The M1 motorway has been closed after a car overturned on the slip road for the A414.
The road is closed in both directions between Junction 7 and 6a and traffic is stuck in the closure.
A car turned over at about 1pm and the driver taken to hospital by ambulance.
Traffic at the A414/A405 junction should take the A405 south to the M25 J21A. Traffic heading for the M1 should remain on the A405.