Coal train drivers at the centre of a 48-hour rail stoppage say the dispute is about their right to be represented by a union.
Rail Tram and Bus Union (RTBU) national secretary Bob Nanva says the stoppage is about the right of rail freight workers to collectively bargain through their union.
"Pacific National has tried to frustrate the legitimate right of this workforce to collectively bargain," Mr Nanva said in a statement.
"The company's recent behaviour has now made today's strike as much about our right to stand up for ourselves as it is about this particular EBA (enterprise bargaining agreement).
"Through the course of this dispute Pacific National has offered inducements to employees who don't take part in industrial action and threatened a lower pay offer for those who do," he said.
RTBU members employed by Pacific National Coal, a division of the stock exchange listed company Asciano, began their 48-hour strike at midnight.
The RTBU and Pacific National Coal could not agree on Thursday on a new enterprise agreement for 800 workers, despite the involvement of the Fair Work Commission and discussions with Workplace Relations Minister Bill Shorten.
The strike threatens the delivery of 600,000 tonnes of coal worth more than $55 million at current prices by Pacific National, while disrupting the 20 to 30 per cent of the state's coal it does not haul because of about 40 idle trains blocking lines.
The RTBU started negotiations last year by asking for pay rises over three years of nine, seven and seven per cent.
Pacific National responded with four per cent a year for three years.
The workers rejected the offer but Pacific National reduced its offer to three per cent from this week, which led to an escalation of the proposed strike action from 24 hours to 48 hours.
AAP understands the union has reduced its claim to seven, five and five per cent.
Most of the workers, which include train drivers, maintainers and terminal operators, are paid a base rate of $63,000 a year, but the company says the average fully trained train driver actually earns $105,000 including overtime.