WASHINGTON (AP) - Anticipating another holiday travel crunch, President Bush on Tuesday said his administration is taking steps to prevent the frustrating flight delays many travelers experience at U.S. airports.

The marquee item in his strategy for reducing air traffic congestion during the busy Thanksgiving and Christmas holiday seasons is the temporary opening of airspace typically dedicated to the military to commercial airliners. Last year, the Pentagon freed up two East Coast corridors during Thanksgiving; Bush said that was being expanded this year to also include the Mideast, the Southwest and the West Coast, including the skies around Los Angeles and Phoenix.

The military uses the space for exercises, but often makes some available to commercial planes on an ad hoc basis. This move would allow airlines to count on the extra room in the skies, particularly helpful if bad weather materializes.

"A lot of our citizens are nervous about travel," Bush said in remarks before hundreds of employees at the Department of Transportation. "They are saying `Will traveling home for the holidays be a wonderful life or will it be the nightmare before Christmas?"

With planes expected to be about as crowded this year as last, the president announced other steps - most already in the works or tried before - aimed at easing any problems.

He said his administration is working with the Federal Avaition Administration, the Transportation Security Administration and the airlines to make more staff available, which would help speed check-ins and boarding.

In addition, he announced he had signed an executive order to making the modernization of the nation's avaiation infrastructure "a leading priority" for all federal agencies. "Modernizing our aviation system is an urgent challenge," Bush said.