For some preparing for the Jan 20 inauguration of Mr Barack Obama as US president, and for the record crowds expected, the biggest preoccupation is where to put those vehicles.

Mr Tangherlini is looking to the neighbouring states of Maryland and Virginia for help in accommodating the buses expected to stream in from across the country.

The possible 10,000 buses, which if parked end to end would cover a distance of 137 kilometres, is just one of the scarily large numbers being crunched by planners.

The US media has mainly focused on one number - the number of people expected to swamp Washington, a city of just 600,000, for the swearing-in ceremony on the steps of the US Capitol.

One thing is certain: Mr Obama's election in November as the country's first black president has generated far more excitement than in recent years over the inauguration.

Some have seized on comments by Washington Mayor Adrian Fenty, who suggested as many as 4 million people could attend.

But the Secret Service, which is overseeing security preparations, said that was overstated.

'We have seen nothing to suggest that it will be 4 million. There is an internal number that the public safety people are using but are not making public,' Secret Service spokesman Ed Donovan said.

But there seems to be consensus among officials that the crowd will exceed the record set during the 1965 inauguration of Mr Lyndon B. Johnson, when 1.2 million people attended.

And Mr Tangherlini said he was planning 'for the extreme'.

The city's metro rail system is confident it can handle the expected surge in passengers. Metro spokesman Steven Taubenkibel said 850 rail cars would be deployed, able to carry 120,000 people every hour.

The Presidential Inaugural Committee is opening the entire length of the National Mall, a distance of about 3km that runs from the Capitol to the Potomac River, to the public for the first time in inaugural history.

That will present a security challenge for the Secret Service and other law enforcement agencies.

'We are going to have a wide variety of security measures in place. If you can than think of it, we will probably be doing it,' Secret Service spokesman Donovan said.

Every one of the 240,000 people expected to attend the actual swearing-in ceremony will be screened by walk-through or hand-held metal detectors, he said.

People on the parade route between the Capitol and the White House will also be screened. Items listed for confiscation include bicycles, pets, backpacks, laser pointers and supports for placards. That is in addition, of course, to firearms, explosives and 'weapons of any kind'. Security officials would not say whether they were taking added precautions this year given several death threats aimed at Mr Obama during the presidential campaign or because of the continued threat of an attack by Islamist militants.

'Taking into account the size of the crowd expected and what is happening internationally, terrorism is always a concern because we are in the nation's capital,' police spokesman Traci Hughes said.

Some 4,000 officers will be on duty on the day, along with 4,000 reinforcements from 96 other law enforcement agencies across the country, she said.

Air Force General Gene Renuart, the commander of US Northern Command, the US military headquarters responsible for protecting the United States, told reporters that about 7,500 active duty US military personnel and about 4,000 National Guard personnel would be involved in the inauguration, either in a ceremonial role or assisting civilian authorities.

Air defence in the area would also be boosted, he said. -- REUTERS