District officials are seeking to identify neighborhoods that are home to large concentrations of residents who do not own cars, as authorities hope to bolster evacuation plans after the dire problems experienced during Hurricane Katrina.

Tens of thousands of residents were left stranded in New Orleans before and after the hurricane because they did not have access to vehicles.

Dan Tangherlini, director of the city's Department of Transportation, said the survey of neighborhoods would help officials tailor evacuation plans to ensure that District residents can get out of the city.

As many as 35 to 40 percent of District households are without cars, he said, an estimate he based on research by the Washington Regional Network for Livable Communities, an environmental advocacy group.

"We need to know where our underserved population is," Tangherlini said. "And we need to tailor our response to peoples' needs."

Tangherlini disclosed the survey during testimony at a District Council committee hearing in which transportation officials spoke about their preparations for dealing with a terrorist attack.

Council member Carol Schwartz (R-At Large), chairman the council's Committee on Public Works and the Environment, which hosted last Friday's hearing, first scheduled the testimony after the attack on the London subway system in July.

The troubled evacuation before and after Hurricane Katrina, she said, only added to the District's need to ensure that its own strategy is sound.

At times, Schwartz focused the hearing on terrorism, in particular whether Metro planned to institute random bag searches on its trains, as was done in New York following the London attacks.

Richard A. White, Metro's general manager and chief executive, said his agency is monitoring New York's success with the policy in considering whether it is needed in Washington.

"This is still in the staff evaluation process," he said, adding that Metro eventually would present the matter to its board for consideration.

Schwartz said she was not advocating searches, adding that they no doubt would cause long lines and inconvenience riders. But she also said that she personally is comforted by added security on airlines.

"I'm very glad I'm being searched," she said. "I usually thank the people."

Council member Jim Graham (D-Ward 1) urged transportation officials to pay equal attention to the bus system and its 12,500 stops across the District. "It's not all about the subway," he said. "What about our buses?"

District officials have been working on mass evacuation strategies since the terrorist attacks of Sept. 11, 2001.

As a result of Hurricane Katrina, however, Tangherlini said transportation officials have focused on a new area of concern, residents who are without cars.

Working with vehicle registration records, he said his agency would identify those areas in the city that have disproportionately more residents than cars.

"We're trying to plot them on a map," he said.

Based on earlier parking studies, he said, transportation officials believe that the areas with fewest cars are in the "upper reaches" of Wards 3 and 4, as well as in Wards 7 and 8.

With the results of their latest survey, he said the department will develop plans to ensure that meeting points are designated where buses could pick up people who need transportation.

He said the department could also use the survey to coordinate with not-for-profit organizations to provide additional transportation.

But in an interview, he cautioned that an evacuation from the District likely would be far more difficult than on the Gulf Coast, where officials knew for several days about the impending hurricane.

In the District, he said, the most likely trigger for an evacuation would be a sudden terrorist attack, which makes planning "harder and more complex."