Members of the Sept. 11 commission urged Congress yesterday to impose strict deadlines on the Department of Homeland Security to close loopholes in the nation's transportation system, even if it means going up against powerful interest groups and spending billions of dollars.

The chairman and vice chairman of the National Commission on Terrorist Attacks Upon the United States, which issued recommendations last month, said the administration has not developed strategic plans to protect the nation's rail system and ports and to correct technical communication problems among police and firefighters. The leaders of the commission also said aviation security, which has received the most government attention and money, has focused too much on "fighting the last war" instead of looking to prevent new threats.

The commission told the Senate Commerce, Science and Transportation Committee that it will cost at least $1 billion annually for the next five years in order to close remaining gaps in airline security.

"We are mindful that is a substantial investment," said the Sept. 11 panel's chairman, Thomas H. Kean (R). "But we have seen the devastating costs in human life and economic disruption that result from a successful attack. It is a worthwhile investment, and one necessary to fulfill the government's constitutional duty to provide for the common defense of its citizens."

The Homeland Security Department is already developing a broad plan and individual strategies for each transportation mode, said Asa Hutchinson, the agency's undersecretary for border and transportation security. The work is expected to be completed by the end of 2004. Hutchison said he agrees with the panel's findings and is already working to address its more specific recommendations.

One of the panel's main concerns involved the government's "no fly" lists and lists of other known suspicious people who are supposed to be stopped and questioned at airports. The panel recommended that the government immediately begin comparing every passenger against more comprehensive lists than those currently used at airports, even though some agencies do not want them in the hands of airlines. Airline employees are currently responsible for checking passengers against the lists.

Two of the hijackers involved in the Sept. 11, 2001, attacks were placed on the State Department's terrorist watch list in August 2001, but the names were never reported to the Federal Aviation Administration, according to the commission's report. "This was a missed opportunity to foil at least part of the attack," Kean said.

Hutchinson said the TSA plans to take over checking the watch lists at some point, when it develops a new computer passenger-screening program. The administration's previous attempt, called CAPPS II, has been shelved because of privacy concerns. "We're not just sitting idle," Hutchinson said.

Although the TSA has taken several steps to fortify cockpit doors, add armed air marshals and pilots, and conduct background checks on more airport workers, the agency needs to be more aggressive about checking for explosives, the Sept. 11 panel members said. Passengers and carry-on luggage should be screened for bombs at security checkpoints, the panel suggested, and every airliner should carry at least one blast-proof container in the cargo hold for suspicious packages and luggage.

"TSA is now nearly three years old," said Lee H. Hamilton (D), the panel's vice chairman. "It has done much good work. However, the time for 'planning to plan' is past."

Undersecretary Asa Hutchinson said the department is not "sitting idle."