HEAVY rainfall and flooding is causing travel chaos on the Brighton Main Line.

Cancellations and delays of more than an hour are affecting journeys travelling through Haywards Heath - to and from Three Bridges, Brighton and Lewes.

Disruption was initially expected to last until 12pm, but this has since been extended to 4pm.

The incident is also expected to have a " severe knock on effect to services between Brighton and Bedford, Sutton and St Albans, Horsham and Peterborough".

A Southern Rail spokesman said: “Due to the heavy rainfall in the early hours of this morning, water levels were above the railheads which meant that train services could not run past Haywards Heath until the water levels reduced.

“Network Rail Engineers arrived to site at 6.09am and examined the lines.

“At this point a decision was made to allow train services to run through but at reduced speed of 5mph as the water levels had reduced enough to allow movement through.

“Network Rail’s quick response team will remain on site and carry out further inspections and use water pumps where necessary.

“When the water level rises above the rails, trains have to reduce their speed to prevent damage to the train.

“If the track has a live conductor rail, flooding can cause a short circuit and cut power to the trains and track side equipment.

“Heavy rain can also overwhelm the drainage systems, flooding tracks and slowing down trains in the vicinity, causing delays to your journey.

"Particularly on busy routes, where trains need to run to a very tight schedule, such incidents can cause knock-on delays that continue for hours afterwards.

"These knock-on delays often affect both the route with the issue and any connecting routes.

"This, in turn, can mean that trains, drivers and crews aren't in the right place at the right time to run other services in the day's timetable.

"In order to bring the services back to normal, we will be forced to alter some of the services. We expect the service alterations and delays to continue until 2pm."

The spokesman also warned that “Southern, Thameslink and Gatwick Express services will be exceptionally busier than usual during this time”.

He added: “Tickets will be honoured across all Southern, Thameslink and Gatwick Express routes during this time.

“In addition to this, you can also use your ticket with the following existing bus routes:

“Metrobus on routes 271, 272, and 273 between Crawley, Three Bridges, Haywards Heath, Wivelsfield, Burgess Hill and Brighton.

“Brighton and Hove Buses on route 29 between Lewes and Uckfield.”

At about 2pm, the spokesman said all lines through the station had been reopebned, but there were still delays on the line.