The A29 near Billingshurst is closed with slow traffic due to an accident involving a motorcylcle on Stane Street northbound between High Street and New Road, the AA said. It is closed for the second time to allow recovery work.
Southern Rail and Thameslink also warned this weekend trains to and from Brighton will be busier than usual.
A spokesman said: “Please allow extra time if travelling.
“Plan your journey. Wear a face covering in crowded spaces if you are not exempt. Be prepared to queue.”