Motorists will not be able to use Trinity Road for a further 10 days after holes were found under the road.
The road, which has been shut throughout the school summer holidays for sewage network upgrades, was supposed to reopen today (1 September).
Voids were discovered beneath the carriageway last week which need urgent repair.
Environment & Infrastructure says they have considered other options, but the work that needs to be done is in the middle of the road.
"We understand the inconvenience this may cause and sincerely apologise for the disruption. However, addressing these issues now is essential to prevent future roadworks and further closures.
"We are engaging with affected businesses in the area to provide support and minimise the impact of the extended works.
"Public safety remains our top priority, and we appreciate your patience and understanding as we complete these critical infrastructure upgrades."
A new completion date of 10 September has been set.
Details announced of free childcare for two and three year olds
18-year-olds to have access to Jersey social housing
CI ferry operators to work together to improve inter-islands travel
'Show up and play' football games to tackle festive loneliness
New website helps children and families navigate the digital world
More time in Jersey for French day-trippers
Rapist jailed more than two decades after his crime
Jersey Airport to see 20,000 passengers in the run up to Christmas
