Rotten oak tree that crushed four cars in Auckland Domain passed checks

Tofik Mamedov was shocked to find the damage done to his car, which is not insured. Photo / Jason Oxenham

Council staff say tree’s internal damage did not show up in ‘extensive investigation’

A two-tonne tree branch that snapped from a 150-year-old oak tree, badly damaging a row of parked cars in Auckland Domain yesterday, was probably rotten but was "extensively" checked by council staff last year.

About 1pm, the tree appeared to split in half, slamming the 15m limb on to four cars parked beneath it. The cars' roofs were crushed and windscreens shattered. No one was injured.

Council parks manager Mark Bowater said the limb that "failed" stripped away part of the trunk of the tree, revealing internal decay.

"That appears to be the cause of the failure," he said.

Two of the four cars damaged were not insured, but the council would not foot the repair bill, Mr Bowater said.

"The limb that failed had no visible sign of decay, so its collapse was not predictable, and council does not believe it is liable to pay compensation. We expect all car owners to insure their cars," he said.

Tofik Mamedov's red Rover was severely damaged. He was shocked when he returned to the park.

"I couldn't believe it," he said. "Unfortunately I don't have insurance."

Firefighters chainsawed the fallen limb into pieces before it was removed, overseen by city arborists.

"We have done a lot of work to identify risks for these trees ... and we have done work on all of the trees in terms of risks that we saw," council arboriculture and landscape adviser Simon Cook told the Herald. "[The trees] are really difficult to protect and we are looking more and more at closing the car park in here."

Mr Bowater said the particular tree, and surrounding oaks, were "extensively investigated" late last year.

They were planted around 1860 and historic photographs showed they were "well-established" by 1914. "That investigation included a full visual assessment of all trees by independent specialist arborists including soil testing and invasive testing on trees where there was concern of decay," he said. "It recommended removal of deadwood and reduction of the crown of many of the old trees in the stand which was completed in November."

That investigation extended beyond the stand of oaks involved in yesterday's incident and included 206 oak trees in Auckland Domain.

Mr Bowater said the cause of the incident is being investigated and it is likely more work will be carried out on trees in the Domain to remove any risk.