29 June, 2010


On not inspiring confidence

Oh they used to laugh at me
When I refused to ride
On all those double decker buses
All because there was no driver on the top
Unlike Joni Mitchell's "twisted" subject, I have o'ermastered this entirely reasonable fear and can now ride with complete confidence even on the Dockland Light Railway's entirely driver-free trains.

The Passenger Service Agent (PSA), incidentally, has even less involvement with the driving of the DLR train than would at first appear. In normal operation, he doesn't even get to start the train. The train (or perhaps more precisely its controlling computer, presumably back at Poplar) decides when it is ready to leave. (This, if you've ever ridden the DLR, is the sonorous bong followed by the green light coming on at each of the distributed control panels. It's the train saying, "OK, let's go".) The PSA merely confirms that it is safe to start and agrees to the request.

And it's all damned clever stuff and it works brilliantly.

So why was I suddenly so uneasy when I saw the cop-out message
Check front of train for destination
on the platform displays at Greenwich? Yes, intellectually I understand perfectly well that the train driving and signalling software and the software which drives the platform information displays are separate systems, engineered to totally different standards.

And so they should be. In my career at Megacorp Inc, many's the entertaining argument I've had with the ivory-tower monkeys, trying to persuade them that a database application that was in active use only six weeks a year and which even during its bursts of admittedly frantic active use could nonetheless tolerate at least one half day of unscheduled downtime without fatally disrupting the supported business process, that such a system did not actually justify hot-standby with automatic failover plus centrally-managed out-of-hours scheduling of maintenance, even if their arse-covering, "everything is mission-critical" standards did demand it. I could, and did, shut that particular box down for two days at a time during the "off season" and nobody even noticed.

So no, intellectually with my engineer's head on, I don't expect the platform display systems to be totally reliable. or even fail-safe (imagine a bulb and its backup failing in a platform information display and the whole railway shutting down).

But emotionally, with my passenger's head on, somehow I do expect my automated driverless railway to be seamlessly perfect, and the reactive layers of my mind tend to equate
No information available. Please check front of train for destination
Welcome to the beta version of DLR 3.0. If you are killed in a collision or crash, please complete an error report form and hand it to the Passenger Service Agent, or his ghost as appropriate. Your co-operation in helping to improve our software is valuable to us.
I remember sitting on a Jubilee Line train a few years back. The train was standing at either North Greenwich or possibly Canary Wharf and was not going anywhere. Then the driver came on the tannoy to announce that the carriage lights would be going out briefly as he was going to try to "reboot the train". Power-cycling a recalcitrant tube train to get it started: that doesn't exactly inspire confidence either.

Complicated old world, innit?

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