Ironman triathlon: What you need to know about today's event

More than 2,000 athletes will be swimming, cycling and running their way through the day for the extremely tough physical challenge and vying for one of the 30 qualifying slots that are up for grabs in the 2022 Ironman 70.3 World Championships.

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Just reading what they have to do today is enough to make you break out into a sweat - a 1.3-mile swim, a 56-mile cycle ride and a 13.1-mile run.

They start with a swim - from 7.20am - at Preston Beach opposite the Sea Life Centre before taking to their bikes and following a course via Osmington, Crossways, Puddletown, Piddlehinton, Pulham and King's Stag then back down on the Old Sherborne Road to Charminster, to the east of Dorchester onto the A352 and back to Preston and Weymouth via Whitcombe and Coombe Valley.

The run is a two-and-a-half loop course from Lodmoor Country Park to Overcombe then back along the seafront to the town centre where it is expected most of the spectators will be cheering on the participants.

The finishing point is in front of Weymouth Pavilion and, amazingly, the first finisher is expected at 11.15am. Runners will be coming in up to 4.20pm.

Of course all this means it's going to be a different Sunday as far as local roads and access to some services are concerned so it's recommended you check before travelling.

This includes people travelling to Tankfest which continues at the Tank Museum today.

READ MORE: Tankfest urge vistors to 'check their route' ahead of weekend festival

Meanwhile, the railway line to Wareham on the Waterloo line is closed for engineering works with buses operating from Weymouth and Dorchester South to Wareham, where trains towards Bournemouth and London can be picked up. See our story here.

Ironman organisers have produced road closure maps, below, with information for local residents to be aware of allowing them to plan their travel arrangements.

Most closures are in place for Sunday morning only and will be lifted by early afternoon or earlier.

The only road closed all day is Greenhill (from Westerhall Road) and Preston Beach Road to Overcombe Corner (shut 4am-6pm).

Preston Road (B3155) is closed from 6.30am-2pm. There will be no access to Overcombe/Bowleaze until 2pm.

Littlemoor Road will be closed eastbound only (Coombe Valley Road/Chalbury Corner end) until 1.45pm and the A353 to Osmington and Warmwell is also closed eastbound only until 10.15am.

Other closures affect rural routes outside Weymouth and Dorchester. The A352 between Dorchester and Broadmayne is closed until 1.30pm.

Main roads the A37, A356, A35, A354 (Weymouth Relief Road to Dorchester) remain open. The A352 between Sherborne and Dorchester is also open.

READ MORE: Ironman: What roads will be closed and when

Pedestrians can cross the course at any time when it is safe to do so.

Motorists are advised to not park on the bike course.

Emergency services can access the course at any time and essental access for carers has been facilitated.

Some bus services will be affected by the event - see here for the changes, and other timetable changes taking effect from today.

There will be no access to Weymouth tip today while Dorchester tip access will also be disrupted. Dorchester residents are advised to either not travel there today or use an alternative facility.

The car park at Lodmoor is closed today although attractions at the Country Park, such as the Sea Life Adventure Park, are open.

If you're driving use the Park & Ride or town centre car parks instead and allow extra time for your journey.

For more information about the event visit https://www.ironman.com/im703-Weymouth