The lorry, which was travelling on the slip road towards the M27 westbound, left the carriageway and came to rest on land off Chestnut Avenue. A Hampshire Constabulary spokesman said: "Despite the best efforts of emergency services on scene, the driver, a man in his 20s, was pronounced deceased at the scene. The two left lanes leading to the M27 westbound slip road remain closed, while the two right lanes on the southbound carriageway are still open. A spokesperson for Hampshire Constabulary said: "Anyone with information should call 101 quoting reference 44260389435. "Alternatively, you can make a report online via How to tell us about an existing case or report | Hampshire and Isle of Wight Constabulary."