Gee, it seems another one sees the elephant in the PTS / ETRMS room. Not to mention all the rhinos, A_holes and alligators in the room that are currently being ignored - worldwide. But ya still gotta watch out for them gators!

All active countermeasures against hazardous events such as PTS, ETRMS, CBTC etc; can and will sometimes forget things, especially if a reboot is needed. You might call this "loss of situational awareness", just the same as when a human engineer forgets something or looses track of where he is. Note that the life and death outcomes are no better when the equipment looses awareness than when a human does it. Death by machine error is still death.

Passive countermeasures, such as all modern types of track circuits and modern ATC/ATP equipment on the other hand, do not try to remember a thing. Does not need to, as it is designed to every half second or so, freshly discover anew for itself, whether all potentially hazardous conditions are in fact in a safe state or not. It is further designed to be capable of displaying a less restrictive aspect only after all required conditions have been proven to be in the safe state. Any failure, passively by default, reverts any aspect or lock, to a more restrictive state.

If a reboot is needed in a passive system (most existing electronic railroad hardware is passive), it thus comes up with all measured conditions displaying their most restrictive state. Only as each is proven to be in a safe state, do the aspects and safety locks become less restrictive.

In the case at hand, that of dynamically set speed restrictions (you must type in the speed and mile post limits), the very nature of the requisite logic makes it very difficult and probably impossible to make this actually safe.

Instead, at some rapid transit agencies I have had experience with, contiguous short sections of track were pre-programmed as fixed restriction zones, which could be remotely set or released through a precise manual protocol. Any failure then, would passively drop affected sections to the default restricted state until deliberate manual intervention occurred - which is what would have set any intended restrictions in the first place.

But this is not how the ETRMS in question (and PTS) does it; because having a finite set of passive speed restrictions is not dynamic, as was envisioned. Nor is it convenient during fault recovery. But it was safe. Less restrictive aspects were still not possible until proven safe. And it was about the best that can safely be done.

It is entirely too bad that those pushing CBTC systems such as PTS & ETRMS, simply do not seem to have even a basic understanding of the absolute, strategic, and tactical realities in the netherworld of safely governing train movement. Or they just ignore them as ETRMS designers did here.

Or perhaps they think that using fancy new and/or exotic technologies will somehow excuse them from taking into full account all those absolute, strategic, and tactical realities; presuming that 150 years of human experience and progress is just not important anymore.

Such is the profound ARROGANCE of the modern generation. But ya still gotta watch out for them gators! Failing to remember the lessons of railroading's bloody history could bring to pass a repeat. Already has to some degree in some quarters of the world - even in Europe.