During the past four decades, the obesity rate for children ages 6 to 11 has more than
quadrupled (from 4.2% to 17%), and it has more than tripled for adolescents ages 12 to 19
(from 4.6% to 17.6%).1, 2 Regular physical activity can reduce the risk for obesity and help
people lead longer, healthier lives. Yet studies show that less than half of U.S. children and
adolescents meet the recommended guidelines of at least 60 minutes of daily moderateto-
vigorous physical activity.3–5 The same studies indicate that less than 10 percent of adults
in the U.S. get the recommended 30 minutes of moderate-to-vigorous physical activity
per day.6–8
Walking and bicycling for daily transportation are important sources of physical
activity, but they have declined dramatically over the past few decades. Between 1977
and 1995,a the number of all walking trips decreased by 32 percent, and there was a similar
decrease in trips made by adults walking to work.9 Adults walk for only 21.2 percent of
trips that are one mile or less, and children walk for only 35.9 percent of trips to school
that distance.10 Reversing the decline in rates of walking and biking for transportation,
especially for short trips, presents a major opportunity for improving health among
children, adolescents and adults.
Transportation investments can either support or impede walking and bicycling in
neighborhoods and near schools, depending on how they are implemented. Evidence
is accumulating about how infrastructure improvements, programs that aim to manage
neighborhood road traffic, and efforts to make streets and sidewalks safer for active travel
influence travel patterns among both children and adults. This research brief presents
an overview of findings demonstrating the potential impact of infrastructure investments
and other transportation programs on walking and bicycling for transportation, and on
related health outcomes. It focuses on public transit, greenways and trails, school-related
infrastructure and programs, pedestrian and bicycle facilities, and efforts to manage
car traffic.
Key Research Results
* People who used public transportation (i.e. subways, commuter rails, light rails, buses, trolleys,
etc.) for any reason were less likely to be sedentary or obese than adults who did not use public
transportation.11–13 Nationwide, 29 percent of those who use transit were physically active for
30 minutes or more each day, solely by walking to and from public transit stops.14 Similarly, transit
users took 30 percent more steps per day and spent 8.3 more minutes walking per day than
did people who relied on cars.15 Conversely, reliance on the automobile for travel was associated
with higher obesity rates at both the county16 and individual level.17–20
* With few exceptions,21 proximity to public transit stops was linked to higher transit use and higher
levels of physical activity among adults.22–26 A study conducted in Salt Lake City, Utah, found
that 18.8 percent more residents used the rail system after a new rail stop opened in their area.27
* The physical activity associated with transit use saves money. According to one study of obesityrelated
medical costs, the extra walking related to transit use was estimated at a lifetime savings
of $5,500 per person in 2007 dollars.28 When accounting for decreases in quality of life, such as
disabilities
related to obesity, the estimated savings were even higher.29,30
* Most studies of children and adolescents indicate that walking or bicycling to school is related to
higher overall physical activity.32 However, the percentage of school-age children nationwide who
commute to school by walking or bicycling decreased by 68 percent from 1969 to 2001.33, 34
* Parents’ perceptions of the transportation route between home and school were among the
key factors determining whether children walk or bike to school.35, 36 Perceived safety from traffic
and crime have been associated with higher rates of children walking and bicycling to school.37, 38
A survey in Melbourne, Australia, found that children ages 5 to 6 and ages 10 to 12 whose parents
believed they had to cross several roads to get to play areas were between 40 percent and
60 percent less likely than other children to walk or bicycle to school or parks at least three times
per week.39
* Promotional and educational programs helped increase rates of biking and walking to school.40–42
Parental safety concerns about traffic tend to be a common obstacle to biking and walking to
school,43–45 but addressing safety behaviors and concerns through educational programs appears
to be a promising strategy. For example, US Walk to School programs have been associated
with higher walking rates.46 Additionally, the WalkSafe program, an educational injury-prevention
program
in Miami-Dade County, Fla., has led to children who are more likely to engage in safe
pedestrian behaviors (e.g., stopping and looking when crossing the street) or avoid unsafe
behaviors
(e.g., mid-street crossing and darting out) than were those who did not participate,
a change which was sustained over time.47
* Efforts promoted by programs such as Safe Routes to School, including building sidewalks, crosswalks
and traffic-control devices around schools, have been linked to both increases in the
percentage of students who walked to school48–52 and reductions in the percentage of students
being driven to school.53 Up to 39 percent of the land in large U.S. urban areas is within one-half
mile of a public school, so physical improvements in neighborhoods surrounding schools provide
safer walking environments not just to students, but also to residents in the surrounding
neighborhoods.54
* More and better-quality sidewalks are associated with adults having both higher rates of walking
and of meeting physical activity recommendations,56–61 and with a lower likelihood of being
overweight.62–64 Similarly, the presence of bicycle lanes and paths is positively related to cycling,65
