Re: NRC <> Brisbane to Sydney safeworking.

["David Proctor" <daproc.spambait@umpires.com>]

I agree, Michael - I was just paraphrasing Ebens post.

What p*sses me off is that people say it is unsafe because it uses
computers, which muck up/does not use signals/relies on drivers to follow
instructions - when all of this applies to current systems. (I know, there
are signals at unattended crossing loops - but drivers are often REQUIRED to
go through these at stop.

David "The Doctor" Proctor
daproc.spambait@umpires.com

Michael Walker wrote in message <911215053.332815@woody.hotkey.net.au>...
>>What if the computer suffers a power out for a fraction of a second and
>resets.
>>it then boots up and issues an oerder for a train that is heading for the
>train
>>it issued an order to before it went down.
>>
>>and computers do make errors. what if it gets a fualty byte in it's memory
>and
>>that corrupts the data been carried?
>>
>Without knowing for sure how cheap and nasty the computer systems used for
>present safeworking systems be they CTC or SAW, a lot of these errors can
be
>avoided. If a computer suffers a power out for a fraction of a second, I
>presume the UPS installed would keep the PC running until either the power
>resumes or it can be safely shut down.
>
>When it is rebooted, I presume the database of logged track orders would
>come back on line too and take note of where trains are supposed to be and
>not issue conflicting orders.
>
>As for corrupt data, I would assume that if it is on the hard drive that
>whatever system is set up for mirroring the hard drive be it a redundant
>drive or redundant server would use the correct data. If a redundant server
>is running, that would also fix your memory (and probably your rebooting)
>problem.
>
>I think I can safely assume that a computer system is just as reliable as a
>manual system from a fault tolerance point of view. Indeed, I would think a
>computer safeworking system is more reliable as it won't permit ANY
>incorrect moves if set up correctly, unlike a manual system. I know one
>station that shunts trains without the driver always having the staff, even
>though they need to go up and back part of the single line. The reason
being
>that when the train gets to the yard, the driver has to walk back to return
>the staff. The driver can't be bothered and the station staff get annoyed
>because they have to wait for the previous train on the single line to get
>to the end before they can get a staff and then hold up the next down train
>whilst they shunt. If the timetable is running behind, it creates all sorts
>of problems, then Metrol give them a please explain. Plus it makes the
>current timetable difficult to keep.
>
>So when the driver gets to the yard, he gives a toot and the staff is sunk
>by station staff (assuming it was removed at all - in this case the driver
>relies on the fact that the safeworking officer won't release another staff
>whilst he is on the single line). Is this a good example of the safety of a
>manual safe working system?
>
>