Passengers are being warned of delays and disruption to services on the cross city line to and from Lichfield.
A signalling fault at Sutton Coldfield is being blamed for the issue which will continue until at least 9.15am.
West Midlands Railway says road transport has been ordered to run between Blake Street and Lichfield Trent Valley, while ticket acceptance are also running on National Express West Midlands buses 14, 65, 67, X3, X4, X5 and X14 into Birmingham.
Due to a fault with the signalling system between Birmingham New Street and Lichfield Trent Valley trains have to run at reduced speed on all lines, Road transport has been ordered to operate between :-Lichfield Trent Valley-Lichfield City, Lichfield City-Blake Street.
— West Midlands Railway (@WestMidRailway) May 1, 2018