I hate it when people use jargon or acronyms when they know other people won't know what they stand for.
Yes, I'm looking at you project.
RAIB, rail accident investigation branch, investigates accidents and publishes their reports and recomenndations,
AWS, automatic warning system that alerts drivers to colour/aspect of signal in front of them, bell and klaxon, now being changed to more electronic sounds,
TPWS, automatic train protection system, as above but more expensive, both can be isolated by the driver,
SPAD, signal passed at danger ,eg a red aspect,red signals control the stopping of a train before junctions, the train in front, conflicting movements by other trains, single line workng, and terminal stations and other incidents.
Passcom, passenger comunication device, either a handle, lever button or chain, used to comunicate to the guard/driver the train needs to be stopped, the driver can over ride the alarm, but should apply the emergency brake in a station environmnet if activated, probably because someone is trapped in a door or fallen under a train.