Traffic management: An outlook
Section snippets
Context
Urbanization is accelerating: in 2013 22% of the world׳s population lived in cities with more than 1M people, up from 18% in 1990 (http://wdi.worldbank.org/table/3.12). There are 527 such cities today (www.citypopulation.de/world/Agglmoerations.html). The increase in the urban population is accompanied by an even faster growth in automobile ownership. World vehicle sales hit a record 82.8M, expected to reach 85M in 2014 and 100M in 2018. While China will account for a third of the new vehicles
Excess demand or poor traffic management
In its online publication “Describing the Congestion Problem (http://www.fhwa.dot.gov/congestion/describing_problem.htm)” the US Federal Highway Administration (FHWA) notes that “the process of congestion relief begins by understanding the problem,” and asserts that “highway congestion, very simply, is caused when traffic demand approaches or exceeds the available capacity of the highway system.” It also offers a different definition of congestion as ‘performance reduction”: “congestion …
Traffic control and demand management
Road traffic is controlled by intersection signals, freeway on-ramp metering signals, and variable message signs giving information about diversions, warnings of congestion ahead, and estimates of travel times along a few routes. The signal settings are determined by a closed-loop feedback system comprising a sensing system that measures traffic, algorithms that process the measurements to estimate the traffic state, and procedures for calculating the signal settings based on the state
Conclusion
The purpose of transportation management is to improve
- 1.
mobility through minimization of congestion;
- 2.
environment through fuel economy and lower emissions;
- 3.
safety by reducing human errors in driving on the road; and
- 4.
parking by reducing the number of idle vehicles.
To fight congestion one has to assess its severity and cause. As discussed in Section 1, at present such assessment is crude and untrustworthy. To estimate demand, delay and productivity of a traffic network, vehicle (and passenger) counts
Acknowledgments
This research was funded by the California Department of Transportation under the TOPL (Tools for Operations Planning) project.
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