TPWS Flashcards
What does TPWS stand for
Train Protection and Warning System
What is the purpose of TPWS
To stop the train by initiating brake demand, where TPWS track equipment is fitted. If train has….
Passed a signal at danger
Approached a signal at danger to fast
Approached a reduction in permissible speed to fast
Approached buffer stops to fast
Where is TPWS provided
On passenger lines, at all main running signals capable of showing a stop aspect which protect crossings or converging movements
At any signal capable of showing a stop aspect on a non-passenger line, where that signal protects a crossing or convergence with a passenger line.
In the approach to buffer stops at the end of passenger platforms. Fitted approximately 65 metres from the buffer and will trigger at speed greater than 10mph
On the approach to permissible speed restrictions
What track equipment is associated with TPWS
The track equipment is made up of an Arming loop and a Trigger loop.
TSS (Train Stop System) the TSS is mounted in the 4ft. The arming loop and trigger loop are together. It is energised when a signal is at danger and de-energised when the signal is showing proceed.
OSS (Overspeed Sensor System) The OSS loops are placed separately at varying distances apart according to the permissible speed they are set to.
When the train passes the arming loop it starts a timer on train. If the train reaches the trigger loop within the set period, the on train equipment will initiate brake demand.
What TPWS on train equipment is there.
Receiver- located under the train near front bogie to detect the transmitter
Control panel - containing lights for Brake Demand, Temporary Isolation/Fault, Train Stop Override.
Acknowledgement button - used to acknowledge brake demand on standard panel
Temporary Isolation Switch - mounted out of reach of the driving position. Allows driver to perform certain movements without causing a brake demand. Passing 2 or more danger signals, TBW, ESW, Propelling or within T3 Possessions
AWS/TPWS Full Isolation Switch - mounted out of reach of the driver. It may be necessary to isolate the TPWS if there is a fault with the train or if the train has stopped over a magnet or TSS loop. Only a fitter can reinstate, train has to come out of service.
Can you start your journey from a maintenance depot with TPWS not working
A train must not be allowed to start a journey unless the affected cab is not required to be driven.
Can you start a journey from somewhere other than a maintenance depot with TPWS not working.
You must tell the signaller and carry out all instructions given
What must you do if the TPWS fails during a journey
Stop the train immediately, tell the signaller, do not move the train unless authorised and carry out any instructions given.
Does TPWS prevent the driver from having a SPAD
No, it is designed to mitigate against the consequences of a SPAD by stopping the train
If you have a TPWS brake demand what must you do
Bring the train to a stop,
Full service brake
DRA on
Selector to neutral
After acknowledging the brake demand the brakes release after 60 seconds (press the brake release and relevant action on enhanced panel)
You must have permission from the signaller
