The biggest concern is whether London can cope with the extra influx of visitors. An expected 150,000 spectactors would visit on a busy day, including 125,000 travelling from or through central London.
During normal working months these extra numbers would put an unbearable strain on London's transport network but the Olympics will be held during the quieter holiday months, July and August.
By 2012 East London should also have a pretty comprehensive transport network. Spectators, athletics and media folk travelling to the main Olympic stadium at Stratford will have plenty of travel options. As well as the Central and Jubilee Underground lines, Docklands Light Railway, and two overland commuter lines, Stratford will also be connected to the Channel Tunnel Rail Link by 2007.
As well as being connected to St Pancras and the continent, the CTRL could also be connected to rail lines North of London, which will mean that visitors from the North would be able to avoid the congested Euston and King's Cross stations.
The Tory opposition is suggesting that London's infrastructure will struggle to cope with the Olympics if the Crossrail project is not completed in time. Crossrail would link Heathrow and Paddington to the West of London with Canary Wharf and Stratford in the East and with up to 24 trains an hour it could solve the problem at a stroke. But even if the government did give the project the go-head immediately, it would be hard pushed to finish Crossrail in time for the Olympics.
This is why an Arup report looking at the viability of the Olympics was commissioned by the government on the assumption that Crossrail would not be built. Even without Crossrail Arup concluded that London could cope with the thousands of spectators if they were scheduled to arrive at major events outside of the rush hours.
The government may also be too busy limbering up for an Olympic bid to worry about Crossrail. The high cost of funding Crossrail – estimated to be between £7 and 11bn at the last count – could undermine the government's chances of winning the main event.