Rail travellers are facing the first of six consecutive Saturdays of reduced services.
Only five Northern trains will run in either direction between Sunderland and Hartlepool on August 25 along the Newcastle-Middlesbrough Durham coast route.
The Rail, Maritime and Transport Workers (RMT) union earlier this week confirmed that similar action will also be held on all five Saturdays in September.
The union, which had already scheduled strikes for September 1 and 8, has now earmarked September 15, 22 and 29 for disruption as the bitter dispute over staff and passenger safety escalates.
Other stations along the Newcastle-Middlesbrough route to be affected include Billingham, Seaton Carew and Seaham.
The first trains north on Saturday will leave Hartlepool and Sunderland at 7.30am and 7.56am respectively with the last services departing at 6.04pm and 6.29pm.
The first trains south will leave Sunderland and Hartlepool at 8.01am and 8.25am respectively with the last services departing at 4.03pm and 4.28pm.
Metro and Grand Central trains using the same lines are not affected by Saturday's action.
The RMT union fears that ongoing modernisation programme by Arriva Rail North, Northern's parent company, is partly a cover for threatening the long-term role of guards by introducing more driver-only trains.
It claims passenger and staff safety will be compromised "in the name of increased profits" and that 8,000 jobs nationwide are threatened.
RMT general secretary Mick Cash accused Northern's owners, Arriva Rail North, from pulling back from meaningful talks and added: “German-owned Northern Rail want to run nearly half a million trains a year without a safety critical guard on board in a move that would wreck both safety and access to services and they should listen to their front-line staff and pull back from that plan immediately."
Yet Richard Allan, deputy managing director at Northern, questioned why more strikes had been called only a week after the union had agreed to talks with mediation service ACAS.
He added: “We’re trying to fix this dispute. Since the RMT agreed to reconvene the joint steering committee meetings and ACAS mediated talks, we are in the midst of arranging dates to meet.
"We have again urged the union to suspend any planned strikes. Instead, they have chosen to strike on every Saturday in September.”
The company insists the improvements package as a whole will lead to updated trains with better stations, faster journeys and a greater staff presence.
The guards's jobs will also be protected until the end of Northern's existing franchise in 2025.
Added disruption caused by engineering work means that only around 30 per cent of its services across the north of England will run on Saturday.
Full details of the emergency timetable can be found at www.northernrailway.co.uk/strike.
Further information is also available by contacting 0800 200 6060