Quick question - this may be more a 'general railway' query than one specific to the 345s, but since it concerns one - during one of my journeys home this week, not a particularly late running one, the driver of the 345 I was on was for a few seconds, unquestionably speeding. As I understand it the line speed between Harold Wood and Brentwood is 70 which, by and large, the 345s run at for the majority of it due to their much higher power output, so I'm used to what that sounds like. In this case, we must have reached over 75, possibly approaching 80. Shortly following this, the brakes appeared to be fully applied but only until the speed dropped below the limit. If the driver genuinely exceeded the speed limit, I would have expected, particularly on a modern unit, for safety protocol to stop the train outright.
Could someone advise what the expected behaviour is for this scenario? I'm sure I remember hearing that what constitutes speeding on the railway is near zero-tolerance, as well it should be, so I'm kind of surprised that this sort of speed was attained in the first place, I can only assume perhaps that there's a time interval controlling it?
The only time I can recall this happening before was a few years ago on a 315, the same stretch but this time in the downhill direction, on the odd diagram Greater Anglia ran on the fast lines non-stop from Shenfield to Stratford in the morning peak using a 315. Much the same happened there, we reached what I estimated to be the low 80s before the brakes were abruptly applied, but only to continue the rest of the journey at 75. Although I realise that would be exceeding the unit max speed rather than the line, I assume policy would be fairly similar.