Brian Rudman: Predicting bus times still a hit-and-miss affair

COMMENT

A couple of weeks back, I decided to treat myself to a trip home in the Link bus. But when I got to the stop, the electronic signboard warned that the next one was not due for 13 minutes, so I started walking. I was barely 100 metres into the trek when a sleek grey Link sailed past.

A few evenings later, the signboard at the corner of Queen St and Victoria St said the next Link was nine minutes away. Once again I decided to hoof it. This time at a pace, if the signboard time-keepers are to be believed, that would have got me into the Athens Olympic squad.

In the five minutes it took me to sprint two stops up the hill, I'd managed to widen the time gap between me and the approaching bus to 11 minutes. When the next Link turned up I have no idea. Luckily an 005 arrived and rescued me from the madness.

Perhaps, suggested a helpful colleague, the Link bus had been going backwards.

As an experienced Link patron he has a tale or two of his own to tell. Just yesterday morning he'd arrived at his Parnell Rd stop to be greeted with the depressing news that the next buses were not due for 28 minutes, 29 minutes and 38 minutes. Hardly had he time to check his wallet to see if he had the taxi fare when up pulled a missing Link. Missing as far as the electronic wizardry was concerned anyway.

This is the wizardry that a report to today's meeting of the Auckland City Council's transport committee says is working well enough to progress to stages two and three. That involves expanding the system to bus routes throughout the city.

The report concedes major teething problems with the system. When the signage was progressively activated last Christmas there was a "high percentage of 'missing services' (around 20 per cent to 30 per cent)" but most of the problems were "resolved" and "missing services are now down to around 3-4 per cent".

Which can only mean I must attract the most awful luck. Always down there below the margin of error am I. Still, I do hope the councillors, in reading the report on this troubled $6.9 million publicly funded project, do note the trepidation expressed in the fine print, before they agree, as recommended, to progress the contract to its final stages.

Auckland City awarded the contract to Saab ITS in March 2002 to develop and implement a combined signal pre-emption system - which enables buses to get priority through traffic lights - and a real time passenger information system.

The latter involves an electronic communication system which enables bus-stop signboards to broadcast the arrival times of approaching buses.

Government funding agency Transfund is the biggest backer at $3.2 million, then Infrastructure Auckland with $3.1 million and Auckland City at $600,000.

By the time the trialling began late last year it was already a year behind schedule. Even now, in recommending the project continue, the officials are tempering their hopes for the system, with a worrying degree of caution.

They begin by extolling the success of the signal pre-emption system, claiming it is saving "an average 11 seconds per intersection or eight minutes per trip".

Collapses in the system to begin with were described as "an isolated incident".

They do admit, though, that "although hardware reliability is meeting the contract requirements there have been underlying concerns with component reliability, which Saab ITS is addressing through extensions to warranties and review of components."

An external audit of the system, by Parsons Brinckerhoff, concludes that the system would have to continue "to run with far fewer issues" before Saab should be allowed to proceed to stage two.

Of course for all the glowing public relations spin surrounding the system, Saab privately knows how difficult the reality of predicting the arrival of the next bus would be.

In a paper entitled "Measuring bus prediction systems accuracy", Saab ITS technical marketing manager David Panter admits "given the number of parameters involved and the way the bus prediction systems work it could well be argued that an accurate prediction is more an oxymoron than reality".

This is rather different from the Saab PR which hails the system being employed in Auckland as "sophisticated technology that delivers pinpoint tracking of vehicles ... " Not yet, it don't.