Mr Butson says the union has heard of possible moves towards mothballing the Napier line, following downturns in tonnage brought about by the loss of the Oringi-Hawera "milk trains" amid the commissioning of Fonterra's new $235 million powder plant at Pahiatua and of other freight no longer heading to Napier Port.
The union's concerns are heightened by moves to allow higher, longer and wider trucks on the roads, which would further harm the viability of the railway network.
"We are of the view that this is not good enough and our national railway network should be improved," Mr Butson said. "It beggars belief that in a modern 21st century developed economy we have a railway system that is funded in a manner that loads cost on the operator whilst the trucking industry does not pay the price for the environmental damage and congestion it causes.
"A forward-thinking government would be investing in rail for the 21st century and beyond rather than considering increasing the size and number of diesel-belching dinosaurs like trucks," he said.
Meanwhile, KiwiRail is still evaluating proposals submitted regarding the Napier-Gisborne tender.
"Normally our procurement processes would have allowed us to have reached an outcome by now," the company spokesman said. "However in this case, both the situation and the submitted proposals are unique and warrant taking extra time to get the right decision."
As part of this process, KiwiRail is continuing to work with Hawke's Bay Regional Council and "one other party".
The spokesman said the nature of those discussions remains confidential but a decision is expected "in the coming months".
Napier MP Stuart Nash is about to ask questions, and says: "As I have argued for the last few years regarding the Napier-Gisborne rail link, an integrated transport infrastructure is vital if we are to attract the sort of economic development we need in the Bay. This means road and rail, not one or the other.
"Letting our rail infrastructure fail is such a short-sighted approach and incredibly frustrating, especially when the government is talking about spending close to $2 billion in Auckland on a rail loop."
Mr Nash said the wealth created in the regions is "incredibly important" to the economic health and well-being of the country.
"Why we are being ignored is beyond me."