Track engineers carried out a safety inspection on the line 24 hours before a train derailed and injured more than 20 people.
Three carriages of a Southern Rail service from London Victoria to Eastbourne came off the track just before 4pm on Thursday, August 13 close to Lewes station.
The cause of the crash on the line between Lewes and Haywards Heath has not yet been established.
Train company Southern said in an X post on Wednesday evening that a safety inspection of the track was taking place between Lewes and Haywards Heath.
Just under 24 hours later, Southern said on X a train had derailed ‘in the area between Haywards Heath and Lewes.’
It has not been confirmed whether the section of track inspected on Wednesday was the same piece of railway where Thursday’s derailment happened.
Images from above the scene appeared to show parts of the track that had buckled.
A local resident at the scene said he had seen a long and heavy freight train pass through the same section of track earlier in the day.
Speaking at the scene, a local resident called Mike described seeing a large freight train pass over the same section of track today.
He said: ‘I was going fishing this morning. I crossed over the track on a bridge, when a cargo train went through with about 20 carriages on it.
‘It must have had 20 tons on each carriage. That’s not going to do the railway line any good is it?’