A Washington Metropolitan Transit police officer patrols in a Metro subway station following the bomb blasts in London

American commuters made their usual trips by bus, train and subway Friday under stepped up security in many locations.

"I do have some concerns but I trust in the Lord and we prayed and I am going to get on the train like I am supposed to get on there," said one woman in Chicago who went to work very mindful of the carnage that took place Thursday in London.

U.S. officials raised the terror alert level for mass transportation systems from elevated to high in the wake of the London attacks.

Homeland Security Secretary Michael Chertoff told NBC television that security is being beefed up even though there are no specific threats targeting rail, subway or bus systems. "Having obviously observed what happened in London and being mindful of the traditional tactics of terrorists, which are to do coordinated attacks or second wave attacks, we thought it would be prudent to step up the alert level with respect to mass transit, at least for a period of time, so that we can intercept or deter any copycat attack," he said.

Additional police, some armed with automatic weapons and accompanied by bomb-sniffing dogs, were visible at many high profile mass transit locations. Commuters have been urged to report anything suspicious as soon as they see it.

The focus on ground transportation has also re-energized a debate over whether the government is providing enough money to adequately protect the massive mass transportation sector.

Security analysts note that the aviation industry has received about $18 billion in federal funding since the 2001 terrorist attacks while ground transit agencies have only received about $250 million.

Hillary Rodham Clinton (File photo)

Senator Hillary Clinton, a New York Democrat, is among those calling for more money for bus, rail and subway protection. "We got an assurance from Secretary Chertoff that this would be a high priority and that it would be included when the president's budget came for homeland security. But the fact is the president's budget calls for a $50 million cut," she said.

Secretary Chertoff says there will be more money made available to mass transit systems and says the Bush administration's proposed budget includes an additional $600 million for general infrastructure protection, which includes mass transit systems.

But security experts caution that no amount of money can make public transportation completely safe from terror attacks. "How many trains are there? How many train stations are there that need to be protected? So you would say that there are millions of possible targets in the United States," said Georgetown University Professor Raymond Tanter, who served on the National Security Council during the Reagan administration. "So public transport is one way of bringing down an industrialized democracy that depends upon interdependence, communication, travel and the like."

The American Public Transportation Association, an independent group that represents mass transportation systems around the country, says transit systems nationwide need about $6 billion in safety improvements with a special emphasis on hiring more police officers.