Fall 2017 Issue

Research Exchange

Why Children Struggle to Cross Busy Streets Safely

New research from the University of Iowa shows that children under a certain age lack the perceptual judgement and motor skills to consistently cross busy streets without putting themselves in danger.

The researchers placed children ages 6 through 14 in a simulated, but realistic, environment and tasked them with crossing one lane of a busy road multiple times.

They found that crossing isn’t as seamless for children as is for adults. Accident rates were as high as 8 percent with 6-year-olds who participated in the simulation. The study found children could not navigate safely without incident until age 14, though 12 year-olds compensated for their inferior crossing skills by waiting to cross until there were larger gaps in traffic.

“Some people think younger children may be able to perform like adults when crossing the street,” said Jodie Plumert, a professor in the UI’s Department of Psychological and Brain Sciences who led the research team, in a news release about the study. “Our study shows that’s not necessarily the case on busy roads where traffic doesn’t stop.”

The National Center for Statistics and Analysis reported 8,000 injuries and 207 fatalities involving motor vehicles and pedestrians age 14 and younger in 2014.

Plumert’s team sought to understand the reasons behind the accident rates. For the study, they recruited children who were 6, 8, 10, 12, and 14 years old, as well as a control group of adults. Each participant faced a string of approaching virtual vehicles travelling 25 mph and then crossed a single lane of traffic. The time between vehicles ranged from two to five seconds. Each participant negotiated a road crossing 20 times, for about 2,000 total trips involving the age groups.

The crossings took place in an immersive, 3-D interactive space at the Hank Virtual Environments Lab on the University of Iowa’s campus. The simulated environment is “very compelling,” said Elizabeth O’Neal, a graduate student in psychological and brain sciences and the study’s first author, in the news release. “We often had kids reach out and try to touch the cars.”

The researchers found 6-year-olds were struck by vehicles 8 percent of the time; 8-year-olds were struck 6 percent; 10-year-olds were struck 5 percent; and 12-year-olds were struck 2 percent. Those age 14 and older had no accidents.

According to the study, children contend with two main variables when deciding whether it’s safe to cross. 

Younger children struggled to make consistently accurate perceptual decisions and timing their first steps to be able to cross before the oncoming traffic arrived.

 “Most kids choose similar size gaps (between the passing car and oncoming vehicle) as adults,” O’Neal says, “but they’re not able to time their movement into traffic as well as adults can.”

The researchers found children as young as 6 crossed the street as quickly as adults, eliminating crossing speed as a possible cause for pedestrian–vehicle collisions.

O’Neal recommends parents teach their children to be patient and teach younger children to choose gaps that are larger in order to cross safely. Planners can also help by identifying safe crossings or placing crossing guards at intersections.

 “If there are places where kids are highly likely to cross the road, because it’s the most efficient route to school, for example, and traffic doesn’t stop there, it would be wise to have crosswalks,” Plumert said.

—Jodie Plumert, Elizabeth O’Neal, Yuanyuan Jiang, Luke Franzen, Pooya Rahimian, Joseph Kearney and Paul Yon, University of Iowa

Equitable Bike Share Means Building Better Places for People to Ride


Bicycling is on the rise, but the risk of death and injury for people who bike is on the decline in major cities across the United States. Yet, the positive feedback loop between protected bike networks, bike share, bike safety and ridership is largely unexplored. 

This led the National Association of City Transportation Officials (NACTO) to analyze the relationship between these things across seven major cities to provide a deeper understanding of the trends and equity implications of decreasing risk and increasing bicycling.

Increasing safety when it comes to biking has significant implications for people of color as well as those who are low-income. Nearly half the people who bike to work—49 percent—earn less than $25,000 per year and biking at least once a year for black Americans increased by 90 percent from 2001 to 2009. Yet, black and Hispanic riders have a fatality rate 30 percent and 23 percent higher than white cyclists, according to the study. This is because minority and low-income neighborhoods are often dislocated from key destinations and employment opportunities and have poorer infrastructure for biking and walking, the study found.

Therefore, safety gains and understanding how to encourage them, are central to increasing equity for these groups.

NACTO researchers studied the relationship between bike network mileage, the number of cyclists killed or severely injured and bicycle volume in seven major cities across the United States and found in all cases the growth in cycling outpaced the rate of injuries or fatalities, and as ridership increased, risk decreased. 

In part these trends are due to “strength in numbers,” where motorists are more likely to be aware of cyclists and even pedestrians due to a greater volume of bike riders on streets. Another large part is the presence of bike infrastructure, with protected bike lanes serving to encourage the greatest number of potential bike riders overall, but particularly bike share participants, minorities and women who all gave a stated preference for biking in protected lanes. Bike count data and bike share trip origination data also bore out these preferences, with marked increases following the addition of lanes and a greater number of trip origination at stations near protected lanes.

On top of bike share systems supported by bike lane networks and particularly higher quality protected bike lanes, the researchers found a number of additional factors that contribute to increased safety and ridership. Among these were establishing a strong and long-lasting community relationship to guide projects, placing bike share stations such that they contribute to pedestrian and cyclist safety, removing mandatory helmet laws for adults, which decrease ridership and safety overall, and continuing to measure ridership and rates of injury and death.

The full report can be obtained at nacto.org 
Ranking Walkable Urbanism in America's Largest Metropolitan Areas

Walkable communities not only attract residents and visitors, but they also drive economic development according to a study by researchers at George Washington University.

The study, “Foot Traffic Ahead,” released by Smart Growth America and The Center for Real Estate and Urban Analysis at George Washington University’s School of Business, looked at 619 regionally significant, walkable urban places in the 30 largest metropolitan areas in the United State. The 30 metropolitan areas were ranked based on their walkable office, retail and multi-family rental space and the percentage of that square footage was occupied.

