The level crossing at the centre of a fatal crash in Barns Green will be closed for up to three weeks.
Barry Hearnshaw, 72, and his 15-year-old grandson Will Hallett died after a car and a train collided at the crossing in Emms Lane on Saturday morning (February 17).
Network Rail said both the crossing’s controls and the crossing itself were ‘severely damaged’ and it was working with West Sussex County Council to keep disruption to a minimum.
John Halsall, Network Rail’s South East route managing director, said: “We are all deeply shocked and saddened by this tragedy and our thoughts are with the family and friends of those who lost their lives.
“I know families, friends and our neighbours will want to know how this happened, and why, as soon as possible and we are working closely with the Rail Accident Investigation Branch to understand that.”
“We know how important this crossing is to local people and we’ll be working hard to get it open again once all the repairs are complete.”
A signed diversion route has been set up for road users.
Chandris Webb, Network Rail mobile incident officer, was at the scene on Saturday. He said: “We’re all incredibly grateful to everyone who went out of their way to help us on Saturday. This was so appreciated by everyone from Network Rail and the emergency services who attended this difficult incident.
“People brought us cups of tea and biscuits and provided welfare facilities. I know it might seem like a small thing, but it really made a difference on what was a very tough day for everyone involved.”