All good things must come to an end, even the London 2012 Games. But after the Closing Ceremony on 12 August, a huge crowd of international visitors will be leaving the United Kingdom, straining the city’s transport system.Heathrow Airport is poised for its own Olympic record as it expects 13 August to be possibly the busiest day the airport has ever handled. Passenger volume may break its single-day record of 236,955 passengers on 24 July 2012 -- double the airport’s average for this summer.To cope, Heathrow has built a temporary Games Terminal, separate from its permanentterminals, to handle the 10,100 athletes and Games officials, and their 37,900 bags.This temporary structure is outfitted with 31 check-in desks and seven security lanes. Once athletes and officials pass through check-in and security, they’ll be taken by bus to the permanent departure terminals. The Games Terminal, set up in a car park, will be open for three days starting 13 August.Ordinary travellers will use the permanent terminals, as usual, but the airport has trained 1,000 volunteers from local communities to help spectators get where they need to go. Travellers taking international flights are encouraged to arrive at the airport three hours ahead of departure.Travellers should also consider printing out boarding passes ahead of time to speed up the check-in process, and should remember the rules about packing liquids and electronics in carry-on and hand luggage.Of course, navigating the airport crowds is only part of the journey, and not everyone will depart by plane. Since the true London 2012 exodus begins the moment each traveller steps outside their hotel, here are a few key pieces of advice to help make the easiest exit possible.The subway network, known as the Tube, will be congested and may break the all-time usage record of 4.31 million passengers set on 2 August 2012. That said, service has been relatively good throughout the Games, so that bodes well for departure day. In general, add an extra 20% on to the amount of time you would ordinarily give to get from point to point.Mobile users can sign up for free transport and traffic alerts by visiting the Transport for London website, and laptop users can plan their journey with the Get Ahead of the Games website. Crowding can also mean warmer-than-usual conditions -- carry a bottle of water to stay hydrated.If you are travelling to the airport, take rail options instead of a taxi or the Tube, if possible. Both Gatwick and Heathrow have express rail lines from downtown, namely the Gatwick Express departing from Victoria Station and the Heathrow Express departing from Paddington Station, both of which will be less prone to gridlock than the motorways and the Tube. For other UK airports, Britain’s National Rail offers train service that is speedier than road travel. All of these services sell tickets online, so plan and book your travel in advance.Travelling by Eurostar to destinations on the Continent? Remember that the Eurostar station at St Pancras International does passport checks prior to departure, which can surprise travellers expecting the customs process to take place at arrival. Arrive 10 minutes earlier than you ordinarily would for a Eurostar train to allow time for long queues.After the Games, cross-channel ferry operators will be providing full service to multiple destinations in France, such as Calais and Le Havre. Remember that ferry terminals, such as at Dover and Portsmouth, will be busy and advance booking online is recommended. Several companies provide services, and you can get a sampling of them at booking site FerrySavers.com.Bus service connects London’s Victoria Coach Station to points in downtown Paris and other European cities, and can be booked online through Megabus, Eurolines and iDBUS.