Contraflow lane reversal is the altering of the normal flow of traffic, typically on a controlled-access highway, to either aid in an emergency evacuation or, as part of routine maintenance activities, to facilitate widening or reconstruction of one of the highway's carriageways.
Hurricane evacuation route marking near the Texas Gulf Coast
Crossing gates at the interchange between Interstate 16 and Interstate 95, used to prevent westbound access to I-16 during contraflow, Pooler, GA
Contraflow lane reversal in operation on I-93 in Concord, New Hampshire after completion of a NASCAR race at New Hampshire Motor Speedway, looking south.
Emergency evacuation is an immediate egress or escape of people away from an area that contains an imminent threat, an ongoing threat or a hazard to lives or property.
Evacuees on Interstate 45 leaving Galveston, through Houston, during Hurricane Rita in 2005. Note how no south-bound lanes (right) were used as north contra-flow lanes for vehicles turning west.
An exit sign in the United States, showing the way to the nearest exit, with two emergency lights for electrical failure.
Operation guide metal plate for emergency exits installed in the school bus window.
Evacuation route sign on Tulane Avenue in New Orleans after Hurricane Katrina.
