Rail passengers have been warned to expect disruption to services between Wakefield Westgate and Sheffield this morning.
National Rail Enquiries said that passengers should expect trains to be diverted, cancelled or delayed by up to 30 minutes.
A fault with the signalling system between Wakefield Westgate and Sheffield/Doncaster has been blamed for the disruption.
The disruption is expected to continue until 11am today (Wednesday), and mostly affects services from Wakefield Westgate towards Doncaster/Sheffield.
CrossCountry routes between Edinburgh and Plymouth, and between Glasgow Central and Birmingham New Street will be affected, as well as Londern North Eastern Railway services between Skipton, Harrogate, Leeds and London Kings Cross.
Northern services between Leeds and Doncaster / Sheffield, and between Leeds and Knottingley will also be affected.