Greater Anglia guards who are members of the Rail Maritime and Transport Union are to hold another one-day strike today (Saturday) over their role.
The train operator insists the action will not affect passengers – it has trained other staff to take on their roles.
But RMT general secretary Mick Cash said: 'The vital safety role of guards is still under threat and the extension of driver only operation remains a serious risk.'
A picket line will be in place at Norwich Railway Station, amongst others across the region.
The union agreed to one-person operation of about 60pc of GA trains several years ago.
Jamie Burles, Greater Anglia managing director, said: 'We are very disappointed that the RMT has announced a strike.
'Our position remains the same: we highly value our conductors, we're keeping them on our trains, but we want them to concentrate on customer service rather than opening and closing doors. We will continue to attempt to talk to the RMT to try to find an acceptable solution.'
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