Posted by: Ian Angell
On Saturday 12th July, between 5.30am and 9.30am, at least 60,000 passengers who swiped their Oyster Card, Transport for London’s pre-payment system, had them corrupted. To avoid rush hour chaos on Monday, bus and tube commuters travelled for free if their cards registered an error.
So the Oyster Card system failed. Surprise! Surprise! The only property that systems have in common is that THEY ALL FAIL … eventually. It’s not a question of if, but when. And the bigger the system, the greater the opportunity of failure.
I and colleagues at the LSE tried to warn government ministers about their national ID card scheme. All we got for our trouble was slander and abuse. Such offence is typical of those who subscribe to the “pixie dust” school of technology: computation is a magic substance to be sprinkled over problems, that, hey presto, vanish.
Systems are much more like a life form: they are entropic, they degrade over time. In the case of databases, they pick up errors, and then data error compounds data error. For instance the DVLA in Swansea admitted in 2006 that a third of entries contained at least one error, and that the proportion was getting worse.
It’s caused by the complexity in the interaction between computer installations and human activity systems. We've all had encounters with computers getting it wrong. For years the banks insisted that ‘ghost transactions’ with their ATM machines were frauds by cardholders, when they were in fact system errors.
Usually the minor day-to-day problems with a system are resolved by a sensible employee, rather than by the managers who administer the system. There's a duty of care for the company to take bus passengers home when they find themselves stranded in a remote spot because their card has unexpectedly run out for whatever reason - especially given that there is no display to show how much is left on their card when they "touch in" on a reader in the middle or at the rear of a bendy bus, or on the card itself. The fact that the cash fare is exorbitantly more than the Oyster fare, bullying any regular traveller into choosing the Oyster, reinforces the need for an on-card readout.
This does raise the question of whether there are other problems with the Oyster Card, but on a much smaller scale. TFL couldn’t deny this weekend’s shambles, but can we be absolutely sure that no previous case of fare dodging was a system failure?
Wednesday, 16 July 2008
No Pearls in this Oyster
Posted by: Ian Angell