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Gridlock is a form of
traffic congestion Traffic congestion is a condition in transport that is characterized by slower speeds, longer trip times, and increased vehicular queueing. Traffic congestion on urban road networks has increased substantially since the 1950s. When traffic de ...
where "continuous queues of vehicles block an entire network of intersecting streets, bringing traffic in all directions to a complete standstill". The term originates from a situation possible in a
grid plan In urban planning, the grid plan, grid street plan, or gridiron plan is a type of city plan in which streets run at right angles to each other, forming a grid. Two inherent characteristics of the grid plan, frequent intersections and orthogona ...
where intersections are blocked, preventing vehicles from either moving forwards through the intersection or backing up to an upstream intersection. The term ''Gridlock'' is also used incorrectly to describe high
traffic congestion Traffic congestion is a condition in transport that is characterized by slower speeds, longer trip times, and increased vehicular queueing. Traffic congestion on urban road networks has increased substantially since the 1950s. When traffic de ...
with minimal flow (which is simply a traffic jam), where a blocked grid system is not involved. By extension, the term has been applied to situations in other fields where flow is stalled by excess demand, or in which competing interests prevent progress.


Cause

Traditional gridlock is caused by cars entering an intersection on a green light without enough room on the other side of the intersection ''at the time of entering'' to go all the way through. This can lead to the car being trapped in the intersection when the light turns green in the other direction. If the same situation occurs simultaneously in multiple intersections, these cars can be trapped in the intersections indefinitely. In many jurisdictions, drivers are therefore prohibited from entering an intersection at a green light if there is no room for them to clear the intersection. If all drivers follow this rule, gridlock is impossible. Another type of gridlock can occur during traffic surges between highway on-ramps and off-ramps located within a quarter mile of each other. Traffic exiting the highway may back up and block the entering vehicles. Those entering vehicles in turn back up and block the exiting vehicles. Gridlock is sometimes cited as an example of the
prisoner's dilemma The Prisoner's Dilemma is an example of a game analyzed in game theory. It is also a thought experiment that challenges two completely rational agents to a dilemma: cooperate with their partner for mutual reward, or betray their partner ("defe ...
(from
game theory Game theory is the study of mathematical models of strategic interactions among rational agents. Myerson, Roger B. (1991). ''Game Theory: Analysis of Conflict,'' Harvard University Press, p.&nbs1 Chapter-preview links, ppvii–xi It has applic ...
). Mutual cooperation among drivers would give the maximum benefit (prevention of gridlock), but this may not happen because of the desire to maximize one's own benefit (shortest travel time) given the uncertainty about the other drivers' commitment to equal cooperation.


Enforcement


New York City

In
New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...
, drivers who " block the box" are subject to a moving violation that comes with a US$90.00 penalty. Mayor
Michael Bloomberg Michael Rubens Bloomberg (born February 14, 1942) is an American businessman, politician, philanthropist, and author. He is the majority owner, co-founder and CEO of Bloomberg L.P. He was Mayor of New York City from 2002 to 2013, and was a ca ...
, noting that the ten-minute ticketing process actually contributes to overall
traffic congestion Traffic congestion is a condition in transport that is characterized by slower speeds, longer trip times, and increased vehicular queueing. Traffic congestion on urban road networks has increased substantially since the 1950s. When traffic de ...
, has asked the
New York State Legislature The New York State Legislature consists of the two houses that act as the state legislature of the U.S. state of New York: The New York State Senate and the New York State Assembly. The Constitution of New York does not designate an official te ...
to remove “blocking the box” from the moving violation category. This reclassification would give more traffic agents authority to write tickets and change the current ticketing procedure, which requires that the issuing officer physically stop the violating car in traffic.


Virginia Beach, Virginia

In
Virginia Beach, Virginia Virginia Beach is an independent city located on the southeastern coast of the Commonwealth of Virginia in the United States. The population was 459,470 at the 2020 census. Although mostly suburban in character, it is the most populous city ...
, roads around the oceanfront feature signs at every intersection stating "Don't Block the Box", and threatening a $200 fine.


Texas

In Austin, Texas, a "Don't Block the Box" initiative began in 2015. A similar program was piloted in
San Antonio ("Cradle of Freedom") , image_map = , mapsize = 220px , map_caption = Interactive map of San Antonio , subdivision_type = Country , subdivision_name = United States , subdivision_type1= State , subdivision_name1 = Texas , subdivision_t ...
in 2017.


Effects

The obvious effects are driver frustration and trip delay. Another effect in cities is exacerbated by the presence of urban street canyons, which effectively trap air pollution and increase air pollution exposures of motorists as well as the general urban population. Noise pollution can be aggravated by excessive starting and stopping noise of gridlocked facilities.


