An unlimited number of 24-hour tram stoppages tops the list of disruptive measures the union has threatened to take against Yarra Trams, as talks on a new enterprise bargaining agreement turn hostile.

The union seeks an 18 per cent pay rise over three years, and has written to all members stating that Yarra Trams has offered a rise of just 1.33 per cent a year unless its staff agree to a string of productivity gains.

Phil Altieri, secretary of the tram and bus division of the Rail Tram and Bus Union, said Yarra Trams was already reaping the benefit of productivity gains from its staff, who had helped bring down fare evasion to record lows this year and improve on-time running to its best levels since the operator took over the system in 2009.

The union applied to the Fair Work Commission late on Thursday for the right to vote on 10 forms of protected industrial action.

Along with an unlimited number of 24-hour tram strikes, which would virtually paralyse Melbourne's inner-city transport network, the list of potential actions includes:

• bans on issuing infringement notices and on-the-spot penalties by authorised officers, and "free travel days" for the public as inspectors refuse to check myki cards;
   
• bans on short shunting, where trams terminate part-way along a line in breach of the timetable; 
   
• bans on tram drivers making announcements;
   
• overtime bans;
   
• bans on wearing uniforms;
   
• an unlimited number of four-hour work stoppages.

Mr Altieri said the union had been bargaining in good faith since April 22 but was still "miles apart" from the company. The current enterprise agreement expired on June 30 but stays in effect until a new deal is struck.

In a newsletter issued to all members, the union accused Yarra Trams of being "greedy" and demonstrating a lack of respect for staff.

"We will do our best not to disrupt the travelling public but we won't put up with Yarra Trams undermining workers' conditions when it's the same workers who've made it a successful business," Mr Altieri said.

Yarra Trams spokesman Simon Murphy said the union's application to Fair Work was a standard negotiating tactic designed to improve its bargaining position.

"We remain committed to reaching an agreement that is fair to all parties and is reached in a productive manner, without disrupting the public through industrial action and allows us to continue improving tram services in Melbourne," Mr Murphy said.

Negotiations between Victoria's Rail, Tram and Bus Union and Melbourne's transport operators, Metro and Yarra Trams, threaten to become an industrial relations headache for the Andrews government.

Metro is also locked in negotiations with the union over a new workplace agreement, and the union got permission from the Fair Work Commission on Thursday to hold a postal ballot on taking industrial action.

Proposed industrial action by Metro staff that would affect metropolitan rail services include work stoppages, bans on myki checks and bans on station skipping and train cancellations.

Luba Grigorovitch, the union's Victorian branch secretary, said in a statement that Metro staff were anxious for a new agreement to be signed. It is also pushing for an 18 per cent wage rise over three years.

"Our current agreement expired last week and after three months of negotiations, with little sign of progress, our members have had enough," Ms Grigorovitch said.

The conflict between Yarra Trams and the union comes at a time when the tram system is under increased pressure due to soaring patronage. Trams are the fastest-growing transport mode in Melbourne, with patronage rising more than 10 per cent in the 12 months to March, according to Public Transport Victoria.

The huge jump was mostly attributed to the introduction of the free tram zone in the CBD and Docklands.

Patronage in the free tram zone has boomed 22.6 per cent, and packed trams have become a common sight at all times of the day in the city centre.

Meanwhile, fare evasion on trams fell to a record low 4.8 per cent in May, Public Transport Victoria says.

Melbourne's last tram strike happened in 1997, just in time for the second Formula One grand prix.