I wonder what the 'Skid Distance' is for the current fleet of Suburban rolling stock is?
Once past this 'Stop', there is still nothing to stop a Driver from opening the 'throttle' if he/she was of a mind too.
Not inconceivable when you consider the missing flight MH370 and that Pilot who waited until the Captain left the cockpit and dove into a mountain.
Committing suicide by driving a Train into a set of Stop blocks at 20 KPH isnt likely to succeed but People can do weird things during a mental episode.
As an additional safety feature, I am sure there are electronics available today that once passing a 'location', it would not allow the Train to increase its speed and could monitor the speed and if its too high, cut the power also applying the Brakes if this is not already being done so by the Driver.
This would only need to be functional at Dead ends and maybe where Derails turn a Train into an unsafe area.