[kelseyfrog]

You can literally buy derailers[1]. People will find away around this, making white paint useless. Engineers need to engineer.

1. https://www.aldonco.com/product-category/derails/

[hhh]

this is tackling regular natural derailment incidents not terrorism

[trollbridge]

Derailers are common and are placed where people are working on tracks so a runaway car will go off the tracks instead of hitting the workers.

[advisedwang]

OK, but a heatwave isn't going to buy a derailer

[defrost]

   Do NOT use where speeds exceed 5 m.p.h.

Not sure what you're thinking of, but these widgets you linked won't solve the problem of long rail sections heating up in the sun, buckling, and derailing freight trains travelling at normal speeds.

[StilesCrisis]

Why worry about memory safety? Users can literally "kill -9" anyway.