Washington, D.C ? Authorities will rely on hundreds of thousands of people leaving the Fourth of July fireworks display on the National Mall to test the city’s emergency evacuation plan.

More than 500,000 people typically attend the fireworks show, and officials hope those who are directed along designated evacuation routes will get out of the city more quickly than usual. Pedestrians and subway riders also will be monitored.

City officials last year directed pedestrians and motorists leaving the Mall to evacuation routes. This year, officials also are working with traffic engineers and police in the surrounding areas of northern Virginia and suburban Maryland to determine how quickly 12 routes can move people out of the city.

Transportation officials are retiming 98 traffic signals in Washington in an effort to enable motorists who use the city’s busiest commuter routes to quickly move to the suburbs.