During the morning rush hour at the main ticket hall of London's Euston railway station, two teenage girls struggled to carry their luggage to the subway station underground.

It was their first time to London, and they couldn't find the elevator. Two passers-by stopped and offered to carry their luggage down the stairs.

The girls breathed a sigh of relief after they were told an elevator nearby would take them the rest of the way. But a sign said it was out of service due to "a mechanical defect".

The crowd waiting for the Northern Line train began to swell. "Why is the Underground in a so-called international city so disappointing?" one of them asked. "Are they going to be able to cope with the Olympic Games?"

Fears are mounting over the ability of London's subway system to handle crowds during the Olympics, which will begin next month. Overcrowding, overheating and antiquated signaling systems make the subway woefully inadequate to serve a city the size of London.

The subway system had just three problem-free weekdays last year, the Daily Telegraph reported.

The biggest concern is the Jubilee Line, a key Olympic artery linking the main stadium in Stratford and Wembley Stadium through central London.

A meltdown on the line two weeks ago saw passengers being taken off a train and walked through a tunnel to safety.

More than 500,000 "customer hours" were lost on the Jubilee line due to track, train and signal failures last year, according to Transport for London's own statistics.

As the oldest underground railway in the world, the total length of all 11 lines of the London Underground, which opened in 1863, is more than 402 kilometers. It carries more than 3.04 million people a day, according to the TFL's Annual Report and Statement of Accounts 2010/2011.

TFL expects about a million extra visitors in London during the Games, leading to 3 million extra public transport journeys each day.

It has also warned on its website that the Jubilee Line will be "exceptionally busy, particularly in the morning and evening peaks", as spectators travel to and from the Olympic Park in Stratford, North Greenwich Arena and Wembley Stadium and Arena.

The busiest stations are normally extremely crowded during morning and afternoon rush hours.

With only a month to go, the possibility is slim for the authorities to make any changes to improve the subway service dramatically, given London's lack of efficiency in construction.

For example, it took London 18 months to renovate Leicester Square, which is famous for its film premiers in the heart of the city.

The square, which reopened in late May, now has stainless steel railings, 12,000 square meters of granite paving and a water feature around the Shakespeare statue, which sends jets of recycled water two meters into the air. The project cost 15.3 million pounds ($24 million).

In comparison, renovating the London subway is a formidably huge job. There is little hope anything special could happen in one month.

Coming to London to watch the Olympic Games is a great idea, but only when you can use a bicycle, scooter, skateboard ... or anything to help you get around.