The A27 eastbound from Portfield Roundabout to Tangmere is still flooded and remains closed.
After more heavy rain the road continues to be impassable.
The road has nearly been closed for a week.
A local diversion is in place, however, a Highways Agency spokesman said HGVs should use the A259, Bognor Road.
It is likely to remain closed for the rest of the day.