Alleviating gridlock

To make a traffic system less susceptible to gridlock, a traffic metering system can be introduced. These systems determine the optimal number of vehicles allowed in a traffic system, and prevent any extra vehicles from entering. This can be done with traffic control devices, such as
traffic lights Traffic lights, traffic signals, or stoplights – known also as robots in South Africa are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control flows of traffic. Traffic lights ...
or warning signs, or a better public transportation system. This type of system is used in Zurich, Switzerland.


Etymology

According to ''
The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'', the word ''gridlock'' was coined in
New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...
in the early 1970s. The word appeared in an IEEE publication in 1971 in a different context. The first appearances of ''gridlock'' in newspapers occurred during the
1980 New York City transit strike A 1980 transit strike in New York City halted service on the New York City Transit Authority (a subsidiary of the Metropolitan Transportation Authority) for the first time since 1966. Around 33,000 members of Transport Workers Union (TWU) Local 10 ...
. The word is attributed to
Sam Schwartz Samuel I. Schwartz, a.k.a. Gridlock Sam, is an American transportation engineer, formerly the New York City Traffic Commissioner, notable for popularizing the phrase " gridlock". Life and career Schartz was educated at Brooklyn College (BS Physi ...
, who was then the chief traffic engineer for the
New York City Department of Transportation The New York City Department of Transportation (NYCDOT) is the agency of the government of New York City responsible for the management of much of New York City's transportation infrastructure. Ydanis Rodriguez is the Commissioner of the Depart ...
at the time of the strike. Schwartz said the word ''gridlock'' was used internally in his department during the 1970s, perhaps as early as 1971. Writing up a memo of emergency recommendations for senior officials, he recalled the words of a colleague several years earlier who had been analyzing a proposal to close Broadway to vehicular traffic. His colleague gave the plan the thumbs-down, worrying that it would simply "lock up the grid". Schwartz was always struck by that image and titled his 1980 memo "Gridlock Prevention Plan". In another interview Mr. Schwartz said that he coined the term in the mid 1970s with fellow traffic engineer, Roy Cottam, who "was a little paranoid and thought he would be blamed for gridlock and so he gave me all the credit".


Historical events


China

The August 2010 traffic jam in the
Beijing } Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 2 ...
-
Zhangjiakou Zhangjiakou (; ; ) also known as Kalgan and by several other names, is a prefecture-level city in northwestern Hebei province in Northern China, bordering Beijing to the southeast, Inner Mongolia to the north and west, and Shanxi to the sout ...
highway in
Hebei Hebei or , (; alternately Hopeh) is a northern province of China. Hebei is China's sixth most populous province, with over 75 million people. Shijiazhuang is the capital city. The province is 96% Han Chinese, 3% Manchu, 0.8% Hui, and ...
province, China, is considered the world's worst traffic jam ever, as traffic congestion stretched more than from August 14 to the 26, including at least 11 days of total gridlock, with some drivers spending up to 5 days to cross this stretch of highway. The event was caused by a combination of road works and thousands of coal trucks from Inner Mongolia’s coalfields that travel daily to Beijing. The ''
New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'' has called this event the "Great Chinese Gridlock of 2010."


Brazil

According to ''
Time Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, t ...
'' magazine,
São Paulo São Paulo (, ; Portuguese for ' Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the Ga ...
has the world's worst daily traffic jams. On 23 May 2014, the worst traffic jam in history was registered, with of traffic jam.


France

For several years, the traffic jam that occurred in 1980 over a long stretch of the French
A6 Autoroute The A6, also known as the Autoroute du Soleil, ''Motorway of the Sun'', (along with the A7), is an Autoroute in France, linking Paris to Lyon. The motorway starts at Paris's Porte d'Orléans and Porte d'Italie with two branches, numbered A6a ...
between
Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...
and
Lyon Lyon,, ; Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the third-largest city and second-largest metropolitan area of France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of th ...
was considered the world’s longest.


See also

*
Box junction A box junction is a road traffic control measure designed to prevent congestion and gridlock at junctions. The surface of the junction is typically marked with a yellow criss-cross grid of diagonal painted lines (or only two lines crossing ea ...
*
Deadlock In concurrent computing, deadlock is any situation in which no member of some group of entities can proceed because each waits for another member, including itself, to take action, such as sending a message or, more commonly, releasing a l ...
- computer software analogy *'' Journal of Transport and Land Use'' * Roadway air dispersion modeling * Rush Hour (puzzle)


References

{{Reflist, 35em Road transport