Workers on the Glasgow Subway * will stage a strike over three * consecutive days on the same weekend the city stages Scotland's biggest music festival.
Unite held three * days of action last week but the latest wave will coincide with TRNSMT on Glasgow Green.
The strikes are due to a dispute between Unite the union and subway * operator Strathclyde Partnership for Transport (SPT) over working conditions.
The union has claimed the underground is badly understaffed, an accusation SPT has rejected.
Unite said more than 100 workers will go on strike on Friday 11 July, Saturday 12 July and Sunday 13 July.
More than 50,000 music fans will attend TRNSMT – which is being held half a mile from the St Enoch subway * station – on each of the strike days.
Headliners this year include Snow Patrol, Biffy Clyro and 50 Cent.
The union's general secretary Sharon Graham said: “Unite's members will no longer accept intolerable working conditions.
“SPT has had years to resolve the problem and has failed to do so. Our members have said enough is enough.
“We will support them all the way in their fight for better jobs, pay and conditions.”
The union has had a continuous overtime ban in place since 13 June and an interim offer by SPT was “overwhelmingly rejected” by its members.
BBC Scotland News has asked SPT for comment.
The operator previously said it remained “committed to seeking a resolution through positive ongoing negotiations”.
A social media post during last week said that season ticket holders affected by the strikes will receive one day of pay-as-you-go credit on their smartcard per affected day.
Last month's strikes coincide with three * major gigs at Bellahouston Park, which concert goers often reach via walking from the subway * station at Ibrox.
Singer-songwriter Sting headlined at the park on Wednesday, while rock bands Simple Minds and Stereophonics took to the stage on Friday and Saturday.
