The A23 carriage way has now reopened in both directions following flooding.
At 9.45am, the northbound carriage of the A23 opened followed an hour later by the southbound carriage.
Southern have just announced at 10.15am that the line at Balcombe is now open and trains are running between Brighton and London again.
The A23 had been closed in both directions between the M23 at Pease Pottage and the A272 turn-off at Bolney due to flooding.
Trains between Haywards Heath and Three Bridges had been cancelled since 6.30am because of flooding.
Suusex Police are now advising motorists to consider whether they really need to make a car journey before setting out today.
The road was closed at just before 5am this morning after an inch and a half of rain fell overnight.
Specialist equipment called gully suckers arrived at the scene at just before 7am and are currently clearing away the standing water.
Not time has been given yet for a scheduled reopening.
Diversions routes are currently in place with northbound traffic exiting the A23 northbound at the junction with the A272 and travel westbound to join the A24 northbound and travel to join the A264 eastbound following signs to join the M23 at J11.
Southbound traffic are being redirecvted from the M23 at J11 to join the A264 travelling westbound to join the A24 southbound and then join the A272 eastbound to join the A23 soutbound.
Tailbacks coming out of Brighton are stretching back about five miles with delays of at least an hour and a half.
Rail services between Haywards Heath and Three Bridges are cancelled in both directions due to flooding in the Balcombe tunnel.
Replacement buses are being affected by flooding on local roads, so passengers for London are advised to travel via Barnham and the Arun Valley, or via Hastings for Southeastern services.
Southern tickets are being accepted on Southeastern and First Capital Connect services.
The rail operator are also reporting that no trains are running between Hurst Green and East Grinsteads because of flooding at Lingfield.
The roads between the two are also flooded which means no rail replacement buses can operate either.
Flooding is also being reported across Crawley while the A24 also has flooding at Findon, Broadbridge Heath and Kingsfold.
Mark Hallett, duty operations manager for the Highways Agency in the South East, said everything was being done to drain the water and reopen the road as soon as it was safe to do so.
He said: “This is a the main route between Brighton and London and obviously is heavily used.
"We have equipment on its way and will attempt to drain the water and reopen the road in both directions as soon as it is safe, but safety has to be our main priority.”
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