M25 and M1 delays expected due to abnormal load's overnight journey
A 50m-long (164ft) piece of equipment is expected to cause delays on the M25 and the M1 while it is transported to a power station.
The 350-tonne load will depart from the Port of Tilbury in Essex on Saturday afternoon on its way to a site near Bedford.
Police will escort the equipment on its 79-mile (127km) journey after a previous delivery was postponed.
Road closures are expected from 20:00 GMT.
The equipment is due to begin its 18-hour journey at about 16:00 GMT on Saturday and the plan is for it to arrive at the site - which is near the villages of Stewartby, Millbrook and Marston Moretaine - between 10:00 GMT and 12:00 GMT on Sunday.
It will be the second of three trips, with the first completed successfully in February. It will have an impact on motorists in Essex, Hertfordshire and Bedfordshire.
The equipment is for a new "rapid response" power station at Rookery South Pit.
National Highways said the load would include parts for Millbrook Power Station. When it is completed, the power station will provide enough electricity to power 150,000 households.
"This has been chosen as the safest route for the convoy to take and will move very slowly while it is on the road," a spokesperson said.
Drax, the company behind the project, said work had started on the site and it was due to open later this year.
What closures are planned?
• The M25 between Junction 21a and Junction 19 will be closed in both directions between 22:00 GMT and 06:00 GMT.
• The exit slips from the M1 onto the M25 at Junction 6a will be closed in both directions between 22:00 GMT and 06:00 GMT.
• The entry slip from the A12 onto the M25 anti-clockwise at Junction 28 will be closed between 20:00 GMT and 05:00 GMT.
• A temporary holding delay of about 30 minutes at the Gallows Corner roundabout on the A12 is "likely" to occur at about 22:00 GMT.
Follow East of England news on Facebook, Instagram and X. Got a story? Email [email protected] or WhatsApp 0800 169 1830