Gridlock is a form of traffic congestion where continuous queues of vehicles block an entire network of intersecting streets, bringing traffic in all directions to a complete standstill. [1] The term originates from a situation possible in a grid plan 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 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.
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. [2]
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 (from game theory). [3] 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.
In New York City, drivers who "block the box" are subject to a moving violation that comes with a US$90.00 penalty. Mayor Michael Bloomberg, noting that the ten-minute ticketing process actually contributes to overall traffic congestion, has asked the New York State Legislature 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. [4]
In Virginia Beach, Virginia, roads around the oceanfront feature signs at every intersection stating "Don't Block the Box", and threatening a $200 fine.
In Austin, Texas, a "Don't Block the Box" initiative began in 2015. [5] [6] A similar program was piloted in San Antonio in 2017. [7]
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. [8]
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 or warning signs, or a better public transportation system. This type of system is used in Zurich, Switzerland. [9]
According to The New York Times , the word gridlock was coined in New York City in the early 1970s. [10] The word appeared in an IEEE publication in 1971 in a different context. [11] The first appearances of gridlock in newspapers occurred during the 1980 New York City transit strike. The word is attributed to Sam Schwartz, who was then the chief traffic engineer for the New York City Department of Transportation at the time of the strike. [12] Schwartz said the word gridlock was used internally in his department during the 1970s, perhaps as early as 1971. [13] 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". [14] 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". [15]
Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads/sidewalks) for travel and transportation.
A high-occupancy vehicle lane is a restricted traffic lane reserved for the exclusive use of vehicles with a driver and at least one passenger, including carpools, vanpools, and transit buses. These restrictions may be only imposed during peak travel times or may apply at all times. There are different types of lanes: temporary or permanent lanes with concrete barriers, two-directional or reversible lanes, and exclusive, concurrent, or contraflow lanes working in peak periods.
A traffic enforcement camera is a camera which may be mounted beside or over a road or installed in an enforcement vehicle to detect motoring offenses, including speeding, vehicles going through a red traffic light, vehicles going through a toll booth without paying, unauthorized use of a bus lane, or for recording vehicles inside a congestion charge area. It may be linked to an automated ticketing system.
Traffic engineering is a branch of civil engineering that uses engineering techniques to achieve the safe and efficient movement of people and goods on roadways. It focuses mainly on research for safe and efficient traffic flow, such as road geometry, sidewalks and crosswalks, cycling infrastructure, traffic signs, road surface markings and traffic lights. Traffic engineering deals with the functional part of transportation system, except the infrastructures provided.
Road pricing are direct charges levied for the use of roads, including road tolls, distance or time-based fees, congestion charges and charges designed to discourage the use of certain classes of vehicle, fuel sources or more polluting vehicles. These charges may be used primarily for revenue generation, usually for road infrastructure financing, or as a transportation demand management tool to reduce peak hour travel and the associated traffic congestion or other social and environmental negative externalities associated with road travel such as air pollution, greenhouse gas emissions, visual intrusion, noise pollution and road traffic collisions.
Congestion pricing or congestion charges is a system of surcharging users of public goods that are subject to congestion through excess demand, such as through higher peak charges for use of bus services, electricity, metros, railways, telephones, and road pricing to reduce traffic congestion; airlines and shipping companies may be charged higher fees for slots at airports and through canals at busy times. Advocates claim this pricing strategy regulates demand, making it possible to manage congestion without increasing supply.
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, resulting in many of the roads becoming obsolete. When traffic demand is great enough that the interaction between vehicles slows the traffic stream, this results in congestion. While congestion is a possibility for any mode of transportation, this article will focus on automobile congestion on public roads.
Electronic toll collection (ETC) is a wireless system to automatically collect the usage fee or toll charged to vehicles using toll roads, HOV lanes, toll bridges, and toll tunnels. It is a faster alternative which is replacing toll booths, where vehicles must stop and the driver manually pays the toll with cash or a card. In most systems, vehicles using the system are equipped with an automated radio transponder device. When the vehicle passes a roadside toll reader device, a radio signal from the reader triggers the transponder, which transmits back an identifying number which registers the vehicle's use of the road, and an electronic payment system charges the user the toll.
A curb extension is a traffic calming measure which widens the sidewalk for a short distance. This reduces the crossing distance and allows pedestrians and drivers to see each other when parked vehicles would otherwise block visibility. The practice of banning car parking near intersections is referred to as daylighting the intersection.
