The Washington Post reports:
Every inauguration presents huge security challenges because of the large, open areas the new president traverses and the large number of visiting dignitaries. A massive crowd presents further complications. The Secret Service and other agencies must increase the number of undercover agents they have mingling among the spectators, officials said. And even if a small incident occurs, people could be trampled in a panic.
The threats aren't limited to violence or terrorism: Freezing or rainy weather could send people fleeing for shelter or medical attention. The D.C. Fire and Emergency Medical Services Department is among the many agencies across the region gearing up for demands. And the crush of traffic will put additional pressure on police and transportation officials.