I remember being so shocked at this accident. Watching the pictures on tv news left me feeling sick and numb. How on earth could this have happened?
I think it turned out that recent upgrade work in a nearby S&T▸ cabinet had not been done properly and hadn't been checked and tested. This led to big changes in the process and culture of new works being done on the railway
The report said work was being staged, couple of weekends apart. The new signalling was installed correctly, but a feed wire to the removed signalling was just undone and left loose (it was not removed because circuit was powering a part that had not been changed). Someone knocked this bare wire and it came into contact with the signals in question giving false display.
The accident came down to lazy approach of not insulating an old wire that was retained temporarily and was going to be stripped out few weeks later. Ironically had the work all been done in one big changeover as had been done in 1936 when the signalling was changed to colour lights, the old circuit would have been dead and no wrong signals displayed.
The trains did not have anti climb units (serrated panels that engage) on ends of underframes, were old mk1 design with separate underframes, no bright taillights which reflect off the rails (just red bars in headcode box), and had no emergency radio to signallers unlike today. So lot has changed.
If I recall the events correctly.
The re-signalling works was being carried out in the main by
BR▸ S&T teams the small install team BR had was bolstered by overtime by local S&T maintenance techs. This was not uncommon at the time.
The wiring had been disconnected from a relay style referred to a "jam jars" these relays were a glass jar (later ones plastic) which allows the contacts to be observed, however the terminal studs come out of the insulated "lid". During the staged works wires had been disconnected and held up to the wiring harness with PVC insulating tape, possibly having been used before (budgets were tight in BR days and I am not joking I was working at the time for BR as electrician on the WR often getting essentials such as insulating tape, hacksaw blade etc has a challenge)
The insulating tape came unwrapped and the wire dropped onto a relay terminal. The terminal connections had not been cut off or insulated with tape, if it had been taped the tape had fallen off.
There were a number of things that all came together to cause this disaster
The excessive working hours of BR staff tolerated and indeed expected by senior BR managers and engineers in what we now call safety critical rolls.
No clear identification of out of service equipment / wiring, now a colour scheme is used, (green = to go / remove, blue = modified, red = new to be installed).
The use of PVC insulating tape to hold up removed wiring, not insulating disconnected wire terminals and terminations, today clear neoprene tubing is used to insulate out of service wire terminal; were possible redundant wiring should be cut back / removed at the time it is taken out of use.
No "independent" checks of the work carried out before return / entry into service, the S&T now have SMTH (Signalling Maintenance Testing Handbook) and STHB (Signalling Testing Handbook) and the implementation
IRSE▸ Licencing (Institution of Railway Signal Engineers) for all involved in railway signalling design, maintenance, installation and testing