A parking lot or car park, also known as a car lot, is a cleared area intended for parking vehicles. The term usually refers to an area dedicated only for parking, with a durable or semi-durable surface. In most jurisdictions where cars are the dominant mode of transportation, parking lots are a major feature of cities and suburban areas. Shopping malls, sports stadiums, and other similar venues often have immense parking lots.
Open road tolling (ORT), also called all-electronic tolling, cashless tolling, or free-flow tolling, is the collection of tolls on toll roads without the use of toll booths. An electronic toll collection system is usually used instead. The major advantage to ORT is that users are able to drive through the toll plaza at highway speeds without having to slow down to pay the toll. In some installations, ORT may also reduce congestion at the plazas by allowing more vehicles per hour/per lane.
Samuel I. Schwartz, also known as Gridlock Sam, is an American transportation engineer, formerly the New York City Traffic Commissioner, notable for popularizing the phrase "gridlock".
In New York City, a planned congestion pricing project would charge vehicles traveling into or within the central business district of Manhattan. This disincentivizing fee, intended to cut down on traffic congestion and pollution, was first proposed in 2007 and included in the 2019 New York state government budget by the New York State Legislature. As of June 2024, New York governor Kathy Hochul had indefinitely postponed the congestion charge. If the plan goes into effect, tolls will be collected electronically and will vary depending on the time of day, type of vehicle, and whether a vehicle has an E-ZPass toll transponder. The Metropolitan Transportation Authority (MTA) estimates a profit of $15 billion should the plan be implemented, which it intends to invest into long-term transportation initiatives citywide.
Road space rationing, also known as alternate-day travel, driving restriction and no-drive days, is a travel demand management strategy aimed to reduce the negative externalities generated by urban air pollution or peak urban travel demand in excess of available supply or road capacity, through artificially restricting demand by rationing the scarce common good road capacity, especially during the peak periods or during peak pollution events. This objective is achieved by restricting traffic access into an urban cordon area, city center (CBD), or district based upon the last digits of the license number on pre-established days and during certain periods, usually, the peak hours.
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, and vehicles may not enter the area so marked unless their exit from the junction is clear, or they are intending to turn and are prevented from doing so by oncoming traffic, or other vehicles on the box waiting to turn.
The Ecopass program was a traffic pollution charge implemented in Milan, Italy, as an urban toll for some motorists traveling within a designated traffic restricted zone or ZTL, corresponding to the central Cerchia dei Bastioni area and encircling around 8.2 km2 (3.2 sq mi). The Ecopass was implemented as a one-year trial program on 2 January 2008, and later extended until 31 December 2009. A public consultation was planned to be conducted early in 2009 to decide if the charge becomes permanent. Subsequently, the charge-scheme was prolonged until 31 December 2011. Starting from 16 January 2012, a new scheme was introduced, converting it from a pollution-charge to a conventional congestion charge.
Terminology related to road transport—the transport of passengers or goods on paved routes between places—is diverse, with variation between dialects of English. There may also be regional differences within a single country, and some terms differ based on the side of the road traffic drives on. This glossary is an alphabetical listing of road transport terms.
The externalities of automobiles, similar to other economic externalities, represent the measurable costs imposed on those who do not own the vehicle, in contrast to the costs borne by the vehicle owner. These externalities include factors such as air pollution, noise, traffic congestion, and road maintenance costs, which affect the broader community and environment. Additionally, these externalities contribute to social injustice, as disadvantaged communities often bear a disproportionate share of these negative impacts. According to Harvard University, the main externalities of driving are local and global pollution, oil dependence, traffic congestion and traffic collisions; while according to a meta-study conducted by the Delft University these externalities are congestion and scarcity costs, accident costs, air pollution costs, noise costs, climate change costs, costs for nature and landscape, costs for water pollution, costs for soil pollution and costs of energy dependency.
According to a "Global Driver Satisfaction" survey conducted by the navigation app Waze in 2015, Metro Manila had the "worst traffic on Southeast Asia". Emerson Carlos, MMDA assistant general manager for operation has mentioned that in 2015, motor vehicle registrations in Metro Manila peaked at around 2.5 million.
Traffic lights – devices positioned at road intersections, pedestrian crossings and other locations – control flows of traffic with social norms and laws created by the state. Traffic signals have to convey messages to drivers in a short period of time about constantly-changing road rules.