West Sussex County Council is planning to make vital repairs to the A24 Broadwater Bridge in September.
The bridge, which crosses the West Coastway rail line, is a key route in and out of the town centre.
It is now over 40 years old and a regular safety inspection revealed water is leaking through the bridge deck, causing small pieces of concrete to loosen and fall.
If repairs are not carried out soon the County Council would be forced to shut the bridge completely. By starting work in September it means the bridge will remain open – although traffic travelling north along the A24 will be prohibited from turning right into King Edward Avenue for the duration of the works.
County Council Cabinet Member for Highways and Transport, Pieter Montyn, said: “By taking this action now, we are shortening the length of time it will disrupt the general public.
“We need to make the bridge safe – and doing it this way means we don’t have to close it off completely.
“We apologise for the inconvenience and politely ask motorists to find alternative routes while this work is taking place.”
The repairs should finish by late November.