Thousands of commuters were being offered replacement buses from Brighton to Preston Park after the “angle of the dangle” meant engineers struggled to move a train which came off the tracks yesterday afternoon.
Engineers worked through the night to try and get the train off the tracks, but technical problems meant they could not do it before trains started running this morning.
Train company Southern said that it did not expect the line to reopen until midday at the earliest.
The unofficial Brighton Station Twitter account explained: “For those asking (and those wondering) the reasons I have for not being mainline open this morning are problems in the night.
“The naughty train had to have the three rear carriages removed, but the angle of the dangle prevented this from happening in a timely manner.
“The initial lift was aborted due to problems involving the conductor rail height, The window was only a few hours, so was lost, sadly.”
Many commuters headed straight for Preston Park while some switched the start of their journey to Hove or travelled via Lewes.
Trains were still running along the east and west coastway lines.
Southern said: “Following a derailed train near Brighton station yesterday afternoon no trains will be able to operate between Brighton and Preston Park until at least midday.
“Services will start and terminate at Preston Park. Buses will shuttle between Brighton and Preston Park.
“Customers for London are advised to travel via Lewes or Hove while more buses are sourced.
“Buses will also be provided at Three Bridges and Haywards Heath.
“Southern and Thameslink will accept each other’s ticket holders.”
