It may be worth taking a long and close look at the WSP of these trains under different conditions. It wouldn't be the first time a WSP system would impact braking performance more than it should in a small part of it's operating envelope.
The reason newer units add additional brake force was due to an 80s directive on driving standards: Drivers were expected, on a good railhead, to brake in step three (full service) at their brake point and release only for final coming-to-a-stand adjustment. Units built after this time give ~20% additional brake force in emergency to provide a buffer if the driver misjudged his braking. Obviously this is not how trains are driven today!
As a train driver I can only judge the behaviour of the first vehicle or, in the worst case, the behaviour of the axle with the sensors for the speedometer. The conditions can change considerably over the length of the train. Releasing all the brakes does not necessarily lead to an improvement in braking force. WSP is mainly a tool to prevent damage to the vehicle, not so much to shorten the braking distance. In principle, sufficient effectiveness of the brakes must be demonstrated under various circumstances during the vehicle acceptance process. Many vehicles would still have some reserves in terms of braking efficiency in dry weather, but do not utilise them because the requirement has already been met.
Other than sounding the horn, but I doubt that would have been audible in a train coming the other way. Might be appropriate if the runaway were approaching a station or level crossing.
I agree, I am also only aware of what's going on with the first vehicle if judging entirely based on the gauges. You can, however, feel when the train is not at all or barely decelerating (which means all or most wheels are sliding).
As I said earlier in the conversation I have when the brakes have been released and brake gauge continues to read zero applied a little bit of power to get the wheels turning,get a reading on the speedo and start braking again.This was on approach to line speed reduction,signals and station stops I then follow orders so no come back on myself.
Yep I see no issue with that myself. Ultimately you want those wheels to be turning again and if you're in emergency that's not gonna happen until railhead conditions improve.
I have no empirical evidence sorry, not even sure how you’d measure this, it’s just from my experience of driving over the years. WSP was a rarity years ago but from perhaps 10 years ago it started to be retrofitted to a lot of the ex BR stuff I drove.
Emergency generally activates the sander too, whereby full service brake does not. Also shows on the OTMR the driver was aware of the requirement to stop asap.
Last time I did this I informed the relieving driver another long in the tooth guy like myself he said he does this as well,I may be wrong on this but the way I look at it is you can't brake a wheel that's not turning.
But going against company policy is a big no no. I've seen drivers do this and receive tea and no biscuits.
Indeed that's why I pick and choose doing this carefully.
It's actually been quite a good year where I am!
He could have sent an emergency message on his train radio.
Interesting questions, but which need to be answered against the operating instructions crews work under.
I don't think derailment follows running through incorrrectly-set trailing points, you just break the end bit off the switch blade...
Step 1 - no sanding.
Plenty of reported adhesion issues up and down the network, plus some units lost on track circuits. Remember that this was just after a very windy day so a lot of leaves may have been blown out of the trees.
Are they sprung, or locked in position?
Locked points, the loop is bi-directional.
That seems logical to to me. If the wheel is already not turning, gripping it harder will do nothing. It will make no difference to the adhesion. Ideally the WSP needs to keep the wheels on the cusp of slipping but you might still run out of track before it manages to stop the train. Isn't that what happened with the class 165 at Slough back in the 1990s?
There's two ways to look at this really, for example in the case of Salisbury, once the driver knew they were going to pass the signal, an earlier REC (I must admit I can't recall if there was one or not, I try not to remember that night at work!) could have got the driver of the GWR to stop in a potentially more vulnerable place than it did.
Points are designed to be run through without (much) risk of derailment. For traditional point machines and mechanical installations, that usually means bent or broken thrust, lock and detection rods. In clamp locks, the force on switch rails overcomes the clamping force. For the HPSS, manufacturers had to incorporate a 'frangible link' to get approval. In all cases, the point mechanism is broken in some way after a run through and needs repair before being placed back in service.
