Queueing traffic has been reported on A27 eastbound in Chichester, before A259 Cathedral Way (Fishbourne Roundabout).
'Severe delays' are also said to be increasing on A27 eastbound between A27 (Emsworth Services) and A259 Cathedral Way (Fishbourne Roundabout).
There are also queues on A27 Chichester Bypass before A286 Stockbridge Road (Stockbridge Roundabout).
Elsewhere in West Sussex, there are delays on A259 New Road westbound between A259 and B2140 Station Road.
There is also slow traffic on A27 in Worthing, whilst delays are increasing on Crockhurst Hill eastbound between A27 Arundel Road and A27.
In East Sussex, a stalled vehicle is causing delays on A27 eastbound. The A293 is partially blocked at the Portslade / West Hove turn off.
This adds to already 'severe' delays in the county, with temporary lights causing traffic chaos on A259 Brighton Road in Newhaven.
The roadworks, near the one way system, are reportedly causing journey times of almost an hour.
Heavy delays are increasing eastbound between Central Avenue and Church Hill.
Meanwhile, there are queues on A27 eastbound at the Hangleton link junction in Hove
There is also slow traffic on B2123 Falmer Road both ways before Warren Road.
Delays are reportedly increasing on A259 Marine Drive westbound between Ambleside Avenue and Newlands Road.