OPB,

Well said.

Any of several integrated ITS train control system concepts would work, with or without GPS integration, as one source of locational back up referencing. But, as you point out. We often are told try to reinvent the wheel from scratch with "new" technology, which often fails to take lessons learned into account. Or, far worse, we all too often seem to try to figure out how to "adopt" the vendor driven proprietary system, regardless of merit, of those making the biggest campaign contribution to the Members of Congress....

I'm semi retired these days, and won't take certain work anymore. So I am a little freer now to say more about how the system, all too often, really appears to work.