A trade union announced fresh strike action to coincide with the first anniversary of London’s Elizabeth Line, which connects Heathrow Airport and other suburban districts with the city center.

The TSSA labor group said dozens of members would walk out on May 24, a year after sections of the railway line finally opened following extensive delays and budget overruns. 

The union added that it would impose an overtime ban between May 27 and June 4 due to the row over pay. It argued that workers on the line are paid less than equivalent staff on the Tube and Docklands Light Railway.

It’s the second walkout on the line named after Queen Elizabeth II, Britain’s longest-serving monarch, who died in September. The TSSA first held a strike on the service on Jan. 12, resulting in the closure of the line through central London.

“Our members don’t want to have to take strike action, but they’ve had enough,” said Mel Taylor, an organizing director at the labor group.