A fault with the signalling system in the Twyford area means that some lines are blocked.
Trains between Slough and Reading may be cancelled or delayed by up to 50 minutes as a result.
Disruption is expected until 06:00.
Check before you travel:
You can check your journey using the National Rail Enquiries real-time Journey Planner.
Compensation:
You may be entitled to compensation if you experience a delay in completing your journey today. Please keep your train ticket and make a note of your journey, as both will be required to support any claim.