Police are advising motorists of possible delays and some road closures ahead of the Eastern Electrics event which is taking place at Hatfield House tomorrow.
Thousands of people are expected to attend the event, and it is predicted that there will be heavy congestion between 10am and 12pm, and 9pm until 11pm.
The A1000 Great North Road will be closed at the junction with the B6426 St Albans Rd East to B197 French Horn Lane. Access will be maintained for residents and the train station, with a diversion in place using B6426 St Albans Rd East and B197 French Horn Lane.
In addition, a lane closure will be in place on the A414 Hertford Rd, westbound.