SINGAPORE - The downtown city area will be bustling this weekend with four major events taking place at the same time; the Standard Chartered Singapore Marathon (SCSM), U2 Joshua Tree Tour, C3 Anime Festival Asia (AFA) and Gardens By The Bay's Christmas Wonderland.

This unprecedented convergence of schedules is expected to see hundreds of thousands throng the area, resulting in one of its busiest periods.

As a result, the respective organisers have moved to advise its event-goers on the risk of potential congestion.

Geoff Meyer, managing director of Asia for the Ironman Group that manages the SCSM, on Thursday (Nov 28) urged Singaporeans to gather along the race route and enjoy the "unprecedented mix of performances, food and activities" across three dedicated spectator zones - The Promontory, Empress Lawn and The Float. These include live bands, games for the family, and an LED Lion Dance performance.

Previous editions of the SCSM, first held in 1982 as the Singapore Marathon , usually saw the marathon begin before dawn but this year's 42.195km marathon, half-marathon and Ekiden relay races will flag off at 6.05pm at the F1 Pit Building on Saturday (Nov 30).

The shift is part of the effort to fulfil various criteria in the organisers' bid to get the SCSM listed among the Abbott World Marathon Majors, a series of the most prestigious marathons in the world.

Major road closures will begin from 1pm on race day, starting at the Marina Centre zone, and normal traffic activity will resume by noon on Sunday, after the 5km and 10km races.

"We've worked closely with stakeholders and the authorities to ensure the spectator zones, start and finish lines are easily accessible by public transport," said Meyer.

"We are expecting over 100,000 people coming out to support the race, as friends, family and community spectators come together to show the world our Singapore spirit and join in the next evolution of one of the world's great running events with our brand new evening flag-off."

When Ironman announced road closures earlier in November, it advised those who wish to drive into the downtown city area to rely on mobile phone apps like Google Maps or Waze for navigation.

Marathon participant Gwen Lim, 38, said she intended to drive to the event and added: "I'm a little bit apprehensive because I might have trouble finding parking lots.

"I've checked the apps and where to park, but I don't know how tired I will be walking back to where I parked after a full marathon.

"But everyone I know participating is excited how to see this night race turn out."

About 50,000 participants are expected to take part across all the race categories, and this is also roughly the same size of crowd expected each weekend night at the National Stadium for the U2 Joshua Tree Tour.

The concert will commemorate the 30th anniversary of the Irish band's 1987 mega selling album of the same name.

Partly because of the road closures for the SCSM, the Singapore Sports Hub has also advised concert goers to use public transport and to arrive at least two hours before the U2 show. The nearest MRT stations to the stadium are Kallang (EW10) or Stadium (CC6).

Another large mass of event-goers is expected at the three-day C3 AFA Singapore, which starts on Friday and takes place at the nearby Suntec Singapore Convention and Exhibition Centre.

Last year's event attracted over 105,000 fans and participants, and Mr Shawn Chin, AFA festival director, said organisers are expecting "the same, if not better" visitorship.

Mr Chin said organisers have not received any concerns from event-goers on transportation arrangements, but shared details on how attendees can get to the event venue on its social media platforms and website.

Meanwhile, the sixth edition of the Christmas Wonderland at Gardens by the Bay, opens on Friday and will also draw huge crowds. In 2015, the month-long event drew 1.2 million.

Kevin Soh, director of organisers Blue Sky Events, said it was unable to give an estimate of expected numbers, but added: "We are pleased that our pre-sales are tracking higher than last year, and we look forward to once again presenting a spectacular line-up of experiences at Singapore's biggest year-end holiday event."