Charlier: Walkable Streets

Urban form is critical

Steve Hawley, May 01, 09.

Tagged with transportation, urban planning, pedestrians, video, safety, complete streets, bicyclists, distinguished speaker series

DISTINGUISHED SPEAKER SERIES

UPDATE (7/30/09, 4:05 pm): Video now available below.

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Walking is a critical human function, and urban streets must be designed with pedestrians in mind, according to Jim Charlier, who spoke on April 29 as part of Houston Tomorrow’s Distinguished Speaker Series. Charlier is a transportation planner based in Boulder, CO, and he has conducted pedestrian studies for numerous cities around the country. Approximately 70 people attended his presentation.

Pedestrians and the City: Planning and Design for Humans (pdf, 14.8 mb)

The pedestrian defined

Charlier noted that humans, for almost all of their existence, were nomadic hunter-gatherers, and that our bodies are consequently designed to walk and run. The human body is meant to burn 2,000 to 3,000 calories every day, he said, but as Americans walk less and less, obesity rates have skyrocketed. He also said studies have shown that regimented exercise programs are no replacement for living an active lifestyle throughout the day.

Charlier asked how many people in the room walked or biked to school in their youth, and nearly everyone raised their hands. However, when asked how many had children who regularly walked or biked to school, just two people raised their hands. Charlier noted that walking trips have fallen sharply and obesity rates have skyrocketed in less than a generation.

The problem, Charlier said, is how we design our cities. “It’s really not pleasant or safe to walk in most cities,” he said, and as a result most people drive, despite the fact that 25 percent of all car trips cover distances of less than a mile.

(How walkable is your neighborhood? Visit walkscore.com to find out!)

Charlier identified four types of pedestrian activity: rambling, in which people go outside just to walk; utilitarian walking, in which they walk to work or to run errands; strolling/lingering, in which they walk with the intent of spending money, and promenading, in which people walk around as a social function and look at other people. Walking is not just a health issue, according to Charlier, but it is a natural social inclination.

Pedestrians and urban form

Charlier noted that ideal traffic networks, consisting of short block grids rather than long, winding roads, work best for pedestrians as well. Street crossings, he said, must be no further apart than about 500 feet, and must create a safe environment for pedestrians. Pedestrian speed ranges between two miles per hour (a slow walk) and fifteen miles per hour (a sprint).

Human bodies can withstand collisions at those speeds, Charlier noted, but fatality rates rise dramatically above that. A pedestrian hit by a car at 20 mph has a 95 percent chance of surviving, but that number drops to 55 percent at 30 mph and just 15 percent at 40 mph. The same numbers apply to bicyclists.

“You don’t improve safety by making streets faster,” he said, noting that the ongoing widening of Kirby Drive will increase speed and make the road more dangerous to pedestrians.

In some areas, particularly newer cities in the West that have extremely long blocks and few crosswalks, he said it is demonstrably safer to jaywalk than to cross at intersections, simply because there is so much car activity at those intersections. “If you don’t fix [street crossings],” he said, “you won’t have a walkable city.”

But crosswalks alone do not encourage pedestrian activity, and nor do sidewalks. According to Charlier, sidewalks and street crossings are typically placed as an afterthought, rather than being viewed as a central element of street design.

To generate pedestrian activity, Charlier said a street must meet several design characteristics. First, it must have highly complex, intricate “street walls” such as store facades and windows. “You cannot have blank walls and have a pedestrian environment,” he stated.

Second, street scale is important. The ideal height-to-width ratio is 1:1, although pedestrians tolerate some variation. There are few 1:1 streets in North America, but there are large numbers in Europe, where many cities were built when walking was the prevalent form of transportation. Cities can also plant trees to create the illusion of scale, a tactic Charlier observed in some parts of Houston.

However, he also emphasized the need for flexibility. “Design should reflect the context of the [street],” he said. “What you do in an urban place is different from what you do in a suburban place,” but he said most cities design everything to suburban standards. He noted that the New Urbanist idea of urban transects - corridors with varying degrees of urban development - was a step in the right direction.

The pedestrian environment

“Pedestrian-friendly,” said Charlier, is just a catch phrase and does not necessarily mean anything. Instead, there is a distinct hierarchy of pedestrian zones. Most desirable is the pedestrian place or district, which includes mixed use and retail properties, has a distinct name and identity, is not dominated by vehicles, and has ready access to other forms of transportation. As a result, these areas have a significant pedestrian presence throughout the day.

Below that are pedestrian-supportive areas, which include identifiable places and mixed-use developments, and where pedestrians are present during certain times of day.

Pedestrian-tolerant areas include all other land uses except for freeways and special uses, such as airports and garbage dumps. These places may be used for utilitarian walking and rambling but do not support large numbers of pedestrians.

Finally, pedestrian-intolerant areas, such as freeways, support little to no walking, are unpleasant and unsafe to pedestrians, and are usually dominated by vehicles.

Charlier noted that pedestrian districts, pedestrian-supportive areas, and pedestrian-tolerant areas carry similar numbers of utilitarian pedestrians commuting or running errands, but that only pedestrian districts attract large numbers of people strolling and promenading. Outside of pedestrian districts, few people walk just for fun and enjoyment, even in pedestrian-supportive areas.

Pedestrian policy

Charlier said cities must use “level of service” in pedestrian planning, meaning that officials must use some form of objective evaluation. Properly-designed pedestrian zones, he said, will benefit landowners and businesses by driving up property values and increasing sales, although he said most landowners will initially fight such efforts, unaware of the benefits.

He also noted that cities must be able to prioritize. Not every part of a city can be pedestrian-friendly, he said, and planners must realize that pedestrian malls are nodes within an existing network, requiring adequate vehicle and transit service. Two-thirds of all North American pedestrian malls created in the last 50 years have failed and been removed as a result of poor planning.

Charlier also said that Houston is not unique in its lack of pedestrian access, comparing it to cities such as Phoenix and Los Angeles, although he said that Los Angeles was further along in the process than Houston. All young cities want to grow, he said, and only once the city realizes its flaws will it reinvest in existing areas. Houston might even be a model for the future, he said, as a polycentric or “honeycomb” city with several distinct high-density activity centers, including downtown, the Medical Center, Greenway Plaza, the Galleria, and Greenspoint.

Those centers could be made walkable and connected by transit, as METRO hopes to do with its 2012 light rail expansion. However, Charlier warned, “You can’t have a transit city before you have a walking city.”

The City of Houston Planning Commission is considering an urban corridor ordinance and hopes to approve the ordinance this summer. One of its goals it to “facilitate the development over time of a built urban environment that is pedestrian- and transit-supportive.”

The next Distinguished Speaker will be Dr. Richard Jackson on the evening of Thursday, June 18. Jackson will talk about health and the urban form. The previous Distinguished Speaker was Peter Newman, who spoke in January about how to create resilient cities in the face of peak oil, climate change, and the current economic collapse.

Part 1