Police have defended their handling of a harbour bridge crash which closed three northbound lanes on Saturday, causing huge traffic jams that crippled the city's transport system.
Inspector Claire Humble said disruption could have been even worse had police not abbreviated their crash scene examination.
Investigators had decided to make do with marking and photographing the scene rather than conducting a survey involving advanced mapping equipment, she said.
Even then it took three hours to clear, which she defended as necessary to gather enough evidence for any court cases over the crash, between two motorcyclists and a truck.
"I think the officers dealt with the incident as thoroughly and professionally as they could have under the circumstances. It's that balance between scene examination - doing that thoroughly - and keeping the disruption to a minimum."
Mrs Humble said police might still return to the scene to conduct an advanced survey.
She understood one motorcyclist was in a general hospital ward, but the other remained in a serious condition.
Police crash scene investigations drew heat when a judge criticised police for sweeping away evidence after three young women died in a wreck in Southland in 1995.
Controversy over technology available to police flared after a crash on central Auckland's Fanshawe St exit from the Northern Motorway in 2004, which created a traffic jam almost 20km long.
Mrs Humble said the difficulty on Saturday was the extent of the crash scene across the three lanes.
"Because there were motorcyclists involved, it's quite challenging, because the officers were looking at skid-marks and gouging in the road of fabric that might have come off the motorcyclists," she said.
"What you have to appreciate is the serious crash investigators have only one shot at getting all the information - the minute that road is reopened and cars are driving through the scene, all their evidence is lost."
The investigators considered re-opening one of the lanes early to improve traffic flow, but decided it would have been too dangerous working so close to moving vehicles.
Transport Agency highways manager Brett Gliddon said that was among considerations in deciding against trying to use the bridge's moveable lane barrier to increase capacity for northbound traffic.
Traffic had built up too heavily around where the machine would have had to manouevre, and "rubber-neckers" were also causing congestion in the southbound lanes.
Saturday's incident would have no bearing on the agency's summer maintenance plans which will include closing the bridge's two northbound clip-on lanes for resurfacing from Boxing Day to January 8.
Read previous article: Auckland traffic delays 'a freak accident' - PM
Mr Gliddon acknowledged a third harbour crossing, planned for 2025 to 2030, would have eased congestion on Saturday but said early relief would be gained in 2017 from the completion of Auckland's 47km western ring route as an alternative to State Highway 1.
Meanwhile, Prime Minister John Key has ruled out earlier construction of the next Waitemata crossing, for which the Government prefers a $4.8 billion pair of tunnels.
"I don't think you just start building that tomorrow because there was an accident on Saturday afternoon," he said. "For the most part it works well."
Help on its way
Transport Agency expects to complete most of the 47km Western Ring Route alternative to State Highway 1, from Manukau to Albany, which will include the $1.4 billion Waterview tunnels and $600 million of new lanes and related improvements to the Northwestern Motorway.
Government intends to build a third Waitemata Harbour crossing, a $4.8 billion pair of road tunnels, possibly "future-proofed" for rail, east of the Harbour Bridge. But the Transport Agency says the main purpose will be to cater for the growth of Auckland, with extra "resilience" simply an added bonus.
-additional reporting Isaac Davison