The M25 will be closed in both directions between junction 25 (A10/Enfield) and junction 27 (M11) overnight, between 10pm and 6am, on Saturday 16 May.
Both carriageways will be closed in order to carry out routine testing on systems and equipment in the Bell Common Tunnel near Epping and the Holmesdale Tunnel near Enfield.
Clearly signed diversions will be in place. Road users travelling clockwise between junction 25 and junction 27 will be diverted via the A10, the A406 and the M11 northbound to rejoin the M25 at junction 27.
Road users travelling anticlockwise between junction 27 and junction 25 will be diverted via the M11 southbound, A406 and the A10 to rejoin the M25 at junction 25.
Road users wishing to use the clockwise junction 26 entry slip road will be diverted via the A121, A104, A406 and M11 to rejoin the M25 at junction 27.
Road users wishing to use the anticlockwise junction 26 entry slip road will be diverted via the A121 and the A10 to rejoin the M25 at junction 25.
Road users travelling on the M11 northbound and wishing to join the M25 anticlockwise will be diverted onto the M25 clockwise to junction 28. Then join the anticlockwise carriageway and follow the above diversion, or join the A12 southbound to join the diversion mid-way.
Members of the public should contact the Highways England customer contact centre on 0300 123 5000.
Journalists should contact the Highways England press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.