Officials now face heightened emphasis on protecting 80,000 spectators in new stadium scheduled for completion before 2012 Summer Games. (Photo courtesy of London 2012)

London's mood went from elation to gloom as yesterday's news of the city's selection as Olympic host for the 2012 Games was swept aside by today's rush-hour attack on the capital's transportation system. With security already a major issue for the Olympic planners, the terrorist incidents will sharpen concerns, particularly over safeguarding the city's vast subway system, which must be expanded ahead 2012.

Explosions at three London Underground metro sites and on one city bus caused at least 33 deaths, 45 serious injuries and 300 other casualties according to initial official estimates. Two explosions hit trains between stations, one near the surface and one in a deep tunnel. The third bomb was at a surface station outside the centre. The bombs led to the city's entire underground and surface transportation systems being shut as precaution.

A day after announcing, in Singapore, London's narrow victory over Paris to host the 2012 Games, International Olympic Committee President, Jacques Rogge sent the city a message of sympathy. Having celebrated its success, London's Olympic bid team was still returning from Singapore to get the project moving.

With the Games planned for several hubs, transportation will be a major element of their planning. Underscoring the point, Transport Commissioner Bob Kiley today confirmed Mayor Ken Livingstone's plans to invest around nearly $20 billion on transportation, including extending the subway system east towards the planned Olympic Park, some 14 km from the centre.

The park, calling for redevelopment of 200-ha of brownfield land at the Lower Lea Valley, will include the main new venues. The largest will be the 80,000-seat Olympic Stadium, which has undergone a conceptual design by HOK+Sport+Venue+Event, London.

With construction not due to start on the estimated $465 million stadium till 2008, the planners will have time to review security measures. Of the other 32 venues, 15 already exist with two needing work. Another six new projects are in construction or committed and two, permanent more facilities are needed.

While the U.K. government will contribute to the Games' financing, augmented by London's Mayor, it will also have overall responsibility for security. A subsidiary Security Directorate, to be set up by the Games' organizers, will establish and implement the strategy, with design and construction being a focus in the development phase up to 2008.