The closure, scheduled for between 8pm on Saturday, 30 June and noon on Sunday, 1 July, will see the 1400-tonne bridge at Junction 12 removed using hydraulic breakers: This is the same technique used to demolish the Catthorpe viaduct at J19 of the M1 in January this year.
The M1 will be closed in both directions between Junctions 11 and 13.
Northbound traffic will be encouraged to leave the M1 at Junction 9 to prevent the A5/A505 junction in Dunstable becoming congested. Road users will be diverted from Junction 9 along the A5 through Dunstable and Milton Keynes, where it will join the A509 Portway and re-join the M1 at Junction 14. The diversion is expected to add 25 minutes to journey times. Yeah right! 
Southbound traffic will be diverted from Junction 13 along the A421 to the A1, down the A1/A1(M ) to the M25 and either continue its journey or go back up the M1 to Luton. People should allow up to an hour for this diversion Yeah right again.