Gridlock

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For other uses, see Gridlock (disambiguation).See also Box junction

Gridlock is a term describing an inability to move on a transport network. The term originates from a situation possible in a grid network where intersections are blocked, prohibiting vehicles from moving through the intersection or backing up to an upstream intersection. This is illustrated below on a network of one-way streets (the red cars are those causing the gridlock by stopping in the middle of the intersection).

Most jurisdictions have legislation prohibiting drivers from entering an intersection if they cannot clear it before the traffic light turns red. If drivers follow this rule of the road, gridlock will be prevented and traffic will only be slow in the direction that is actually congested.

Although gridlock is most accurately described by the above definition, the term is also widely used to refer to levels of high traffic congestion in general, whether or not actual gridlock occurs.

[edit] Reasons for the problem

Gridlock, like many longstanding traffic problems, reflects that certain drivers who have an economic stake in getting to their destinations as quickly as possible, in a weak enforcement setting, are willing to subject other drivers to delays in order to attempt to secure a time-benefit for themselves, even if this is only illusory. The paradoxical aspect of this is, by contributing to the gridlock problem, these drivers are, en masse, actually slowing everyone down. This can be considered as a real-life example of the prisoner's dilemma.

Because of the schedule/money aspects of the problem, common gridlock violators in many urban areas in the United States are taxicabs and buses; buses run on a schedule and drivers sometimes cut corners on traffic rules to attempt to make their stops. Taxicabs participating in causing gridlock may represent more of a psychological problem; many taxi drivers work twelve hour shifts driving through cities, and know firsthand how common gridlock is. Faced with these conditions, the average taxi driver is likely to eventually become inured to gridlock, and therefore see nothing wrong with participating in it.

[edit] Etymology

There is a claim the word "gridlock" was coined by employees of the New York City Department of Transportation and popularized by transportation engineer and consultant Sam Schwartz [1], though there is some evidence the word appeared much earlier than 1980, another reference [2] has it coined in 1971. A Nexis search however turns up no newspaper references to the word prior to 1980.

The word ‘Gridlock’ entered the American lexicon in 1966. It owes its origins to the New York City transit strike of that year; where the intersections of Manhattan became so jammed with cars, that traffic on the entire island became hopelessly paralyzed.

To alleviate the crisis, Mayor Lindsey took the extraordinary step of closing Manhattan island to all incoming traffic; and devoting all lanes on Hudson and East River crossings to outbound traffic only.

There have been two transit strikes since then, but strict traffic control and vehicle occupancy rules have prevented a similar calamity.