Survivors, relatives and members of the emergency services are expected to gather at the memorial to the tragedy which claimed 35 lives and injured 500.
Three trains from Basingstoke, Poole and Haslemere were involved in the crash caused by faulty wiring, one of the worst train crashes of recent times.
Ninety-three safety recommendations were made following the tragedy. There will be a small prayer service at 8.30am for family and close friends only, and a larger remembrance service at 10.30am. The service is open to the public at the memorial garden by Spencer Park.
Because of this, there are delays of up to 30 minutes between London Waterloo and Clapham Junction. These delays are expected to continue until approximately 18:30.
To find out whether this will impact your journey and to get alternative options planned for you, please use the National Rail Enquiries real-time Journey Planner, or call TrainTracker on 0871 200 49 50.
Further signalling problems caused delays to services between Havant in Hampshire and Chichester in West Sussex, between Shrewsbury and Wolverhampton and between Yeovil Junction and Salisbury in the West Country.
Another signalling problem, at Wandsworth Common in south-west London, led to delays to services through Balham station in south-east London, while illness to a passenger resulted in delays to services between Shenfield in Essex and London's Liverpool Street station.
No trains were able to run in and out of Moorgate station in London due to a lineside fire in north London. There were also delays in and out of another major London terminus - Waterloo - due to a signalling problem at Clapham Junction in south London.