Highways engineers are working with emergency services to get the A24 re-opened in the Dial Post area following a major diesel spillage from a lorry.
The spillage covers nearly a mile-and-a-half of road, including both north and southbound carriageways, and thousands of square metres will have to be resurfaced.
A refrigeration trailer became detached from an articulated lorry heading north, just past the Dial Post junction, overnight Sunday/Monday. The container overturned on the central reservation and partially across a lane.
During the accident, the lorry’s fuel tank was damaged and the vehicle continued for about half-a-mile, leaking diesel, and then back on the southbound carriageway, leaking a continuous spill 0.9miles, before stopping at the Dial Post junction.
There was also diesel across the north and south carriageway at both points where the lorry turned around.
A West Sussex Highways spokesperson said: "We will have to resurface a total of 3,000 square metres of the north and southbound carriageways.
“We had hoped to re-open the road in time for the start of rush-hour traffic but this has not been possible due to the nature of the vehicle recovery involved.
“We cannot be specific, but we are aiming to re-open the road as soon as possible tonight – the southbound will be first, with the northbound following sometime after that.
“Meanwhile, we would ask road users to please avoid the area.
“We realise this has caused a major disruption for road users and would like to thank them for their patience and understanding.”