Given the high levels of chronic disease, including obesity, diabetes, and asthma, that we are facing as a country and that we spend a higher percent of our GDP on healthcare than any other country, it is imperative that we address the root causes of disease. While access to healthcare and genetics are important factors that determine our health status, there is a growing recognition that land use and transportation systems impact our personal behaviors related to health and directly and indirectly impact our health status even more. Transportation systems impact health in many ways, for example through impacts on injuries and fatalities, environmental quality (e.g., air quality and noise), physical activity, and income.
Lawrence Frank, Sarah Kavage, and Todd Litman prepared a recent report that addresses these impacts. Promoting Public Health Through Smart Growth (SmartGrowthBC) describes how we can build healthier communities through land use and transportation practices. The report explains how our built environment shapes out transportation choices, and in turn, human health. Highlighted are the following:
- Land uses – retail, office, residential, open space, and schools – should be integrated rather than separated from one another, so that people can easily accomplish basic utilitarian needs on foot or bicycle.
- In the case of retail development, more small shops and services near to where people live will attract more walking trips than a few large shopping centers or a mall.
- Compact residential development puts more people within walking distance of parks, schools, transit, shops and services, and provides the vital market for those services.
- Streets and buildings that are built from a pedestrian perspective create places that are safe, vibrant and interesting for walkers, bicyclists, and transit users.
- Street and trail networks that are highly interconnected reduce the time and distance needed for pedestrians and cyclists to get from one place to another.
The authors also point out that in addition to helping create healthier communities, smart growth planning practices can help achieve other economic, social and environmental objectives for the community at large, such as:
- Reduced costs of providing public services and infrastructure on a per capita basis.
- Less air pollution and greenhouse gases created per person.
- The potential for offsetting transportation problems, such as traffic and parking congestion, accidents and exposure to pollution emissions.
- Increasing access to nearby destinations and independence for disadvantaged groups, people with disabilities, and elderly people.
- Increased convenience for caregivers and reduced cost of providing assistance to people with disabilities and the elderly.
- Providing opportunities for lower energy costs per capita.
- Stimulating community economic development.
- Increased design flexibility and new solutions to planning problems.
Health Impact Assessments
Over the past few years, Health Impact Assessments have been growing in acceptability and importance. While a traffic impact assessment focuses on the impact of the built environment on the transportation system, a health impact assessment focuses on the impact of both the built environment and the transportation system on:
- Injury
- Physical activity
- Air quality
- Access to healthy foods
Recent Pedestrian Safety Research
Statistical Evaluation of the Safety Effects of High-Visibility School (Yellow) Crosswalks in San Francisco
Fehr & Peers was retained by the San Francisco Municipal Transportation Agency (SFMTA) (through funding from the Metropolitan Transportation Commission’s Traffic Engineering Technical Assistance Program (TETAP)) to conduct a statistical analysis of the safety effects of high visibility school (yellow) crosswalks in the City. Documenting the empirical benefit of high visibility crosswalks was important to San Francisco because the SFMTA has been under increasing pressure to use high-visibility crosswalks at more non-school locations. San Francisco’s current policy is to use high-visibility crosswalks at school crossings and at uncontrolled, midblock crossings – locations believed to benefit from additional warning of pedestrian activity. However, continental-style crosswalks are four times more expensive ($1700 per crosswalk) to install and maintain in San Francisco than standard crosswalks. Documenting a safety benefit could justify a change to existing crosswalk policies to expand the use of high-visibility crosswalks with the potential to benefit other vulnerable pedestrian groups and the general public. Conversely, if there is not a safety benefit, there is less justification to expand the use of high-visibility crosswalks, at least while available funding is constrained.
For this study Fehr & Peers used the Empirical Bayesian (EB) Method, currently the industry standard for before-and-after collision analysis, to perform tests on the efficacy of high-visibility school (yellow, continental-style) crosswalks in the City of San Francisco. Statistical analysis compared the number of collisions predicted for the after period had the enhanced crosswalks not been installed to the number of collisions observed. The analysis used data for 54 treated intersections with high-visibility crosswalks and 54 control intersections, each chosen for their geographical proximity to a treated intersection. Results from this analysis suggest a statistically significant reduction in collisions at the intersections with high-visibility crosswalks. The estimated reduction is 37 percent, with a 95% confidence interval ranging from 13 percent to 60 percent.
The study was presented at the 2010 Transportation Research Board (TRB) Annual Meeting and will be published later in 2010 in the Transportation Research Record.
New Meta-Analysis by Reid Ewing
The Built Environment and Traffic Safety: A Review of Empirical Evidence
Reid Ewing and Eric Dumbaugh
From the Sage abstract: The study reaches two conclusions counter to accepted transportation engineering theory. First, the traffic environments of dense urban areas appear to be safer than the lower-volume environments of the suburbs. The reason is that many fewer miles are driven on a per capita basis, and the driving that is done is at lower speeds that are less likely to produce fatal crashes. Second, at least in dense urban areas, less-“forgiving” design treatments—such as narrow lanes, traffic-calming measures, and street trees close to the roadway—appear to enhance a roadway’s safety performance when compared to more conventional roadway designs. The reason for this apparent anomaly may be that less-forgiving designs provide drivers with clear information on safe and appropriate operating speeds.
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