Motorists face months of disruption on several rural routes as lorries deliver huge pieces of equipment needed to lay massive electricity cables through the Norfolk countryside.

The power lines, connecting a wind farm off the coast to the national grid, are being laid in trenches dug from Weybourne to near Swardeston, south of Norwich.

Eastern Daily Press: Orsted's transport map shows abnormal loads following the A148 and B1149 Orsted's transport map shows abnormal loads following the A148 and B1149 (Image: Orsted)

The project requires regular deliveries of heavy machinery and parts to a central depot at Oulton, near Aylsham, and Orsted, the company behind the work, has revealed details of how and when these abnormal loads will arrive at the site.

READ MORE: World's biggest offshore wind farm will be built 75 miles off Cromer coast

Because of the size and frequency of the convoys, they are expected to bring delays for other motorists.

The firm says there will be up to 10 deliveries a week in convoys involving two vehicles at a time, each weighing up to 50 tonnes and measuring 14.7 feet across.

Eastern Daily Press: The Hornsea Three cable route (red) and Orsted's main construction compound in Oulton (circled)The Hornsea Three cable route (red) and Orsted's main construction compound in Oulton (circled) (Image: Orsted)

The equipment is arriving by sea at Boston, in Lincolnshire - which was considered more suitable than Great Yarmouth and King's Lynn - before being put on trucks.

The lorries are expected to arrive in Norfolk on the A17 but will move onto smaller roads to reach the depot, travelling on the B1149 and A148 past Holt and Fakenham.

READ MORE: Bird's eye view of vast trench being dug through Norfolk countryside

The firm says the route has been chosen to avoid weak bridges and height restrictions.

Police officers will be escorting some convoys, with Orsted marshals used to help navigate tight junctions and turnings. 

Each abnormal load will travel during the day. The firm said the "intention" was to avoid rush hours but it could not always guarantee it.

Eastern Daily Press: Orsted is digging tens of miles of trenches to lay high-capacity wind farm cablesOrsted is digging tens of miles of trenches to lay high-capacity wind farm cables (Image: Mike Page)

These deliveries are scheduled to run every week until December, with an average of 10 loads transported per week, subject to weather conditions.

Once completed, the onshore power cable will run for 33 miles (53kms). Most of the cables will be laid into open trenches before being covered up again. 

The line is to connect the national grid with the 231-turbine Hornsea Three wind farm off the north Norfolk coast.

Danish firm Orsted claims the project, costing £8 billion, will power three million homes.