Where Do You Park 10,000 Charter Buses?

"There is a dearth of information that transportation planners and bus operators need to help get tourists here for this historic event," said Shosteck, of the bus association. "We're understanding that this is an unprecedented logistical challenge and about getting people to a milestone event in U.S. history, but we're hoping to get some answers so that we can convey that to our operators."

Metro officials want charter bus parking to be spread across the region, with one company directing all of the buses to arrive at staged intervals at designated parking lots.

Tangherlini is not so sure that "precise minute-by-minute" scripting will be workable. "We need something much simpler, more robust, something that can stand up to the vagaries of the weather, the vagaries of traffic, and rolling security."

Metro points out that if too many buses are parked at RFK Stadium and FedEx Field at the same time, for example, the nearby Metro stations and the Blue and Orange lines will not be able to safely accommodate the crush of people.

At RFK Stadium, for example, about 1,200 buses were parked for the dedication of the World War II Memorial in 2004. But now the city is pressing for close to capacity, 1,750 buses, Tangherlini said.

That's 87,500 people. The Stadium-Armory Metro station can handle 13,000 an hour.

Aware of Metrorail's constraints, Tangherlini said, the city is considering bus service between RFK and the Mall, similar to the arrangement for the World War II Memorial dedication.

Staff writers Michael E. Ruane and Brigid Schulte and staff researcher Meg Smith contributed to this report.