Editing Traffic congestion (section)

===Economic theories===
[[File:Trafficjamdelhi.jpg|thumb|India's [[economic development in India|economic growth]] has resulted in a massive increase in the number of private vehicles on its roads overwhelming the transport infrastructure. Shown here is a traffic jam in [[Delhi]].]]

Congested roads can be seen as an example of the [[tragedy of the commons]]. Because roads in most places are free at the point of usage, there is little financial incentive for drivers not to over-use them, up to the point where traffic collapses into a jam, when demand becomes limited by [[opportunity cost]]. [[Private highway|Privatization of highways]] and [[road pricing]] have both been proposed as measures that may reduce congestion through economic incentives and disincentives {{Citation needed|date=June 2022}}. Congestion can also happen due to non-recurring highway incidents, such as a [[car accident|crash]] or [[road works|roadworks]], which may reduce the road's capacity below normal levels.
[[File:Traffic jam in Haikou, Hainan, China 01.jpg|thumb|right|upright=0.9|[[Economic history of China (1949–present)|Rapid economic growth]] in China has resulted in a massive increase in the number of private vehicles in its major cities. Shown here is a traffic jam in downtown [[Haikou]], [[Hainan Province]], China.]]
Economist [[Anthony Downs]] argues that [[rush hour]] traffic congestion is inevitable because of the benefits of having a relatively [[Business hours|standard work day]] {{Citation needed|date=April 2016}}. In a [[capitalism|capitalist]] economy, goods can be allocated either by pricing (ability to pay) or by queueing (first-come first-served); congestion is an example of the latter. Instead of the traditional solution of making the "pipe" large enough to accommodate the total demand for peak-hour vehicle travel (a supply-side solution), either by widening roadways or increasing "flow pressure" via [[automated highway system]]s, Downs advocates greater use of [[road pricing]] to reduce congestion (a demand-side solution, effectively rationing demand), in turn putting the revenues generated therefrom into [[public transportation]] projects.

A 2011 study in ''[[The American Economic Review]]'' indicates that there may be a "fundamental law of road congestion." The researchers, from the [[University of Toronto]] and the [[London School of Economics]], analyzed data from the U.S. Highway Performance and Monitoring System for 1983, 1993 and 2003, as well as information on population, employment, geography, transit, and political factors. They determined that the number of vehicle-kilometers traveled (VKT) increases in direct proportion to the available lane-kilometers of roadways. The implication is that building new roads and widening existing ones only results in additional traffic that continues to rise until peak congestion returns to the previous level.<ref>{{cite web|url=http://journalistsresource.org/studies/environment/transportation/fundamental-law-road-congestion-evidence-u-s-cities/|title=Fundamental Law of Road Congestion: Evidence from U.S. Cities|publisher=journalistsresource.org|date=November 17, 2014|access-date=March 6, 2012|archive-date=February 21, 2012|archive-url=https://web.archive.org/web/20120221083322/http://journalistsresource.org/studies/environment/transportation/fundamental-law-road-congestion-evidence-u-s-cities/|url-status=live}}</ref><ref>{{cite journal | last1 = Duranton | first1 = Gilles | last2 = Turner | first2 = Matthew A. | year = 2011 | title = The Fundamental Law of Road Congestion: Evidence from U.S. Cities | url = http://www.nber.org/papers/w15376.pdf | journal = American Economic Review | volume = 101 | issue = 6 | pages = 2616–52 | doi = 10.1257/aer.101.6.2616 | access-date = September 23, 2019 | archive-date = October 13, 2019 | archive-url = https://web.archive.org/web/20191013030946/https://www.nber.org/papers/w15376.pdf | url-status = live }}</ref>