A 23-year-old man from Batley is in a critical condition after he crashed his motorbike on the M621.
The man was travelling from Leeds on his blue Kawasaki Ninja motorbike, and was on the entry slip road to junction four of the motorway when he crashed into the central reservation.
The incident happened at around 3.20pm on Wednesday.
Police say he was taken to hospital where his condition is still critical.
Anyone witnesses to the collision is asked to contact PC Michael Auty on 0845 6060606.