Highways England has reminded drivers that the southbound Dartford Crossing is due to be closed overnight on Saturday for a new gantry to be installed.
The closure of the QEII Bridge is due to be in place from 10pm on Saturday until 5.30am on Sunday, although the exact timing of the closure will be subject to traffic levels.
The gantry being installed at Junction 1a of the M25 will house information signs for drivers.
The southbound M25 will be closed from Junction 30 to Junction 1a, with a clearly signed diversion in place via the A13, Blackwall Tunnel and A2 to the M25 Junction 2.
Following the planned closure, between 5.30am and 8am, only one lane will be open over the QEII bridge. This is so structural surveys can be safely carried out on a footbridge between Junction 1a and 1b.
The M25 clockwise Junction 31 entry slip road will also be closed at the same time, with a diversion in place to Junction 30 instead.