Motorists have been warned about road closures as a 255ft-long (78m) load is moved between Shoreham and Henfield in West Sussex.
The electricity transformer, which is 15ft (4.6m) wide and weighs 331 tonnes, left Shoreham Port at 05:30 GMT and is expected to arrive in Wineham Lane at about 13:00, Sussex Police said.
The load will use the A259, A293, A270, A27 and A23 before joining the A272.
Roads will be closed on the route throughout the day, police said.
Sgt Dan Pitcher, of the East Sussex Roads Policing Unit, said: “This is a substantial load and to ensure the safety of all motorists we will enforce rolling road closures and periodic full road closures on the route throughout the day.
“This will of course cause some delays, and we’d like to thank all road users in advance for their patience and understanding.”
- Depart Shoreham Port Left on to A259
- Right into A293 Church Road then Trafalgar Road
- Right on to A270
- Left on to A293 up to Hangleton Interchange then A27 and joining the A23 northbound
- On to the A272 for approx 2.2km
- Left on to Wineham Lane, Henfield
- Left on to the access road for the National Grid, BN5 9AZ.
(From Sussex Police)