Research and practice show that compact, connected street networks can result in improved health and safety outcomes

By Chris Spahr
Urban planning and public health have a long history together as demonstrated by the famous story of Dr. John Snow who, in 1854, mapped the cholera deaths within a particular 10-day period on Broad Street in London. Through his spatial analysis, he traced the cholera epidemic to a water pump resulting in the removal of the pump handle.  However, planning decisions in the U.S. have been more about efficient automobile movement and personal space than public health outcomes over the past century.  For example, in the 1930s, the Federal Housing Administration pushed for tree-like street networks to replace more traditional organic and gridded designs, which were described as “monotonous, unsafe, and characterless.”

The Evolution of Community Design and Street Networks in the U.S. (Journal of Transport and Public Health)
Gridded Street Network <————————————————————–> Tree-Like Network

The Evolution of Community Design and Street Networks in the U.S.
(Journal of Transport and Public Health)

Wesley Marshall, Daniel Piatkowski, and Norman Garrick recently published an article in the Journal of Transport and Public Health. The study found that traditional gridded street designs, which foster high levels of density and connectivity, have a greater association with good health than tree-like networks with their low densities and poor connectivity. More specifically, neighborhoods with compact and connected street networks and fewer lanes on major roads are positively correlated with lower rates of obesity, diabetes, high blood pressure, heart disease, and asthma. This may indicate that people living in cities with compact and connected street networks and smaller streets are healthier because these types of designs prioritize the pedestrian over the automobile. Or it could be a result of healthier people self-selecting into cities and neighborhoods with certain characteristics. However, previous research by Marshall and Garrick showed that utilitarian active transportation is much more common in compact neighborhoods with high levels of street connectivity. Furthermore, planning literature increasingly demonstrates the links between compact, walkable, diverse neighborhoods and positive social relations, health outcomes, and safety.
A major challenge facing the U.S. is that the evolution of its street network has not only contributed to unhealthy lifestyles but also poor street safety. A recent report from the International Transport Forum shows that the U.S. is far behind its peer nations on street safety. The traffic fatality rate in the U.S. currently is 10.7 people per 100,000, or nearly four times higher than in the United Kingdom and almost double the rate in Canada. Traffic deaths have been declining in the U.S. but not nearly as quickly as in other countries. From 2000 to 2012, the U.S. reduced traffic death rates just 20 percent; whereas countries like Denmark, Spain, and Portugal reduced rates by 65 percent or more over the same time frame.
health outcomes graph
The poor safety performance of streets in the U.S. may be related to its approach to safety improvements, which often include seat belt laws, automobile technology improvements, and traffic easing measures through capacity expansion. Whereas in many European countries, which already benefit from higher densities and more connected street networks within cities, “Vision Zero” plans are in effect and include low urban speed limits, pedestrian zones, and protected bike lanes.
The U.S., where one-third of adults are obese, has the research and tools to address health and safety through better transportation infrastructure choices. With the U.S. population projected to grow by nearly 40 percent by 2050, policy makers will have the opportunity over the coming decades to reshape our transportation infrastructure to support healthier and safer neighborhoods.
Chris Spahr is a Graduate Assistant with SSTI.