The A1M and M25 South Mimms Junction will be closed overnight starting Monday.
Highways England will be carrying out works to reduce congestion and improve safety, as part of its junction improvement programme.
The A1M southbound entry slip road will be closed overnight, between 10pm and 5.30am, for four nights.
A diversion will be in place via the A1M Junction 2 and return.
The roundabout carriageway clockwise between the entry slip road and anti-clockwise exit slip road will also be closed overnight, between 10pm and 5.30am, from Wednesday August 21 for two nights.
A clearly signed diversion will be in place via the A1M junction 2 and return.
Similarly, the M25 anti-clockwise exit slip road will be closed between 10pm and 5.30am, for four nights starting Monday.
A diversion will be in place via the M25 Junction 22 and return.
For up to date info, please go online to: highwaysengland.co.uk/traffic/.
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