Nothing is perfect

[aussiesteve]

G'day,
Just found this accident report at the NTSB.
https://www.ntsb.gov/investigations/...reliminary.pdf
Whizbang PTC (positive train control) obviously don't solve all dramas.
Any system can become a failure, as in this case.
I would imagine that the FRA will now mandate more stringent rules regarding the isolation of a faulty system.
Steve.

[Beeyar Wunby]

Hi Steve, you've dug up another interesting one.

Originally Posted by the NTSB report

Chessie instructions specify that for trains operating with active PTC, crews performing pickups, set offs, or other switching activities including shoving movements must use restricted mode for the PTC system. In restricted mode, the PTC system allows train movement at restricted speed and no longer automatically stops the train before it can violate a red (stop) signal.

AND

Preliminary event recorder data indicated the train speed never exceeded 20 mph (upper limit threshold of CSX restricted speed rule).

So there's a significant chink in the PTC armour.

Mind you, most safety systems have to be overriden at some point. Our own TPWS has to be isolated when performing Temporary Block Working (ie, passing 2 or more signals at Danger). The Rulebook states that when you stop after completing the movement you MUST reinstate it. But if you forget, you can run around all day without it until you shut the desk down (take your key off). TPWS will then become active the next time the desk is started up.

I've heard of at least one SPAD over here where a guy failed to put the TPWS back in.

I suppose they could put in a device that automatically reinstates it above 50mph (the maximum speed allowed for wrong direction working during Single Line Working), but then some trains never get above 50 all day.

Or cheaper still, a little voice announcement every so often saying that TPWS is isolated - although that might drive you up the wall after a few hours!

As I tell my boss on a regular basis, whenever humans are involved somebody will screw it up sooner or later.

"There, but for the grace of God, go all of us"........

Cheers, BW

[aussiesteve]

G'day BW,
Bring back the Good ole Days.
No stinking computer in the cab.
And, yer driver saying to you, "Keep pressing that button son, I'm gunna rest me eyelids for a while".
Slogging it out on a full load up a long climb, the hogger cranking back his seat and indeed shutting his eyes.
The tailgunner would likewise be snoozing back in his caboose.
Then as soon as the loco revs altered as the top of the climb was reached, he would jump awake and begin to shut off power.
But, after the Beresfield prang in 1997 our vigilance system was altered to become random.
No longer could you simply keep thumping the button.
I was the sole union rep battling with the adaptation of the vigo system.
At the time, all other union reps were occupied with the Glenbrook inquest.
One of the results of that inquest being the implementation of the Train Stop on sticks on the Blue Mountains.
But, even today, that system is not applied to locomotives, only emu and dmu dingi.
The big knee-jerk result was the alteration of our signal rules.
Previously, an automatic stick could be passed at STOP after halting and attempting to make contact.
If unable to make contact with the signalman, then waiting one minute and proceeding at Caution speed (25 kph) until passing TWO green indications.
The knee-jerk implemented, ABSOLUTE and PERMISSIVE sticks.
And, only the signalman could instruct as to which was which.
SO, NO communication and NO GO.
It was a nightmare for a period until common sense prevailed.
Today, in cab radio communication does provide a much better system.
But, it is NOT perfect.
And, there are THREE individual systems, depending upon which network you are travelling through.
I enjoyed the good ole days.
Steve.