Dr Zarkoff Wrote:
-------------------------------------------------------
> > a cheap CTC signal system that did not show
> siding occupancy upon entering.
>
> Not having track circuits in sidings was an
> economy move by the purchasing RR.
>
> The WP chose to use a standard CTC system with
> unbonded sidings, so entering a siding was
> authorized by a restricting indication (red over
> lunar), and this indication was displayed
> regardless of whether the siding was occupied or
> not.
>
> On the SP, most sidings within CTC were bonded, so
> if the siding was unoccupied, you entered on a red
> over yellow (which doesn't require restricted
> speed). If it was occupied, you would get red over
> red (stop) signal, and the DS had authorize you
> verbally to pass the signal for entering the
> siding (at restricted speed).
>
> > WhenBART first was running M-F only and closing
> at 8PM, they had corrosion based issuesbetween
> wheels and rails. Mondays when the tracks went
> live again, another recalibration.
>
> Before starting revenue service, BART was running
> test trains, and they got everything working fine.
> Then they turned on the fluorescent lights in the
> stations, only to find that these created so much
> inductive interference in the "track circuits"
> that it rendered the system virtually unusable.
>
> The corrosion problem arose because overnight
> moisture would condense on the railhead creating a
> monomolecular layer of iron oxide. You couldn't
> see it, but if you wiped your hand over the
> railhead, you would find a film of rusty moisture
> on your hand. This layer would act as a half-wave
> rectifier between the wheel treads and the rails,
> causing track occupancy detection failures.
>
> > IINM, they installed scrapers on the wheels.
>
> And the SOARS block system. The scrapers are long
> gone, but I don't know about SOARS.
>
> > Bonus weirdness: SLACK the Stanford linear
> accelerator found that after Fri evening shutdown
> of the third rail energy, they had to recalibrate
> even though they were miles from any BART tracks.
>
>
> "SLAC". In its Beale St tower, PG&E had a
> real-time electrolysis map of the Bay Area. The
> rails in BART's Hayward Shops are insulated from
> the rest of the system, and the mere act of
> shoving a car into or pulling one out of these
> shop tracks using BART's equivalent of a
> Trackmobile would show up as a momentary blip on
> this map.

Thank you good Doctor. As usual, you are always the best source of technical information on AP... There's never a post where I don't learn something from you that I either didn't know, or just had forgotten over time.

And your experience with how the A signals at Bertran should have worked is the same recollection as mine... And with cars stored, it should have been locked into a red over red indication... Just by stopping to flag the signal at restricted speed, they would have seen the cars and nothing would have happened, except for some minor embarrassment and more headaches for the dispatchers...

The reference to the purchasing railroad reminds me of those buttons that came out right after the SP/UP merger and the immediate "meltdown", that an SP friend, still "enslaved" at the UP, gave me, that said: "I was not always stUPid".