, if at any time during the train’s journey a safety condition is breached, moving block signalling systems control the train’s movement (e.g. slowed or stopped).

1.2 What incidents does it help mitigate?

Because the distance between trains, and each train’s speed and authority, is constantly monitored and enforced, moving block signalling systems mitigate:

Train-to-train collisions – see Safety Message - train to train collisions risks, causes & controls.
Overspeed derailments including overspeed through turnouts and switches – see Safety Message - Track Condition and Derailment Risk.
Collisions with workers and plant or equipment on work sites – see Safety Message - ONRSR Investigation Findings Worksite Protection Incidents
SPADs and runaways – see Safety Message - A1 SPADs’ Limit of authority missed by train crew.

1.3 Where does it apply?

The most common applications would be regular scheduled passenger railways such as metro train operations or airport lines i.e. where the consequences to passengers from train-to-train collisions are highest.

Similarly, the system would benefit railways on which dangerous goods are transported through urbanised areas i.e. where a collision or derailment could lead to a catastrophic incident.

1.4 What are the additional benefits?

Higher capacity and throughput of trains because trains can be spaced as close as their safe braking distance.
Greater throughput of trains due to faster approach speeds because the signalling system, rather than the driver, automatically stops the train at the right location.
Reduced maintenance, wear-and-tear and ongoing costs because there is less lineside equipment to maintain and more consistent operation and handling of rolling stock.
Improved or increased availability, reliability and throughput of train services due to more optimised, consistent and predictable train operation and speed.

2. Platform screen doors

2.1 What is it?

Platform screen doors are built-in screens and doors installed along the length of the platform thus providing a physical barrier along its full length. The doors are synchronised and interlocked with the train doors only opening when a train is stopped at the platform and the train’s doors are aligned with the platform screen doors. The train can only move when both the platform screen doors and train doors are proved closed.

The synchronisation and interlocking of train doors and platform screen doors are done via signalling systems - such as the moving block signalling system discussed above. Platform screen doors can either be full height (floor to ceiling) or half-height.

2.2 What incidents does it help mitigate?

Falls between the platform and train – see Safety Message - Falls between the Platform and Train
Falls, trespass or suicide from the station or platform onto the tracks / pit – see TrackSafe.
Door entrapment – see Safety Message - Passengers caught in rolling stock doors Risks, causes and controls.
Fires in underground stations and platforms – see Safety Message - fires in tunnels and underground stations

2.3 Where does it apply?

Platform screen doors are most relevant for regularly scheduled passenger railways such as metro train operations or frequent regional services. They are ideal for railways running trains with the similar dimensions and/or number of doors.

2.4 What are the additional benefits?

Reduced heating and cooling costs by preventing air escaping from stations into tunnels.
Improved network security from reduced intrusion and vandalism.
Faster train approach speeds and thus more frequent services.

3. Segregating the railway

3.1 What is it?

Grade separation creates clear segregation between the railway and any interfaces with roads (at level crossings), pedestrian crossings, occupational crossings and other access points. Segregations can come in the form of bridges, overpasses, underpasses, tunnels, cuttings, fencing or barriers.

3.2 What incidents does it help mitigate?

Train to passenger road vehicle collisions – see Safety Message - Level Crossings and the Importance of Ongoing Risk Assessment - Part 2.
Train to freight road vehicle collisions – see Safety Message - Short Warning Times (overspeed or procedural breaches and Safety Message - Short warning times (wheel-rail interface issues).
Collisions with people, including Rail Safety Workers, collisions with animals and livestock, and trespassers and suicides.

3.3 Where does it apply?

Segregation of the railway and grade separations are applicable to all railways which intersect with road or pedestrian access areas, or areas where animals and livestock can access the track. They are most applied to frequent passenger or freight services where the likelihood and consequences resulting from a collision are highest.

3.4 What are the additional benefits?

Reduced maintenance and other lifecycle costs e.g. maintaining level crossing infrastructure and replacing systems, structures and components of these crossings which often become obsolete.
Improved operational performance due to optimised train speeds.
Easier transition to a moving block signalling system (see above).
Improved road traffic conditions.
Reduced light and noise pollution.

4. Electronically Controlled Pneumatic brakes

4.1 What is it?

Electronically Controlled Pneumatic brakes (ECP) allow instant brake application across an entire train consist, significantly reducing stopping distances and component wear-and-tear. Where other braking systems require the air / flow pressure to reach each wagon (which on a long consist, can take several minutes) this occurs as soon as the brake application is made under ECP.

ECP relies on an electrical circuit rather than air / flow pressure enabling both graduated application and release of brakes. Examples of ECP systems include Wabtec ECP-4200 and NYAB EP-60.

4.2 What incidents does it help mitigate?

SPADs – see Safety Message - A1 SPADs’ Limit of authority missed by train crew.
Sticking brakes, especially on undulating terrain or steeper gradients – see Safety Message - sticking brakes.
Overspeed derailments – see Safety Message: Track Condition and Derailment Risk.
Train-to-train collisions Safety Message - train to train collisions risks, causes & controls.

4.3 Where does it apply?

Freight railway operations which have long consists.

4.4 What are the additional benefits?

Reduced maintenance costs such as wear and tear on brakes, wheels and couplers.
Reduced workload and stress on drivers having to manage brake applications.
Greater throughput of trains.

5. Key documents and actions

The controls listed in this safety message are not applicable to every operator. If not applicable, document your reasons in your risk register or risk assessment. That way, you can demonstrate compliance with section 100 of the RSNL regarding risk assessment. If the controls listed in this safety message are applicable, ensure you comply with your Management of Change processes and start planning now given some of these controls can take several years to implement.

Guidance material that can assist includes: