Definition

• Gridlock is used to describe any condition where traffic movement is impossible. However, traffic backups are only truly gridlock when the blockage occurs at intersections and over multiple "grids" or block intersections. These blocked intersections make movement on any of the roads impossible.
  
  

Causes

• Gridlock often occurs during rush hour when most drivers are either getting to or leaving work. During rush hour or any other busy traffic period, one or more drivers may get stuck in an intersection. These stuck drivers will back up the traffic on both roads. As traffic builds up, other roads down the grid will begin to be blocked which in turn causes further traffic build up. Gridlock can often spiral outwards from one blocked intersection and get exponentially worse.
  
  

Control Methods

• Traffic engineers try to create efficient traffic systems to help avoid gridlock. For example, they will calculate what intersections may be a problem and try to create alternate routes for drivers. Careful programming of traffic lights can help regulate traffic efficiently. People who are concerned with gridlock can try to use public transportation, where available, such as buses and subways. However, buses can still fall victim to gridlocks and crowded subway systems can have their own version of gridlock.
  
  

Worst Gridlock Cities

• In 2007, Christopher Elliot, a travel columnist for the MSNBC website, reported that gridlock was the worst in New York, San Francisco, Seattle, Minneapolis and Miami. In his report, one New York motorist suffered a one hour delay on the George Washington bridge, a figure Elliot considered "...pretty average." A Texas study found that traffic delays cost San Francisco commuters $1,121 a year in wages, and Seattle commuters should double their expected travel time. A collapsed bridge in Minneapolis in 2007 worsened ita overtaxed traffic system, while Miami residents lost $903 per person in wages and fuel that year.
  
  

Other Uses

• Gridlock is also used to describe any situation that is "hopelessly standing still." For example, a "political gridlock" describes a stalemate where political parties cannot come to a common agreement. A "legal gridlock" can refer to a jury that cannot decide on the guilt or innocence of a defendant.