Two-way signals are in place on Brighton Road for ‘utility repair and maintenance works’, according to one.network, which added that delays are ‘likely’.
Southern Water is responsible for the works, which were approved by West Sussex County Council.
The water company said this work is to connect two water mains at the A259 and ‘should be finished tomorrow’ (Wednesday, September 18).
A spokesperson for Southern Water said on Tuesday: “Our teams are connecting two water mains at the A259 in West Sussex.
“We’re sorry for the disruption this is causing customers, commuters and businesses, we aim to finish this work by tomorrow afternoon.”
The work means there is two way traffic control ongoing on the A259.
The temporary traffic lights were operational by 8am on Monday and will be in place until 11.59pm on Wednesday.
Sussex photographer Eddie Mitchell posted a picture of a long queue of traffic.