Canterbury and West Coast mayors have joined the fight against new snow road rules

Almost 20-thousand people have signed the petition to stop NZTA switching from snow chains to an open/close system in Arthur's and Porters passes.

Now Greymouth, Westland, and Selwyn District's mayors have written to ask the Transport Minister to intervene.

Westland Mayor Bruce Smith says the road closures are disruptive and make no sense.

He says just recently they closed Arthur's Pass for 16 hours - and when trucks were finally allowed through there was barely enough snow to fill a cup.