The first Brighton Marathon on Sunday will be marked with street parties, extra trains, revised bus times, suspended parking bays and closed roads.
Sussex Police have spelt out the extent of the impact in a wide-ranging press release as the city prepares for what looks like being a dry, clear day with the lightest of breezes.
The marathon gets under way in Preston Park at 9am with Brighton’s Olympic gold medallist Steve Ovett firing the starting pistol.
It finishes in Madeira Drive, with the fastest runners expected to take between two and two and a half hours.
Many roads on or close to the marathon route will be closed or have access restricted.
Signs are being put up to mark road closures – and the marathon organisers are providing stewards along the route and at all junctions.
Access is expected to be maintained to all side roads although drivers may face diversions.
Access will be maintained throughout the day to Churchill Square and its car parks with staff on hand to help if necessary.
Similarly access will be maintained to Regency Square and The Lanes car parks from the seafront, although traffic leaving will be diverted.
Street parties are being held in five neighbouring Hove streets – Berriedale Avenue, Saxon Road, Braemore Road, Glendor Road and Langdale Gardens.
The Brighton and Hove City Council traffic control centre in Bartholomew House will be manned throughout the day.
Staff will monitor and manage traffic signals to ease traffic flow.
They will also provide up-to-date information about traffic and parking on electronic signs, the Real Time Bus Information System at bus stops and on the Journey On website.
Parking is suspended in some areas along the route where extra road space is needed for the marathon or to ensure public safety.
Any vehicles left in suspended bays will be removed if they are still there on Sunday morning.
Southern Trains will put on two extra early morning services to Brighton from Victoria, two extra from West Worthing, two from Eastbourne and one from Fratton.
