Serious collision investigation officers are appealing for witnesses to a collision on the A229 Bluebell Hill near Maidstone.
The incident took place at around 2pm on Tuesday 21 May 2019 on the slip road for Aylesford from the Maidstone-bound carriageway and involved a black Yamaha motorcycle which collided with a chalk bank.
The motorcyclist, a 19-year-old man from the Maidstone area, was taken to a London hospital by air ambulance where he remains in a serious condition.
Officers are working to establish the circumstances of the collision and are urging anyone who saw the motorcycle in the moments leading up to the collision, or who have dash cam footage from the area around the time, to contact them.
Witnesses or those with dash cam footage should call the appeal line on 01622 798 538 quoting SM/DJ/58/19.