Trains between London's Paddington station and Reading are being disrupted because of a fire close to the line.
Toby Hindson took this picture of the fire on Sunday
A 200m exclusion zone has been put in place around the plastics factory in St Mary's Road, Langley near Slough, while gas cylinders at the site are cooled.
Several explosions were heard in the area but the fire is now under control.
First Great Western said two of the four lines affected in Berkshire have reopened, but delays to rail services may continue into Monday.
Police and fire crews remain at the scene of the fire in Deseronto Wharf, which began just before 1100 BST on Sunday.
Thames Valley Police said no-one had been injured in the blaze.
A Network Rail spokeswoman said: "Normally when gas cylinders are involved a cordon will stay in place for 24 hours so the line will probably be affected until midday on Monday.
"The gas cylinders can explode and have been exploding at the site.
"Some of the signalling in the area has been damaged and that will also need to be fixed."
She said the four rail lines were inside the 200m exclusion zone.
A spokesman from Berkshire fire service said: "There was a large quantity of waste material and plastic on fire.
"A series of explosions have been witnessed at the scene."