Supertram workers in Sheffield will go ahead with strikes next week, which it is claimed will 'paralyse' the network, after rejecting the latest pay offer.
Drivers and conductors will walk out next Monday, July 9, and Thursday, July 12, with the 24-hour strikes due to begin at 1am each day.
A further 72-hour strike is planned for July 20-22, the weekend of the Tramlines festival, if the dispute is not resolved before then.
Stagecoach Supertram had tabled an improved pay package in a bid to avert industrial action after union members turned down the initial offer of a 26p-an-hour pay rise in each of the next two years.
But the new proposal, which bosses claimed equated to an hourly increase of 6.8 per cent for conductors and 5.8 per cent for drivers, taking into account the shorter working week proposed, was overwhelmingly rejected.
In the first ballot, Unite members voted 91 per cent for strike action and 95 per cent for industrial action short of a strike.
In a second ballot held yesterday, 69.7 per cent of members taking part voted against accepting the revised pay offer.
Unite said the revised offer still amounted to an 'insulting' pay increase of just 26p an hour when the details were analysed, and warned further strikes could follow if a better deal fails to materialise.
But Stagecoach said it was 'extremely disappointed' by the decision to reject an offer it said was higher than the average pay deal in the UK today.
Around 200 drivers and conductors are due to go on strike next Monday and Thursday.
Stagecoach said it would provide a replacement bus service between 7am and 7pm on those days, with a limited number of trams running within the same period.
A full timetable is set to be uploaded for passengers to view later today.
Unite regional officer Steve Clark said: "Our members have seen through the 'smoke and mirrors' conjured up by the management which amounts to a 26p an hour increase in the first year; 26p in the second year and potentially less than that in year three.
"In these inflationary times, our members want a decent pay rise, not one that borders on the insulting.
"We predict that the Sheffield Supertram system will be paralysed on the two days of strike action next week.
"We appreciate that this will cause inconvenience to the travelling Sheffield public, which we deeply regret. And as we understand the impact on the network, our door is open 24/7 for talks with the management to reach a fair settlement.
"However, unless the company comes up with a substantial cash offer for our hardworking members, more strike action during July is definitely on the cards."
Tim Bilby, Supertram's managing director, said: "We are extremely disappointed to see that union members are planning to strike on Monday. This decision will impact our customers the most leaving their travel options limited.
"However, passengers can be assured that we're doing everything we can in the circumstances by providing a replacement bus service between 7am and 7pm and a limited number of trams running within the same period.
"We have offered an effective increase in hourly rates over the first two years of 6.8 per cent for conductors and 5.8 per cent for drivers which incorporated, as suggested by the union, a reduction in the contracted weekly hours.
"This is higher than the average pay deal in the UK economy today. Any proposed strike action will only reduce the money available to employees for the pay deal."