There was gridlock around Arundel, Littlehampton and Wick this morning as huge tailbacks formed after a motorcyclist hit a car on the A27, at Crossbush, at 10.20am.
The eastbound carriageway of the road was closed for several hours, while a crew from the Sussex Air Ambulance landed to treat the injured rider.
A spokesman for Sussex Police said motorcyclist suffered serious chest injuries.
The force has since appeared for witnesses to the collision to contact them by emailing [email protected] or by calling 101 quoting serial number 399 of 13/5.
Elsewhere in the county, there was a similar crash near Bognor Regis, just hours before, involving a car and Honda motorcycle.
That collision took place at about 8.11am at Virginia Gardens, in Felpham, close to the junction of the A259 Flansham Lane.
A police spokesman added: “The motorcyclist was thrown from the machine and suffered potentially serious pelvic injuries.”
The road was closed for about two hours.