The flooding at the junction of Southdown Road and Western Road, which occurred after heavy rainfall and often led to residents wading through water several inches deep, was first highlighted by resident Will Flewett in November, 2016.
The 64-year-old, of John Street, said the issue had been recurring on the road – a key route through the town – for at least 15 years without any authority taking responsibility.
During the winter, he said the conditions were ‘horrible’.
But Network Rail, which owns the land under the bridge, said solving the problem was not simple.
Investigations revealed that the water in Southdown Road drained into a ditch on railway land, squeezed in between the steep embankment carrying the railway and a listed flint wall, which had become clogged with silt over the years.
A spokesman said: “Previously, we would need to bring in cranes and close the road to clear the ditch, which was very complicated, disruptive and expensive.”
But Network Rail has now built a gate in the wall, which will allow access to clear the ditch and therefore prevent flooding.
As the wall was listed, planning permission had to be sought from Adur District Council to install the gate and drop the pavement kerb to allow easy, non-disruptive access.
The Network Rail spokesman said: “This has been a complex issue but we are pleased to have found a solution.”
Reacting to the news, Mr Flewett said finding a solution had taken ‘quite a while’ but said he was pleased the work had now been completed.
He said: “I’m looking forward to it being a nice thoroughfare that people can get down and not get drenched.
“It’s a nice looking gate and I’m pleased it got done.”