The built environment may be defined as the part of the physical environment created by human actions—buildings and parks, roads and trails, neighborhoods and cities. This section illustrates the importance of the built environment by describing how land use and related transportation patterns that characterize an entire metropolitan area affect injuries, air quality, and physical activity patterns (Frumkin, 2003).
The built environment contributes to motor-vehicle-related morbidity and mortality among children by creating places that rely heavily on increasing driving time in cars and by developing certain kinds of roads that may be unusually hazardous for drivers, pedestrians, or both. Modern suburban roads may be especially dangerous. Major commercial thoroughfares and feeder roads that combine high speed, high traffic volume, and frequent “curb cuts” for drivers entering and exiting stores may pose a special hazard. In general, the prevention of injury by one-time structural changes, such as highway or automobile engineering, is more effective than actions that require repeated use, such as bicycle helmets (Layde et al., 2002).
The epidemiology of pedestrian injuries among children has been well studied and includes several factors that relate directly to the built environment: high traffic volume and speed, absence of play space, and possibly one-way streets (Pitt et al., 1990; Roberts et al., 1995; Schieber and Thompson, 1996; Rivara, 1999; Wazana et al., 2000; DiMaggio and Durkin, 2002). Large boulevards are riskier than residential streets (Kraus et al., 1996), and denser census tracts are safer than those with low density (Lightstone et al., 2001). However, the effect of residential density is complex (Rivara and Barber, 1985; Rao et al., 1997; Posner et al., 2002).
Across the country, the pattern seen for driver and passenger fatalities is repeated for pedestrian fatalities, with lower annual rates in denser cities (National Highway Traffic Safety Administration, 2001). Data from Atlanta show that as that city has sprawled in recent years, the pedestrian fatality rate increased even as the national rate declined slightly (Centers for Disease Control and Prevention, 1999a). The most dangerous stretches of road were those with multiple lanes, high speeds, no sidewalks, long distances between intersections or crosswalks, and roadways lined with large commercial establishments and apartment blocks (Centers for Disease Control and Prevention, 1999a).
Reviews of injury prevention from motor vehicles in children focus almost entirely on seat belts, car seats, air bags, and other engineering approaches or on law enforcement and education (Pitt et al., 1990; Durbin, 1999; Towner and Ward, 1998; Rivara and Aitken, 1998; Rivara, 1999). Primary prevention, in contrast, includes strategies for traffic calming (Roberts et al., 1994; Liabo et al., 2003)