‘Improvement’ work to the A259 Comet Corner junction is now set to take twice as long as originally planned.
It was due to take eight weeks from January 9 but will now run until the end of April.
A spokesman for West Sussex County Council said: “The delay was caused by a Portsmouth water main supply which was uncovered at an exact depth to interfere with our drainage plan.
“We have had to arrange with the utility company to divert the main, hence the delay.
“The works will continue to the end of April.”
The scheme, which was originally estimated to ‘cost about £550,000 in total’, made up of the highway improvements at £375,000, funded by developers’ contributions and £175,000 by the county council for drainage works.
The project involves: widening the bend in Worms Lane; extending deceleration lane exiting the A259 into Worms Lane; upgrading drainage ditches; installing new drainage pipes; removing vegetation to improve visibility; and widening existing crossing to make it safer for cyclists, pedestrians and mobility scooters.
The spokesman added that the delay has provided an ‘opportunity’ for the council to ‘complete some additional works for the A259 Littlehampton to Bognor shared cycle route’.
He said: “This has caused a small delay – however the work done now will save much time later on when the remainder of that project is done.”
The work was initially designed to ‘complement’ the new path which has a completion date of ‘next year’.