Motorists are being warned to expect delays when an abnormal load from Northumberland completes the last stage of its journey to Surrey on Saturday and Sunday.
Traffic on the M25 in Surrey could be disrupted on 12-13 October as pods for a community hospital development are delivered to the site in Woking.
The width of the units mean they will need a police escort as they are brought from north-east England in two separate convoys.
They will join the M25 at junction 16 (Denham) and will make their way to junction 12 before heading south on the M3, exiting at junction four.
They will proceed along the A331, A31 and A3, before coming off at the Ripley junction before turning and travelling south on the A3 to the Stoke Junction with the A320, where they will travel to their final destination of Woking Community Hospital.
The Woking one-way system will be temporarily held so the loads can be transported through the town to the hospital.
It means no vehicles other than emergency vehicles will be able to enter or leave the hospital between 10:00 and 14:00 BST on Saturday and Sunday, with patients being asked to use the Heathside car park nearby.
A spokesperson for the Woking Community Diagnostic Centre development said: “This weekend we reach an important milestone in the development of a Community Diagnostic Centre in Woking.
“The transportation of units of this size requires a multi-agency approach to ensure that they can be delivered and installed as safely as possible.
“Whilst vehicle access to the site will be impacted, we still urge patients to attend their appointments, including vaccination appointments at the GP practices, and attend the Walk in Centre if they require emergency care.”