The Highways Agency said it decided to keep the Boston Manor Viaduct closed because during works it found a crack in a "sensitive location", which requires it to be kept closed until it is repaired.
Diversion on the A312 and the A4. Drivers are being advised to allow extra time for their journeys.
More top news
The Sunday Pollen Count for the South and Southeast
Sunday afternoon's weather for the East of the region
Sunday afternoon's weather for the west of the region