Dulles Airport Helps Travellers Navigate Security Checkpoints

DULLES, VA - JULY 2: A passenger takes off his shoes as other passengers put their carry-on luggage in trays for x-ray inspection before they pass through a security check-point at Dulles International Airport July 2, 2007 in Dulles, Virginia. Homeland Security Secretary Michael Chertoff said airports in the U.S. are tightening security for the week of July 4th holiday, but has no plan to raise the threat level any higher. The national threat level for airports was raised to orange from yellow after British police stopped a plot aimed at blowing up transatlantic flights in August, 2006. (Photo by Alex Wong/Getty Images)