Campaigners in Bradford District have welcomed trains with additional carriages but say the platforms at some stations will be too small.
The Northern rail company confirmed that six-carriage trains will be introduced to the Airedale and Wharfdale lines to ease overcrowding.
However, the Aire Valley Rail Users Group says that whilst the platforms at Keighley, Ilkley and Skipton stations will be able to accommodate them, those at other stops along the routes won't.
Northern said it is working with Network Rail to identify what work may be required.

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