Drivers are being warned about motorway closures as a 14-week roadworks programme kicks off next week.
National Highways says overnight work will be taking place between junction 8 for Hemel Hempstead and 9 for Redbourn from Monday June 27 until September 30.
All planned work will only take place on weeknights, between 10pm and 5am, but motorists will face diversions and possible delays.
The work to the motorway includes resurfacing, renewing markings, upgrading signs, and other general maintenance both on and near the carriageway.
From June 27 until July 30, the M1 will be shut northbound between junctions 8 and 9.
From August 1 until August 27, the M1 will be shut southbound between junctions 9 and 8.
Diversion signs will take motorway traffic via Redbourn and Hemel Hempstead.
From August 30 until September 17, the southbound exit slip road at junction 9 will be closed.
Then, from September 19-30, the A414 will be shut from the Park Street roundabout in St Albans towards junction 8 for the M1.
Once again, diversion signs will be in place and local routes are likely to be heavier than usual.
All closures mentioned will only be in force on weeknights between 10pm and 5am.
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