The researchers found that office and multi-family rentals increased in all 30 metropolitan areas from 2010 to 2015, while it decreased in drivable suburban markets. Of the 30 metropolitan areas, 27 saw their growth double during that time period.

Among the top-ranked metropolitan areas are New York, Washington, D.C., Boston, Chicago, San Francisco Bay and Seattle. All are densely populated cities, with significant economic investment and extensive transit systems. 

The researchers also found correlations between walkability and a highly educated work force and higher GDP per capita. The study however does not explore whether walkability encourages highly educated people to stay in an urban area, or whether these areas become more walkable because of their highly educated populations. 

The study considers social equity, but says more research is needed to better understand the role walkable urbanism plays in addressing equity challenges. 

While the researchers predict that these highly ranked metropolitan areas will continue to benefit from efforts to improve walkability, they note that the trend will depend on what lower ranked metro areas do. Will they continue to be car-centric or push for a more walkable community? The study predicts that Detroit, Phoenix, Los Angeles, St. Louis, Miami, Atlanta and Cleveland will accelerate their efforts to appeal more to people looking for walkability.

The full report can be found at: smartgrowthamerica.org/app/uploads/2016/06/foot-traffic-ahead-2016.pdf

—Researchers: Christopher B. Leinberger and Michael Rodriguez, The George Washington University School of Business
Empty Spaces: Real Parking Needs at Five TODs

When it comes to development of increasingly high-demand land near transit stations, the amount of parking is almost always determined by Institute of Transportation Engineer (ITE) guidelines that are based on isolated suburban land uses, not dense, and walkable places with public transit. 

In a first-of-its-kind study, researchers from the University of Utah analyzed vehicular trip generation and parking utilization at five transit-oriented developments (TODs) across the country. They found that even in TODs with less parking than recommended by ITE, parking was not used to capacity, and both generated trips and parking use were below ITE estimates. 

TOD attempts to maximize use of land in close proximity to public transit stations. This results in a mix of housing, offices, public services, and retail in an environment that accommodates a short and easy walk to and from these destinations and transit. Recent research indicates that such development is in high demand for home buyers and businesses.

Yet, despite this demand, the majority of zoning codes and parking requirements follow ITE Trip 
Generation and Parking Generation guidelines. 

The researchers selected and studied the five TODs—each with a single developer under a master development plan  in hopes of informing future TODs and allowing for more efficient use of highly valuable land. Gathering travel survey and parking use data at each site gave the researchers a picture of travel mode, parking location, and origin and destination.

Most striking among the study’s findings was that peak parking occupancy fell between 19 and 46 percent and this occurred with all five TODs supplying fewer than the ITE recommended parking spaces.

These findings are perhaps unsurprising given the walking and transit options available to reach these stations and the key destinations in close proximity to them. While the data provides evidence-backed guidance for future TODs—allowing for valuable land to be better and more efficiently utilized —it is important to note that due to cost constraints, the study areas were limited to smaller TODs, meaning they likely provide conservative estimates. 

The full report can be found at:  smartgrowthamerica.org/resources/empty-spaces-real-parking-needs-five-tods/

—Researchers: Reid Ewing, Guang Tian, and Torrey Lyons of the University of Utah’s College of Architecture + Planning, in partnership with Preston Stinger of Fehr & Peers Associates, and Rachel Weinberger, Ben Kaufman, and Kevin Shivley of Nelson\Nygaard Consulting Associate
Exploring the Association between Complete Streets Policies and Taking Public Transit to Work

Streets designs have historically focused on moving vehicles. Recently, there has been shift with greater adoption of complete streets policies, focusing on improving roadway design for all users—from people who bike and walk, to those who drive and take public transit. 

A study by a team of researchers from the University of Illinois at Chicago explored whether complete streets policies encouraged commuters to take public transit to work. The team found that commuters in cities and counties with policies in place were at least two times more likely to use transit than in places without policies.

Complete streets policies push planners and engineers to create and maintain streets safe for all users. This can include additional facilities, like sidewalks, bike lanes and bus stops. It can also include traffic calming measures, from pedestrian islands and curb extensions, to road diets that reduce lanes and lane widths to reclaim space for other modes. 

These efforts serve to increase safety and air quality and boost local economies as access is improved for alternative modes to key destinations like shopping and jobs. They also simultaneously promote health, by providing greater opportunity for physical activity in walking and biking both generally and to public transit hubs. But to what extent do complete street policies influence mode choice? And at what level can they be effective?

To answer these questions, University of Illinois at Chicago researchers compiled a list of counties and cities with complete streets policies as of May 2015. The researchers then looked at transit ridership in the 649 municipalities, 67 counties and the 31 states with policies in place. This data was then linked with American Community Survey (ACS) 2014 5-year estimates on public transit use, and multivariate regression models were run controlling for population size, income, age, and the presence of a state-level complete streets policy. 

The results indicated that when it comes to cities, those with complete streets policies had public transit use rates of 11.3 percent as opposed to 5.2 percent in those without. Similarly, counties with complete streets policies had public transit use rates of 6.9 percent as opposed to 2.5 percent at those without. The researchers concluded that complete streets policies correlate to higher incidence of taking public transit to work at both the city and county level. Future research is needed to establish a causal link between complete streets policies and public transit use.

The full report can be found at:  www.ihrp.uic.edu/files/WorkTransitBrief-Nov2016.pdf

—Researchers: Emily Thurn, Julien Leider, Jamie Chriqui, The University of Illinois at Chicago