Prior to the installation of a movable median barrier in January 2015, they were demarcated by vertical yellow markers placed manually in sockets in the roadway.
Generally, traffic flows in one direction or another in such a configuration (or not at all); the carriageways are not "split" into two-lane roadways during non-rush periods.
This center lane can be used by emergency vehicles like police cars, ambulance, and fire trucks to avoid traffic traveling in either direction.
Drivers are not allowed to use the center lane of such a highway for passing slow-moving vehicles, except when funding or space constraints dictate use of it as a rush hour "travel lane" when traffic is largely asymmetric between a central business district and its suburbs.
U.S. Route 13 near the Greenville, North Carolina, city limits is a rare instance of a posted warning sign that states "do not pass in center lane".
British Columbia Nova Scotia Ontario Alberta Quebec Alabama Alaska Arizona California District of Columbia Florida Georgia Indiana Kentucky Maryland Michigan Nebraska New Jersey New York North Carolina Ohio Pennsylvania South Carolina Tennessee Texas Utah Virginia In shopping centres and metro stations there may be an odd number of escalators, with one or more escalators running in different directions in different time of a day.