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Motorcyclists are calling for wire median barriers to be removed immediately from motorways and state highways after the gruesome death of a young Auckland rider at the weekend.

Daniel Luke Evans, 21, was killed after hitting a wire barrier - nicknamed a "cheese-cutter" by motorcyclists - on the Southern Motorway near Papakura about 3.30am on Saturday.

His death has sparked messages of outrage and sorrow on an internet motorcyclists' forum and spurred calls for Transit NZ to abandon plans to extend the barriers and for it to dismantle those already in place.

A motorcycling friend of the dead man, Felix Tsang, said on 3 News last night that Mr Evans was following him when thrown from his machine and into the barrier.

"I stopped and raced back to the scene where it first happened and find that he has been severed, waist down, and was lying on the road - it was extremely disturbing," Mr Tsang said.

"With the cheese-cutter ... he had no chance."

Contributors to the Kiwibiker internet forum accused Transit of considering only cars and trucks when installing the barriers and ignoring "an unacceptable risk to motorcyclists", a claim denied by the highways agency. Some suggested a protest blockade of the motorway to force the removal of the barriers.

Motorcycling safety consultant Allan Kirk told the Herald that although there might be some stretches of road where wire could be justified because of limited space, notably the narrow coastal highway north of Wellington, it was "utterly unforgivable" of Transit to install these where there was enough room for steel barriers.

Veteran Auckland motorcyclist Lou Girardin, a former Ministry of Transport patrolman, said he did not believe the wire barriers were acceptable anywhere and suspected Transit was driven by cost considerations. "If you set out to design something to mutilate the human body, you couldn't do any better.

"It's not a matter of speed - if you're tipped off [a motorcycle] by a driver changing lanes you are dead or at the very least your limbs will be severed. These things are just horrendously dangerous."

But Transit's national operations manager, Dave Bates, denied there was much difference in cost between wire and steel barriers and said the main reason for using wire was its greater effectiveness in protecting most road users.

He could recall no previous deaths of motorcyclists hitting wire barriers and did not believe they would have much more of a chance against traditional W-section steel guard-rails.

Asked whether Transit might now review plans to extend the barriers, Mr Bates said it investigated every fatal crash on its network "to see whether there is in fact anything we can do".