Packed into a subway train that has broken down, or stuck in gridlocked traffic, it's easy to spot one key aspect of London's 2012 Olympic Games that is causing organisers sleepless nights.
Despite seven years of planning and a colossal budget, transport remains the Achilles heel of preparations that otherwise seem to be progressing well at the 100-day mark to go before the opening ceremony on 27 July.
"Keeping the capital moving smoothly during the Games will be nothing short of a Herculean task," the London Assembly, which oversees the work of the mayor, warned last month.
"Given the scale of the challenges, some disruption to the transport network is inevitable," it added.
London's trains, underground train system and buses suffer from decades of under-investment and already struggle to cope with the 12 million journeys made each day, with the Tube in particular regularly breaking down or suffering delays.
During the Olympics, the network will have to deal with an extra three million daily journeys, as 10 500 athletes, 9000 officials, 20 000 journalists and hundreds of thousands of spectators descend on the 13 Olympic sites across the capital.
Faced with the hideous prospect of athletes missing events while stuck in traffic or in a tunnel, London's transport authorities have embarked on a huge £6.5-billion modernisation programme.
A legacy for London?
The budget, drawn up after London won the bid in 2005, is the equivalent of two-thirds of the money spent on the rest of the Games - and Transport for London, which manages the network, is confident it will bear fruit.
TfL's director of Games transport Mark Evers told AFP that they had been preparing for the Olympics for the last seven years.
"We're really confident that the London public transport and the roads network will cope during the Games," he said.
As part of the often disruptive works programme, road junctions have been reorganised, Stratford station next to the Olympic site in east London has been extensively renovated, and existing train lines have been extended.
Extra buses, trains and Tubes will be laid on during the Games, while the high-speed Javelin shuttle service will whisk passengers off Eurostar trains coming from France and Belgium, directly to the Olympic site.
Is Heathrow up to it?
Lawmakers have also expressed concern that London's Heathrow airport, already the busiest in the world in international passenger terms, will be unable to cope when 17 000 athletes and officials depart on August 13.
The issue is not just capacity, however - negotiations are currently under way with transport workers' unions who are demanding extra pay during the Games, to prevent the nightmare scenario of a strike.
TfL has sought to reduce the number of non-Olympic passengers who use the network by urging Londoners and commuters to travel by foot or by bicycle where possible during the 17 days of events.
It has also called on companies to offer employees the option of working at home or at least working flexible hours to ease rush-hour congestion.
To be on the safe side, tens of thousands of VIPs will be given access to 48 kilometres of special Olympic road lanes to help ease their journey through the capital, with 4000 cars and 1500 coaches hired to take them to the Olympic venues.
The plan has sparked strong criticism, particularly from taxi drivers who will not be allowed in the fast lanes, even if London's authorities insist that 70 percent of the road network will not be affected by the Olympics.
John Thomas, chairman of the Licensed Taxi Drivers Association, questioned why the VIPs had not been given hotels closer to the Olympic sites to avoid the need for such measures.
"London will be totally and completely gridlocked," Thomas told AFP.
Mayor of London Boris Johnson has dismissed such fears as "complete and utter nonsense" but traffic monitoring company Inrix forecasts a 33-percent increase in jams during the end of July and the beginning of August.
Tony Travers, a transport expert at the London School of Economics (LSE), said it was very difficult to predict how the transport network would cope.
"We'll only find out when it happens," he said.