A "very intricate clean-up" will be required after flying metal shards punctured hundreds of car tyres along a major highway connecting two cities, bringing traffic to a screeching halt.
Some 25 kilometres of the M1 Motorway north of Sydney was closed on Friday after a truck carrying metal debris spilled its contents about 5am.
The shards were scattered along more than 20km of the southbound lanes, slashing the tyres of hundreds of vehicles driven by unsuspecting motorists.
Multiple tyres on some cars were affected, the New South Wales transport department said.
One tow truck driver said she had had a busy morning transporting cars back and forth to tyre repair shops.
"It's been non-stop," Nicole of Central Coast Auto Recovery told AAP from the highway.
"I've towed six cars by myself so far and we're taking them all to Gosford tyre shops - just lots of flat tyres."
State transport officials tallied about 145 vehicles damaged and marooned due to burst tyres.
A 20km stretch of the major arterial road connecting the Central Coast to Sydney was closed while traffic was backed up another five kilometres further north.
A clean-up operation comprised of emergency crews and sweepers was under way on Friday morning.
"It's a very intricate clean-up operation of the road at the moment to make sure future vehicles aren't affected with any debris," a Transport Management Centre spokesperson said.
"It's a bit of a slow effort before reopening the motorway from Ourimbah to Mount White"
Dozens of tow trucks have been dispatched to more than 200 drivers, NRMA spokesman Katrina Usman told AAP.
"Our patrols are able to fix (single punctures) on the side of the road," she said.
"But for cars with multiple wheels damaged, we've provided tows ... as of this morning, it was nearly two hours (to wait) for roadside assistance or a tow truck."
The trucking company behind the metal spill apologised and pledged to foot the bill for impacted drivers
"We're very sorry for all the concern," Daniel Falconer of NJ Ashton Group told 2GB.
"Thank God that no one's had a major accident or anything."
Drivers of B-double trucks were advised to park up until the motorway reopens.
Other drivers are advised to use the old Pacific Highway instead.
