LONDON, England (AP) — Long lines were formed today and travellers were delayed at St Pancras, the central London rail station where reporters, Olympic workers and fans with tickets depart for the Olympic Park in east London.

The delays caused two AP reporters and scores of other travellers to take at least 50 minutes to make the six- to seven-minute ride out to the Olympic Stadium. Other riders complained on Twitter about delays of up to two hours, and barricades were put up to control the crowds at the train station.

Hours later, officials acknowledged that delays up to an hour were continuing Tuesday night, blaming signal problems.

Three days before the Olympics officially begin, London’s extensive subway and train system is facing a major test with officials expecting up to three million more journeys a day during the games.

A spokeswoman for Southeastern, the company that operates the route, said there were problems outside London and further down the track that affected the new high-speed “Javelin” train. The train left nearly an hour after its departure time.

London transport officials already conceded earlier today, that Olympic fans and millions of working Londoners — including Prime Minister David Cameron — will bustle and battle to get about.

“It will get busy,” the city’s transport chief, Peter Hendy, told reporters at the main Olympic press centre. “It has got busy already. There will be some queues.”

The “Javelin” service aims to move around 25,000 people an hour at peak times to the Olympic Park at Stratford in the east of the city. The service is set to run 24 hours a day and has planned 200 extra trains every day during the Olympics, offering a total of 6.2 million extra seats.