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.
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The latest weather for the east with Philippa
The latest weather for the west with Philippa
Met Office issues storm warnings overnight as 80mph winds are expected across the south and east. Storm Imogen is due at around 3am