and to more adults meeting physical activity recommendations.66–70 Cities that invest in bicycle
facilities exhibit higher levels of bicycle commuting.71
* A survey of more than 11,500 participants in 11 countries found that residents of neighborhoods
with sidewalks on most streets were 47 percent more likely to get moderate-to-vigorous physical
activity at least five days per week for at least 30 minutes each day than were residents of
neighborhoods
with sidewalks on few or no streets.72 A review of 16 studies found that people
who reported having access to sidewalks were 20 percent more likely to be physically active
than those reporting no access to sidewalks.73
* One study of cities across the country estimated that, for every 1 percent increase in the length
of on-street bicycle lanes, there was a 0.31 percent increase in bicycle commuters.74 Studies
conducted in Minneapolis, Minn., and Portland, Ore., showed that bicyclists were willing to go
farther than they would normally in order to use safe bicycle infrastructure.75–77
* Two studies found that facilities for bicycle parking, personal showering and locker storage at
destinations were a promising strategy for promoting cycling and walking.78, 79 The monetary
value of the benefits of having destinations with facilities to support walkers and bicyclists was
calculated at between $0.96 and $1.92 per bicycle trip.b
* Building multi-use trails can lead to short- and long-term increases in walking and cycling,
especially
on urban-area trails and trails that connect population centers with desirable
destinations,
such as downtowns.81–83 Furthermore, trails have been shown to be particularly
beneficial
in promoting physical activity among women and people in lower-income areas.84
* With few exceptions,85 living near trails or having trails in one’s neighborhood has been associated
with people being 50 percent more likely to meet physical activity guidelines86, 87 and 73 percent to
80 percent more likely to bicycle.88 In a nationally representative study, individuals who reported
using trails at least once per week were twice as likely to meet physical activity recommendations
as were those who reported using trails rarely or never.89 In a sample of pre-adolescent girls,
proximity
to trails was related to 4.8 percent more physical activity and a 1.4 percent lower body
mass index.90
* The financial gain of the health benefits related to trail use outweighed the cost of building and
operating the trails.91, 92 For example, in Lincoln, Neb., every $1 invested in trails was estimated to
save $2.94 in direct medical costs from a societal perspective.93
* Fast and heavy traffic is commonly cited by youth and adults as a barrier to walking and cycling.94–98
Infrastructure changes that decrease vehicle speeds, increase the attention of drivers and enhance
pedestrian safety are known as traffic-calming devices. Devices such as speed bumps and
visibility
aids can improve pedestrian and bicyclist safety. Other devices, including reductions in the
number or width of car lanes, sidewalk extensions into traffic lanes at street crossings, and space
for cars to park along the roadway, can help pedestrians but may be detrimental for bicyclists.
* Several recent reviews have examined how traffic-calming influences the risk of crashes involving
pedestrians, and that of automobile crashes resulting in injuries. One found that traffic-calming
substantially reduced the risk of crashes involving pedestrians,99 while another did not detect
reductions
in crashes involving pedestrians after such changes.100 The second of these reviews,
along with a third one, suggested that traffic-calming efforts resulted in 11 percent to 15 percent
lower rates of automobile crashes with injuries.101, 102 Traffic calming on residential streets may
have a greater effect than doing so on main streets.103
* With few exceptions,104 high levels of vehicular traffic have been associated with lower rates of
physical
activity in nearby areas.105, 106 Accordingly, some of the benefits of traffic calming included
increased walking and cycling, and enhanced opportunities for outdoor play among children
and adolescents.107–111 In one study, the number of observed pedestrians increased after the
introduction
of neighborhood traffic calming, and 20 percent of respondents reported they
walked more in the area as a result of the calming effort.112
Conclusion
* A substantial body of research shows that certain aspects of the transportation
infrastructure—public transit, greenways and trails, sidewalks and safe street
crossings near schools, bicycle paths, traffic–calming devices, and sidewalks that
connect schools and homes to destinations—are associated with more walking
and bicycling, greater physical activity and lower obesity rates.
* Beyond improving local travel options, transportation infrastructure investments
that support physical activity can result in increased recreational opportunities,
improvements to individuals’ health and decreased health care costs.
* In combination with infrastructure investments, programs that raise awareness
and complement pedestrian and bicycle facilities are promising options for
supporting physical activity. Specifically, Safe Routes to School programs and
the management of traffic in local neighborhoods and around schools have
been shown to affect physical activity among children, adolescents and adults.
* Fast vehicle traffic is a significant barrier and danger to bicyclists and pedestrians.
Measures to slow down traffic and to help pedestrians negotiate busy streets
can be effective in increasing physical activity and improving safety.
* Addressing the decades–long decline in walking and bicycling for transportation
requires changing the physical characteristics of our communities. Federal, state
and local policies and funding that support the type of infrastructure investments
and programs identified in this brief can help slow and perhaps even reverse
this decline.
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