Smart Congestion Relief - Comprehensive Analysis Of Traffic Congestion Costs ...

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Smart Congestion Relief
Comprehensive Analysis Of Traffic Congestion Costs and Congestion Reduction Benefits
24 March 2013

--> http://www.vtpi.org/cong_relief.pdf

...Traffic congestion refers to incremental delay and vehicle operating costs caused by interactions among vehicles, particularly as traffic volumes approach roadway capacity. Conventional planning tends to consider traffic congestion a major problem and congestion reduction an important planning objective. It uses various methods to evaluate congestion such as roadway level-of-service and monetized congestion costs.

These methods have significant weaknesses:

* They reflect mobility-based planning which assumes that mobility is an end in itself rather than a way to achieve accessibility. They tend to overlook impacts on other forms of access, such as the tendency of wider roads and faster vehicle traffic to degrade non-motorized conditions and stimulate sprawl.

* They measure congestion intensity rather than total congestion costs. This ignores congestion avoided when travelers shift mode or reduce total vehicle travel. The Travel Time Index even implies that congestion declines if uncongested vehicle travel increases.

* They exaggerate the monetized value of congestion by using unrealistic baseline speeds and travel time costs. Commonly-cited congestion cost estimates, such as those published by the Texas Transportation Institute, represent the higher range of congestion costs; more realistic estimates based on economic principles are much lower.

* They ignore or underestimate generated traffic and induced travel impacts, including increased downstream congestion, traffic accidents, energy consumption, pollution emissions, and dispersed development patterns.

* They often overlook alternative congestion reduction strategies, such as improvements to alternative modes, transport pricing reforms, and smart growth policies when evaluating potential solutions to congestion problems.

* They undervalue alternative congestion reduction strategies by ignoring their co-benefits.

These omissions and biases tend to exaggerate the benefits of roadway expansion and undervalue other transport system improvements, including improvement to alternative modes, transportation demand management strategies such as pricing reforms, and smart growth land use policies. More comprehensive analysis is needed to identify truly optimal policies and projects.

Excessive estimates of congestion costs and congestion reduction benefits tend to contradict other planning objectives: they favor motorists over non-motorists and reduce overall transport system efficiency ...