North East rail travellers are being urged to check ahead as engineering works are carried out over the next five weekends.
Grand Central services between London and Sunderland will be diverted via Durham on Sunday, extending journey times by up to 30 minutes, while replacement bus services will run between Eaglescliffe and Hartlepool.
The work will see Network Rail engineers moving control of the signalling from Bowesfield signal box to the rail operating centre in York, upgrading Urlay Nook level crossing and improving track in the area.
The first phase of the work will take place on Sunday, February 24, and Network Rail is advising passengers to plan their journeys and check with National Rail Enquiries or with their train operator before travelling.
The work will mean changes to train services as coach replacement services and diversionary routes will be in place.
TransPennine Express services between Manchester Airport/Piccadilly and Middlesbrough will be diverted to run to/from Darlington and buses will replace services between Northallerton and Middlesbrough.
The upgrade to signalling follows on from the completion of similar schemes in the North which have seen control of signalling from across East and West Yorkshire move from old-fashioned lineside signal boxes to the more modern, state-of-the-art rail operating centre, which brings greater reliability to the railway.
The projects will also impact on services on Saturday and Sunday, March 2 and 3, 9 and 10, 16 and 17, and 23 and 24.
Network Rail Route Managing Director Rob McIntosh, said: "We apologise to passengers who will be inconvenienced for a total of five weekends whilst we undertake this vital £3.5 million signalling and track enhancement project in the North East. We appreciate there is never a good time to work on the railway and we are working closely with train operating companies to keep disruption to a minimum.
“The Great North Rail projects is bringing tangible benefits to customers across the North of England. The work carried out will create a more modern and reliable railway which will allow us to provide a better experience to the passengers and communities we serve. We thank passengers for their patience and look forward to them being able to enjoy an enhanced service going forward."