Drivers are being warned of overnight closures at the Dartford Crossing over the weekend.
The Queen Elizabeth II Bridge will be closed between 22:00 BST on Saturday and 05:00 on Sunday, with southbound traffic diverted through the east tunnel and northbound traffic through the west tunnel as usual.
The east tunnel will then be closed from 22:00 on Sunday to 05:00 on Monday, with vehicles higher than 4.8m (15.75ft) following a signed diversion route.
National Highways said it was carrying out an "extensive programme of repairs and maintenance work over the next several years" to keep journeys safe and reliable.
The work on Saturday includes expansion joint repairs, structure cleaning and routine maintenance.
Meanwhile, the work on Sunday will include lighting checks, routine maintenance and cleaning, traffic cell checks and high voltage electrical maintenance.
