The M25 will be closed for three nights this week.
The clockwise M25 will be closed between junction 19 and junction 21a on Monday, Tuesday and Wednesday night.
Work by the the Highways Agency is set to take place between 10pm and 5.30am.
The Highways Agency has put a diversion in place and this will take drivers off the M25 at junction 20, on to the south-bound A41, towards Watford, and then on to the A405 North Orbitial Road towards Junction 21a.
The Highways Agency will be using 3D scanners to map out the bridge and this can help engineers with future repair works.
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