A further 40,000 UK rail workers will join another national strike planned for later this month as unions ramp up a dispute over pay and proposed reforms to the network.

The National Union of Rail, Maritime and Transport Workers said staff will stage walkouts at 14 train companies on Sept. 15 and 17.

They will join train drivers from the Aslef labor group, which on Wednesday announced a strike on Sept. 15 which includes the London Overground.

RMT General Secretary Mick Lynch said his “industrial campaign will continue for as long as it takes.”

Workers are demanding steeper pay hikes after UK inflation climbed into double-digits. Some analysts have predicted that inflation could hit 22% next year.

Another union, the Transport Salaried Staffs’ Association, has announced a 24-hour rail strike starting at midday on Sept. 26.

Rail workers have staged several walkouts through the summer over pay and what the unions describe as an attempt to erode employment terms and conditions. The government and train operators say that reform is crucial in light of changing passenger habits following the Covid-19 pandemic.