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This article describes how smart growth policies and mobility management programs can help create healthier and safer communities by reducing per capita automobile travel and increasing use of alternative modes, particularly walking and cycling. Transportation and land use planning decisions affect the amount and type of travel activity in a community and thus affect human health in several ways, including traffic risk, pollution emissions and by affecting physical activity and fitness. These impacts are each significant in magnitude, affecting large numbers of deaths and physical disabilities. Conventional planning tends to overlook and undervalue these impacts, consequently overlooking the benefits of smart growth policies and mobility management programs. Better evaluation of safety and health impacts tends to reduce emphasis on roadway capacity expansion and increase emphasis on smart growth and mobility management strategies. Integrating health objectives into transportation planning can be one of the most cost-effective ways to improve public safety and health and improved public health can be among the greatest benefits of smart growth and mobility management.
Cet article porte sur la maniere dont les politiques en matiere de croissance urbaine intelligente et les programmes de gestion des deplacements peuvent contribuer a creer des collectivites davantage en sante et en securite, en reduisant les deplacements automobiles par habitant et en augmentant I'utilisation d'autres modes transports, plus particulierement la marche et le velo. Les decisions en matiere de transport et d'amenagement territorial ont une incidence sur le volume et le type de deplacements dans une collectivite, ce qui a egalement une incidence sur la sante de ses habitants, notamment en ce qui a trait aux risques lies a la circulation automobile, a la pollution et a I'activite physique. Chacune de ces consequences est importante en soi, car toutes entrainent un grand nombre de deces et d'incapacites physiques. La planification conventionnelle a tendance a en faire abstraction et a les sous-estimer, et, par consequent a ne pas tenir compte des bienfaits des politiques de croissance intelligente et des programmes de gestion des deplacements. Une meilleure evaluation des consequences en matiere de securite et de sante permet generalement de mettre moins d'emphase sur I'augmentation de la capacite des routes et davantage sur des strategies de croissance intelligente et de gestion des deplacements. integration des objectifs de sante a la planification des transports peut se reveler l'une des manieres les plus rentables d'ameliorer la sante et la securite publiques, et une meilleure sante publique peut, ce son cote, compter parmi les avantages les plus importants de la croissance intelligente et de la gestion des deplacements.
Keywords
Transportation, planning, health, smart growth, mobility management
Introduction
Smart growth land use policies and mobility management transportation programs help create more compact, mixed communities, where residents drive less and rely more on alternative modes of transportation. These policies and programs can provide a variety of economic, social and environmental benefits, including improved public safety and health (Killingsworth 2003, Frumkin et al. 2004, SGN 2006; see also ALBD, online).
Conventional planning tends to overlook or undervalue many safety and health impacts, either because they are difficult to quantify or because they are considered outside the scope of conventional planning. As a result, public policies and development practices continue to build unhealthy and dangerous communities. Many families choose to live in automobile-dependent neighborhoods, unaware of the additional risks that result.
Described more positively, by changing planning practices and educating consumers it is possible to create healthier and safer communities in ways that are cost effective and beneficial overall. Smart growth development policies can be one of the most cost effective ways of improving public health and safety--and improved health and safety are often one of the most important benefits of smart growth.
This paper examines these issues. It discusses how transportation and land use factors affect public health, identifies current planning biases that undervalue health and safety impacts, and describes specific policy and planning strategies to help create healthier and safer communities. Since research in this area is still relatively new, I draw upon results from different regions and communities to illustrate the impacts and potential. Finer scale comparisons require more specific matching of community characteristics, however, the broader generalizations used here are helpful in understanding trends and for drawing attention to gaps in research and analysis. This paper should be useful to public health professionals and planners who want to incorporate safety and health objectives into community development.
Transportation Health Impacts
Transportation policy and planning decisions can have significant health impacts. Of the ten most common causes of death in the U.S., seven are affected by transportation (Figure 1). Figure 2 provides a similar comparison, showing how transportation affects the ten main causes of Years of Potential Life Lost (YPLL). This unit of measurement takes into account age at death, so traffic crashes rank higher because they tend to kill younger people than illnesses associated with sedentary lifestyles and pollution. These analyses indicate that transportation planning decisions impact public health in three main ways: through traffic crashes, vehicle pollution and physical activity (WHO 2000, Frank et al. 2006). Conventional decision-making tends to assign each of these issues to separate professions and agencies. For example, transportation engineers are responsible for reducing crash rates, environmental professionals explore ways to reduce pollution, while medical and recreation professionals promote physical fitness. This type of "reductionist" decision-making can result in solutions to one problem that tend to exacerbate other problems and tends to undervalue strategies that provide multiple but more modest benefits.
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For example, efforts to reduce motor vehicle crash rates by widening roadways and intersections and by limiting pedestrian crossing opportunities often degrade walking and cycling conditions, leading to more total vehicle travel and pollution emissions and reduced use of these transportation modes, which subsequently leads to less physical activity and fitness. Similarly, efforts to increase physical fitness by creating regional recreation centers and promoting organized team sports can result in more driving, which increases total air pollution and crash risk. On the other hand, improving neighborhood walking and cycling conditions and promoting the use of these modes as a substitute for driving contributes to reductions in traffic crashes, air pollution and sedentary living. However, these considerations often rank low in priority when experts evaluate potential solutions to each of these problems. The full value of transportation and land use policies that reduce total driving and encourage use of alternative modes only becomes evident when all of these health impacts are considered together.
The following sections describe and compare these major categories of transportation health impacts.
Evaluating Traffic Safety
It is important that transportation and health professionals understand how different ways of measuring traffic risk affect our thinking about this problem and our search for potential solutions. Conventional traffic safety analysis tends to evaluate risk in ways that ignore the risks resulting from increased motor vehicle travel and the safety benefits resulting from mobility management and smart growth strategies that reduce total vehicle travel. Only by applying more comprehensive analysis can transportation and health planners identify truly optimal safety strategies.
In addition, while traffic safety refers to minimum risk from traffic crashes, it leaves open the question of risk to whom? Just to the traveler using a particular vehicle or mode, or to all road users? How is this measured? Per unit of vehicle travel, or per capita? Consider, for example, the U.S. National Traffic Safety Administration rating of vehicles for crash protection, which shows that larger, heavier vehicles tend to offer occupants greater protection in crashes with other vehicles. We would likely conclude that choosing a larger, heavier vehicle with greater crash protection increases safety. However, this reflects a narrow perspective and can result in decisions that reduce overall safety (Chirinko and Harper 1993). The greater protection to occupants offered by larger, heavier vehicles with features such as airbags tends to be offset by other factors such as:
* Greater risk to other road users: Larger vehicles impose more risk to smaller vehicles, and automobiles impose more risk to pedestrians and cyclists.
* More intensive (riskier) driving.
* Increased exposure (i.e., more travelling).
* Increases in other types of risks: For example, sport utility vehicles and light trucks are vulnerable to rollover accidents and airbags impose risks to some vehicle occupants.
As a result, while increased vehicle crash protection is marketed to consumers as a way to increase their own safety, it may provide little or no increase in safety overall. Similarly, medical problems and crime tend to increase with poverty rates, and, since many dense, urban neighborhoods have high poverty rates, there is statistical evidence that cities are unhealthy and dangerous places. However, this does not mean that an individual who moves from a suburb to a city becomes unhealthy or endangered, or that policies that increase land use density increase crime. There is no evidence that the associations between density and illness or crime reflect causation (Lucy and Phillips 2006).
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