Philadelphia ? Despite significant improvements to levees and floodwalls in New Orleans, if Katrina hit again, the city would not be fully protected.

And the lack of a single agency to oversee hurricane protection leaves New Orleans especially vulnerable to disaster the next time a major hurricane strikes.

“Nobody’s in charge,” said Robert G. Traver, an associate professor of civil engineering at Villanova University and one of 14 members of the American Society of Civil Engineers’ external review panel monitoring the work in New Orleans. “There needs to be a single agency or official in charge of levees and pump stations and evacuations – everything.”

The Army Corps of Engineers, with $5.7 billion in federal funds, has rebuilt, raised and strengthened most of the existing system of levees, floodwalls and floodgates. About 220 miles of the 350 miles of levees in New Orleans have been restored to pre-Katrina strength or better.

The three vulnerable canals overwhelmed by Lake Ponchartrain’s storm surge have been upgraded and isolated.

Such improvements are designed to reduce, but not eliminate, death and destruction in a Katrina-like storm.

If the levees and pumps had not failed during the storm, when they were overtopped by the surge of water, about 800 lives would have been saved, according to analyses by a Corps-commissioned task force. As it was, about 1,400 people died.

By 2010, the Corps says, it will have improved the storm-and-flood protection system that surrounds New Orleans to protect the city against a 100-year storm. Floods are measured by their predicted frequency; a 100-year storm is so severe that it is estimated to have a 1 percent chance of occurring in any given year.

In New Orleans, there is no plan to make the levees and floodwalls high enough and strong enough to protect against a Category 5 hurricane, one with winds greater than 155 mph winds and storm surges greater than 18 feet above normal.

Only three Category 5 hurricanes have hit the U.S. since records began: The Labor Day Hurricane of 1935, Hurricane Camille in 1969 and Hurricane Andrew in August in 1992. Although Katrina reached Category 5 in the Gulf of Mexico, it was a Category 3 hurricane by the time it hit the northern Gulf coast. Its storm surge remained at the level of a Category 5 storm.

Congress has directed the Corps of Engineers to present a plan by December 2007 for protecting Louisiana from a Category 5 hurricane.