Up to 2,300 runners are expected to take part in the fourth running of the half-marathon, which starts on the western (Chepstow) end of the Severn Bridge, on the motorway itself, and finishes, after crossing the bridge and back, below junction 2 of the M48.
The half-marathon will start at 9am and the 10k event, new for this year, will start at 9.45am.
On the day, the bridge will be fully closed to traffic between 7.30am and 11.30am, with a clearly signed diversion route in place during the duration of the closure. The eastbound footpath and cycle track will also be closed between 9am and 3pm.
Gareth Price, south west emergency planning officer for Highways England, said: “We’d like to remind road users to plan ahead – more than 2,000 people are expected to take part, and as well as the bridge closure, local roads are also expected to be busy before and after the race.
“Our advice is to check our traffic and travel information channels, set off early and allow plenty of time.”
Drivers can get up-to-the-minute travel information by phoning the Highways England Information Line on 0300 123 5000 or by accessing the Traffic England website.
Further information regarding current and planned roadworks in the South West region plus neighbouring regions can be found on the Highways England website.
More details on the Severn Bridge half-marathon and 10k can be found on their website.
Members of the public should contact the Highways England customer contact centre on 0300 123 5000.
Journalists should contact the Highways England press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.