Published: Aug 25, 2011 11:32 AM EDT

WASHINGTON (AP) - The nation's capital has prepared for emergencies with sleek communication systems, intelligence fusion centers and chemical detention centers at train stations.
 
What showed during the 5.8-magnitude quake that shook much of the East Coast on Tuesday was that evacuating during an emergency could tax the city's resources.
 
Traffic was snarled for miles in downtown Washington as employers released workers early at the same time thousands of commuters tried to drive home or cram onto buses and trains already overloaded and slowed by speed restrictions because of the quake.
 
A strong evacuation plan is seen as especially critical for Washington, the seat of federal government and a city perpetually on guard against terrorist attacks.