In West Sussex, severe delays have been reported on Crockhurst Hill eastbound between A27 Arundel Road and A27 Sompting Bypass.
Delays are also increasing on A259 New Road westbound between A259 and B2140 Station Road, as well as on A27 Old Shoreham Road eastbound between Church Lane and Hoe Court.
There is queueing traffic on A27 Lyminster Road westbound at A284 (Crossbush Junction).
In Chichester, there is queueing traffic on A27 eastbound before A259 Cathedral Way (Fishbourne roundabout) and before the A259 (Bognor Bridge roundabout).
Towards Horsham, delays are also said to be increasing on A24 London Road northbound between A24 and Rock Road. There is increasing queuing traffic on A264 eastbound between A24 (Great Daux Roundabout) and B2195 Crawley Road (Moorhead roundabout).
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Meanwhile, in East Sussex, delays are increasing on A27 westbound between A23 London Road and A293 (Portslade / West Hove turn off).
Severe delays have been reported on B2123 Falmer Road southbound between A27 Falmer Hill (Falmer / Rottingdean Junction) and Crescent Drive South.
Traffic is also slow on A22 Hailsham Bypass at A271 Lower Horsebridge (Boship roundabout).
Earlier this morning, shortly after 5am, there was a police incident on the trainline at Brighton.
Southern Rail said some trains from Brighton towards Hove were being delayed, whilst police were at the scene.
British Transport Police said officers were called to Brighton station at 5.06am this morning, following 'reports of a man causing a disturbance on a train'.
"Officers attended, however no further action needed to be taken," a spokesperson added.