Waihola Marine director Rob Hand alerted the NZ Transport Agency to a split macrocarpa next to the southbound highway about 1.5km south of Milton in February.
He said although the tree first became damaged during a storm in October last year, its hazardous nature only became clear during the recent summer, as a partially detached 6m section split further and began to change colour on drying.
When he contacted NZTA, the agency's response had been ''more talk than action'', he said.
''They've been very good at talking the talk and reassuring me something is being done, but each time I drive past it's still there, unaddressed.
''Given the terrible road toll of recent months, it's just something I feel the need to be proactive about. If we can save even one life, it's got to be worth a couple of hours' work, surely?''
Mr Hand said initially the agency and its contractor, Downer, had informed him the tree was on private land, and therefore the responsibility of the landowner.
Subsequent communications had indicated NZTA would take independent remedial action if the landowner failed to address the situation.
However, more than two months after first bringing the issue to NZTA's attention, Mr Hand said he had run out of patience.
''I used to work in forestry and it would be a quick job for an arborist to fix up. I've seen a gradual deterioration in the split since February, and if that comes off, it could bounce half way across the highway and cause a nasty accident. I'm afraid it's a case of 'talk is cheap'.''
NZTA coastal Otago maintenance contract manager Nick Rodger said the tree had been assessed, and was not believed to be an ''immediate hazard''.
''We've had professional arborists inspect the tree since Mr Hand told us about it, and they don't believe it constitutes an immediate hazard to road users.''
The tree would be trimmed as part of ''ongoing highway maintenance in coming months''.
''We've arranged with the landowner for the tree to be trimmed, as well as a hedge to the south affecting intersection visibility, when our crews are in this area.''
That might not be soon enough, Mr Hand feared.
''What I'd like to see is nobody hurt while we're all busy talking about it. Unfortunately it's too late when the ambulance is at the bottom of the cliff.''
