Up to 40,000 people are expected at the Flagship Twelfth parade in Limavady on Saturday.
More than 100 bands and lodges will take part in the event.
The route will take the participants through the centre of the town. While local traffic will be facilitated, motorists can anticipate some disruption and should plan their journeys accordingly. Motorists are advised to seek alterrnative routes to the by-pass and those attending event are asked to follow directions of police officers and parade marshals.
Chief Inspector Tony Callaghan, the Limavady area commander, said that police had met with organisers in the run-up to the parade.
“We are working with organisers and partners to ensure a well planned event. The safety of all, whether they are participants, spectators or residents, is a key issue for us at this and other parades.
“There is a particular need for motorists and pedestrians to be on the alert for each other. That means drivers being patient and taking time to allow onlookers and those on parade to clear the roadway before moving off or continuing a journey and those on foot keeping a keen lookout before crossing the road
“In terms of the event, it is an offence to carry alcoholic drink on the parade route. Both police and organisers will take steps to enforce this ban. We will seize alcohol where necessary.
“We are asking all of those who will be in Limavady on the day to show care and consideration for each other.”