Washington is used to handling large crowds, from hundreds of thousands of antiwar demonstrators to marchers on both sides of the abortion debate to July 4th frolickers who fill the Mall yearly.

But Saturday's dedication of the National World War II Memorial will be different. The ceremony is only an hour and a half long, but the planning for an expected crowd of 200,000 people that will consist largely of octogenarians has almost redefined the term "logistics."

Among the unusual features of the celebration will be a paramedic bike patrol toting external defibrillators; a team of missing-person detectives to track down elderly visitors who get lost or end up in a hospital; and roving grief counselors for veterans overcome by the emotion of the moment.

There will be a rapid-response team of Metrorail mechanics to fix elevator or escalator outages at stations near the Mall; low-sodium, low-cholesterol offerings by food concessionaires; folding chairs for 117,000 spectators; 400,000 free bottles of water; cooling tents; wheelchair ramps; and motorized stretchers. Notes have been sent by many tour leaders to their elderly charges: Bring appropriate medications, a hat for the sun, an extra pair of eyeglasses, a brief medical history and a primary care physician's telephone number.

"I'm really not very worried about a lot of things because we have worked so hard and for so long that we really have covered a lot of bases and thought about a lot of problems or scenarios," said Betsy Glick, spokeswoman for the American Battle Monuments Commission, which oversaw the fundraising and construction of the $174 million memorial and is sponsoring the dedication ceremony.

"But I do pray for a nice, partly sunny, mild-temperature day on Saturday," she said. "That's what I worry about."

And she should be worried, weather forecasters say.

The weather over previous Memorial Day weekends does not bode well, said Ed Adams, the manager of forensics services at AccuWeather.

"The odds are if you don't have a hot weekend, you're going to end up with a wet weekend," said Adams, who reviewed weather patterns on Memorial Day weekends for the past four years and found either rainy days or high temperatures.

"There's not a very good chance that you're going to get through a whole [holiday] weekend cool and dry," he said.

The weather is the variable no one can control for the dedication of the memorial. But just about everything else has been considered. One tour company bringing in 205 veterans and their caregivers from around the country will send the vets to the ceremony armed with bag lunches containing healthful sandwiches, oranges, granola bars and two bottles of water. It has even sent out a don't-worry-the-cicadas-are-harmless flier.

Speakers at the dedication ceremony, scheduled to begin at 2 p.m., will include President Bush, actor Tom Hanks, TV news anchor Tom Brokaw and the co-chairmen of the fundraising committee for the monument, former U.S. senator Bob Dole and FedEx Chairman Fred Smith. The ceremonial bands of the Military District of Washington will perform musical tributes. Former presidents George H.W. Bush and Bill Clinton and dozens of members of Congress are expected to attend, Glick said.

But the guests of honor will be the thousands of World War II veterans -- the youngest believed to be 76 and most several years older -- and the other men and women who actively worked in the war effort. Sixty-five percent of the 117,000 free tickets for seats at the event were requested by that age group, Glick said. Among the ticketed people, 2,500 use wheelchairs, at least 1,740 use canes, 14 use walkers, 39 have oxygen tanks and three have seeing-eye dogs, she said.

That doesn't include the thousands of participants who are expected to fill the non-ticketed grassy viewing area just east of the Washington Monument and 15th Street and to visit the Smithsonian Institution's National World War II Reunion festival from Third to Seventh streets NW, across from the U.S. Capitol.

Organizers are asking younger visitors to be indulgent, said Bill Line, a spokesman for the National Park Service, which will take over management of the memorial after the dedication. "Obviously, the World War II generation may not be able to move as fast as others. We would ask other people not of that age group to exercise extra patience in honor of" them, Line said. "This is their memorial."

Metro has factored that into its plans. Twenty-five of Metro's buses -- part of a fleet of 300 buses from across the region contracted to shuttle ticketed participants from Metrorail stations to the Mall -- were retrofitted to accommodate the disabled just for Saturday. Buses that normally have 42 seats instead will hold 15 wheelchairs, said Metro spokesman Steven Taubenkibel.

The "dwell" time -- the time that train doors remain open to allow passengers to exit and enter -- will be lengthened slightly Saturday, and rail car operators will make extra announcements to ensure that riders headed to the Mall are on the right train and get off at the appropriate stop, Taubenkibel said.

Emergency medical technicians, nurses and Metro Transit Police will be posted at key rail stations, as will Metro personnel hand-selling Farecards and handing out walking brochures.

"It's going to be an all-hands-on-deck effort from Metro on May 29," he said.

Multiple command centers involving law enforcement, transportation, emergency and medical personnel will be established. There will be nine medical stations on the Mall, each staffed with a doctor, two nurses and land lines in case cell phones don't work. And medical personnel also will be stationed around Washington National Cathedral, which will hold a 10 a.m. interfaith service to be televised on the Mall; at MCI Center, where a ticketed musical performance will be held, also at 10 a.m.; and at Robert F. Kennedy Memorial Stadium, a staging area for buses bringing in participants.

The D.C. Department of Health will hand out fliers at Metro stations outlining heat stroke symptoms and will have a cadre of psychiatric social workers on call -- separate from the 30 grief counselors to be supplied by the Department of Veterans Affairs Readjustment Counseling Office. Ambulances will be parked along the Mall, and evacuation routes to nearby George Washington University Hospital and Georgetown University Hospital have been mapped.

U.S. Park Police and D.C. police have canceled leave for officers, and U.S. Capitol Police are contributing a large contingent to provide extra security for the event.

Even security measures have been adjusted for the age of the audience. The flow rate through metal detectors has been dropped to 250 people an hour from the usual 350. The three entry gates for ticketed participants will open at 8 a.m. for the 2 p.m. dedication, to give everyone enough time to get in. And there will be 40 lanes leading to security checkpoints along Independence Avenue and 60 more along Constitution Avenue to shorten the waits, said Sgt. Scott Fear, a Park Police spokesman.

Only those seated closest to the dedication ceremony stage, along 17th Street across the street from the World War II Memorial, will have to go through metal detectors. But everyone coming to the Mall -- ticketed or not -- will have to go through some level of security check, Fear said.

"We do a lot of major spectator events, and we aren't alarmed by the crowd size at all," said Acting U.S. Park Police Chief Dwight Pettiford. "My main concern is the safety of the individuals."

Ian Delange of B&K Rentals works on a tent near the National World War II Memorial that will house the stage for Saturday's dedication.A pair of visitors consider the National World War II Memorial from the shady refuge of a park bench. Organizers are hoping for mild weather for the memorial's dedication.Taking a page from the Vietnam Veterans Memorial, visitors have begun to leave mementos at the World War II Memorial.