Depot Protection System

A Depot Personnel Protection System, commonly referred to as Depot Protection System or DPS, is a system designed to protect staff and equipment by ensuring the safe and controlled movement of rail vehicles into and out of train maintenance depot, a process sometimes known as shunting. This allows train maintenance operations to be conducted without endangering the safety of staff, and damaging other maintenance equipment in the depot.

The most important asset in the depot are the people working there, therefore the depot protection system needs to deliver the highest level of personnel security.

A depot protection system consist three basic elements:

• the signaling systems that give the train driver permission to either enter or exit the maintenance building,
• a method of warning staff when trains are moving or about to start moving
• some method of physical protection is highly desirable and this may include a wheel stop or derailer. These, when raised, would intentionally derail any unauthorised train attempting to enter the depot, thereby protecting staff and equipment in the depot.
• signal control panel which provides some form of control procedure for an operator to accept a train into the depot, or to release a train from the depot.

Traditional system

Traditionally protection to a personnel working in the depot is provided using padlocks. Staff would fit these padlocks onto the signal control panel before starting work. With the padlocks in place, it would not be possible to access the control panel to set the driver signal to proceed or lower the physical protection.

Unfortunately although widely installed these simple padlock systems do have some draw backs. Padlocks often had to be destroyed when staff forgot to remove them at the end of the working period, in which case they would have to be cut off and it is a slow procedural system with poor traceability in the event of an incident. This lead to the development of more advanced electronic systems that overcame these weaknesses.

Advanced personnel protection system

The most technically advanced depot protection system comprises of a number of microprocessors-based control panels installed in a distributed communication network and operates using electronic identification keys or token in place of padlocks, where the users' details are stored electronically on these portable memory devices. Before starting work the staff log onto the system at the nearest control panel to "apply personal protection" to themselves while they are working in the depot. The action of logging onto the system will prevent train movement to be authorised by inhibiting the lowering of physical protection and clearing of driver signals.

Unlike the traditional system where staff often have to walk the length of the depot to reach the master signalling panel to install his padlock, staff can "logon" to the system from control panels at a convenient location. Because it is easier to apply personal protection and monitor its application staff are much more likely to use the electronic protection equipment and not short cut the safe working procedure as was the case with more traditional systems

Advanced depot protection systems aim to provide performance monitoring software. This helps identify operational efficiency savings and provides full traceability in the event of an incident.

Modern protection system installed today’s depots may consist of the following equipment:

• Operator control panel
• Shunt signals
• Derailer
• Treadle/Track switches
• Audio visual warnings

Operator control panel

The operator control panel is installed inside the entrance door of each road. These panels control movements into and out of the depot. Staff accesses the system using a data key that stores their personal details and replaces the traditional personal padlock in old safety systems.

Shunt Signals

Shunt signals are located at the entrance and exit of the workshop to indicate to the driver whether it is safe to proceed. Inbound signals are mounted on low level galvanised stands, whilst outbound signals are placed at cab height on galvanised stands or standoff brackets.

Derailer

Derailers are electrically powered. They are the ultimate safeguard in preventing vehicle access and are fitted to tracks approaching the depot.

Treadle/Track switches

Treadle/Track switches are fitted to the tracks approaching the depot to warn operatives of a vehicle’s approach. They are triggered by the passing wheel and can be used to indicate that a vehicle is waiting.

Audio visual warnings

Audio visual warnings are beacon signal lamps and klaxons which are installed above each track within the depot and within the pit and are used to display the status of the protection system.