Sentric unites Castell, Kirk, Salvo, STI & Zonegreen

Depot Personnel Protection System

Safeguard staff and equipment from the risk of train vehicle movements and electrification with Zonegreen’s Depot Personnel Protection System (DPPSTM) and interlocking solutions.


Protect against unauthorized vehicle movements

Zonegreen’s DPPSTM delivers the highest level of staff safety while maintaining a productive working environment within rail depots. 

Thanks to the flexibility and functionality of the Zonegreen Depot Personnel Protection System, the movement of vehicles in and out of depots can be controlled with increased speed and ease at minimal risk to staff, in a potentially dangerous environment. 


How it works

Trains approaching the depot will halt at the ground level shunt signal which is interlocked with a powered derailer located at around 20 meters from the depot entrance. Access permission is given to the train by a supervisor using a road end control panel (REP). This control panel is positioned at a convenient location within the maintenance building, normally next to the depot doors, giving a clear line of sight to incoming and outgoing trains. 

Only after the derailer has been lowered can the shunt signal show a proceed aspect; audible and visual warnings are activated within the depot on the road on which there is train movement. Once the train is positioned within the depot, the shunt signal is set to stop, the warning klaxons and beacons are turned off, and the derailer is raised to prevent further movement. Zonegreen’s powered derailers are unique in having full Network Rail approval; signaling interfaces and TPWS alternatives to derailers are also available. 

RFID tags with varying authorisation levels – replacing the physical padlock found in traditional DP systems – operate the DPPS™ and identify personnel working in different safety zones. Staff log on to the REP when they begin work, which prevents the derailer being lowered, providing them with physical protection from train movements. 

Key Benefits

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Low risk, proven in use, standard product

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Independently assessed to meet hardware and software requirements of SIL 2

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Independently certified to meet railway and radio EMC standards

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Network Rail PADs approved

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Modular by design to allow easy modification or expansion

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Intelligent distributed control to remove the risk of a single point of failure  

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Multilingual intelligent user interfaces

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Ability to gather real-time operational data

Safeguard critical equipment

Specialist depot equipment can be interlocked with DPPS to ensure that vehicle movements are only permitted when all equipment is in a safe condition. Trapped key or electronic solutions are implemented to monitor the position of third-party equipment and to inhibit its use when a vehicle movement has been initiated on DPPS. 

Mitigate the risk of high voltage electricity 

Trapped key interlocking solutions are employed to ensure that personnel and equipment can only operate in areas that are safely isolated and earthed. 

To provide an additional layer of safety, a series of status indicator beacons can be provided to allow personnel to “see the danger.” Green lights can be illuminated above the roads that are isolated, earthed, and interlocked, clearly demonstrating to staff that the road is safe to work on. 

Railway warehouse operator opens a secure access door
Zonegreen DPPS installed in a railway maintenance and safety warehouse

Advanced Overview and Traceability

Zonegreen’s depot manager SCADA software provides a graphical overview of the status of the DPPSTM, displaying key information to make operations quicker and easier to implement, ensuring safety systems are used at all times and offering comprehensive traceability. 

Using a convenient Microsoft Windows format, Depot Manager can be configured to carry out the following operations:

  • Display the location of personnel 
  • Record all aspects of depot protection 
  • Display status of plant and equipment 
  • Complete remote movements on the SMART DPPSTM
  • Enable remote diagnostics to be completed

The innovative software can also be linked to other equipment, such as lifting jacks, bogie drops, train washes and wheel lathes to show their status. 

Additional slave depot manager screens can be installed at further locations within the depot to display the graphical overview. 

Zonegreen SCADA sofware display on a laptop.

What are our customers saying?

“At Wimbledon Traincare depot, the new Smart DPPS System has given us a more reliable form of Depot Protection that helps us to keep our depot safe.”

Fleet Facilities Manager South Western Railway

“Zonegreen are a fantastic company to work with. From the office staff that deal with organising reactive call outs, service visits and extra works quotes to the engineers that are knowledgeable and personable, the company are a pleasure to work with.”

Lead Engineer Central CBRE

“A company that has never let me down. Responsive and professional.”

Programme Manager Network Rail

“Safety comes first at Chiltern Railways and Zonegreen’s Depot Personnel Protections System is helping us achieve that at Banbury.

Engineering Director Chiltern Railways

“Zonegreen’s cloud technology has transformed our maintenance management process. It is important to share and disseminate maintenance date to different locations in a convenient way and the Zonegreen Software enables users with various levels of access to log in from anywhere.”

Fleet Operations Manager Alstom

“We at Alstom would highly recommend Zonegreen services, they are very efficient and informative and we have never had any issues.”

Facilities Coordinator Alstom