Digital Track Occupancy


Two of the most significant risks associated with work-on-track activities are location assurance and the reliance on verbal communication to transfer critical safety information. Even though procedural failures resulted in many of the recent fatalities in the Australian Rail industry there has been little adoption of modern technology to alleviate these risks. A smartphone application named 4PTW has been created to address these safety concerns. The application replaces voice communication with secure electronic data transfer, provides a map for greater location assurance, and utilises built-in GPS technology to improve work-on-track safety. 4PTW provides these benefits without the need for extensive infrastructure overhauls or fundamental changes to current work-on-track protocol. 4PTW has been commissioned across a number of rail lines across New South Wales (NSW) on networks that range from regional to high availability freight corridors, totally more than 2,500km of operational lines.



There have been a number of rail incidents where the reliance on verbal communication and lack of location assurance have been identified as a primary causal factor. The ‘Rail Safety Report 2014-2015’ stated that “Worksite protection in Australia relies heavily on rules and procedures to protect people undertaking rail safety work. These administrative controls are highly vulnerable to human error, and potential consequence of non-compliance can be fatal.” Work-on-track has been recognised as a priority for the Office of the National Rail Safety Regulator (ONRSR).


The prevention of further work-on-track incidents is dependent on the development of systems to reduce the reliance on human administrative process and controls.

The following areas were identified as improvement opportunities:

• Verbal communications – heavily prone to human error

• Location assurance – misunderstanding of worksite limits leads to potentially unsafe situations

• Agreed arrangements – transparency of information is needed to ensure clarity of understanding

• Competency requirements – ensuring Protection Officers are qualified for tasks they are undertaking

Criteria for success

The solution needed to address the following criteria:

• Avoid the introduction of new devices or infrastructure

• Must improve location assurance

• User interface needs to provide an intuitive dynamic display and be simple to use

• Needs to interface with existing train control systems while maintaining security of the control network

• The app should not change the network rules and procedures

• Provide an alternative to voice communications

The Solution

The solution created by 4Tel is the 4PTW application.  The application was implemented in NSW on the 6 September 2017.  On the first day of operation 49% of TOAs were issued using 4PTW, this increased to over 75% in the following four weeks.  As of August 2020, it is the preferred method for gaining access for work-on-track activities, and has been involved in the issuing of more than 80,000 work on track authorities.

The 4PTW application was designed with the user in mind as it will not drain battery life and has been developed to work on both Android and iOS (Apple) devices.  While the majority of Protection Officers will have smartphones, paper forms and voice communications are still accessible for staff unable to access the PTW application.

4PTW is available on the Play Store and App Store for public download.  This has proven to be an effective mechanism for distributing the application to wide-spread, field-based staff.  The seamless integration with smartphone technology, combined with stakeholder engagement and considered design has contributed to the rapid uptake of the technology.


Using 4PTW

The 4PTW application has four primary screens; Home screen, TOA screen, LOW/WIC screen, and Map screen. A simple colour scheme has been adopted to clearly indicate the current authority status.

The home screen clearly lists all the current and proposed authorities for the current Protection Officer and their name and contact number. It is critical that Protection Officers keep their phone number up to date as SMS services are used frequently. Contact details can be updated within the application which will automatically update the train control system database.

The TOA screen details any TOAs or Route Control Blocking (RCB) authorities. The LOW/WIC screen provides details of Work In Corridor (WIC) or Look Out Working (LOW) authorities. The map screen shows the Protection Officer’s current position and relative worksite limits. The worksite limits can be pressed to confirm details. If the worksite is following a train and the train’s location is available it can also be viewed on the map.

Data Security

Data security concerns were addressed through extensive security enhancements to external access to the train control centre and an application login process. The application login process involves signing in using current rail industry credentials which ensures that Protection Officers are qualified for the work they are planning to undertake.

The simple screen design improves provides increased clarity and highlights the key details of Track Occupancy Authorities (TOA), Look Out Working (LOW) and Work in Corridor (WIC) requests. Unlike a static paper form, the PTW app interface can dynamically update as required. SMS updates are used extensively to notify Protection Officers about changes that effect their TOA, informing them of when they need to refresh the application.

The TOA Process

The TOA process using PTW:

• Protection Officer will contact the Network Control Officer (NCO) to discuss the details of the protection required

• NCO will create the authority in the train control system and queue the TOA, this sends an SMS to the Protection Officer

• Protection Officer refreshes PTW, reviews proposed TOA, and accepts

• TOA acceptance is sent to the control centre and updated on train control systems

• 4PTW application is updated to show that TOA is current

• Work-on-track activities can now commence

 The Protection Officer must view the map before they are able to accept the TOA. The inclusion of a map strengthens location assurance as it shows the proposed TOA in relation to the Protection Officer’s current location. The proposed TOA limits can either be viewed as control points or track kilometre values. These features have been specifically designed to overcome location translation errors that have previously been linked to operational failures.


Fulfilling a TOA

To fulfil a TOA the Protection Officer uses the 4PTW application to provide assurance that the track is clear and safe for rail traffic.  Providing the track is clear and there is no time extension request, the fulfilment can be completed without verbal communication. If a voice call is required it can be activated from within the application.


4PTW Development

The PTW application has evolved to include new functionalities since its initial release in 2017:

• 4PTW-1 implemented TOAs

• 4PTW-2 added Look Out Working (LOW) and Work In Corridor (WIC)

• 4PTW-3 introduced Route Control Blocking (RCB), a new authority only available through the PTW app

• 4PTW-V a specialised application for track vehicle journeys which tracks the hi-rail vehicle journey through the TOA and generates out of authority alarms if necessary

The introduction of 4PTW does not change existing fundamental rules or processes. While 4PTW is a development in the technology used to issue and communicate TOAs, the principal remains the same.


The 4PTW application has addressed key factors for work-on-track activities and represents a substantial safety improvement for staff. These factors include; the reduction of verbal communication leading to human error, increased location assurance through map displays, clarity on agreed arrangements through transparency of information, and enforcement of staff competency using login credentials. 4PTW continues to be refined and developed to address additional rail safety risks and has continued to provide rail operators with higher level risk controls than has previously been possible.

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