Civil engineers can take the lead in designing sustainable cities
Walking was the dominant mode of transportation in cities for centuries. That only changed with the advent of tracks for horse-drawn omnibuses in the early 19th century, which was shortly followed by self-propelled trolleys and trains. By the mid-20th century, the car had taken over as the prevailing transport mode in most American cities. But, I foresee a return to walking as more and more people (often young) move to city centers and eschew the driving habits of previous generations (see Figure 1). Let me share with you some statistics that, for someone in the business as long as I have been, are startling and welcoming.
Americans are driving less. According to the National Household Travel Survey (NHTS), per-capita U.S. vehicle travel use peaked in 2001 (see Figure 2). The same source reveals that total U.S. vehicle miles traveled (VMT) peaked in 2007, and total fuel consumption peaked in 2006. By 2010, it was about 10 percent below the long-term trend projections.
Fewer Americans are getting driver's licenses. Those younger than 40 accounted for 50 percent of drivers in 1983 and now account for less than 40 percent of drivers. Only 22 percent of licensed drivers today are younger than 30, a significant decrease from 33 percent in 1983. The portion of 19-year-olds with a driver's license fell from 92 percent in 1977 to 77 percent in 2008. Between 1983 and 2008, the percentage of 18-year-olds with driver's licenses fell from 80 percent to 65 percent, the percentage of 17-year-olds with driver's licenses decreased from 69 percent to 50 percent, and the percentage of 16-year-olds with driver's licenses decreased from 46 percent to 31 percent.
Meanwhile, bike trips for 16- to 34-year-olds jumped 24 percent between 2001 and 2009.
So are we civil engineers ready to redo our cities to reflect this growing trend toward walking and biking (see Figure 3)? I maintain that we have largely ignored walking and concentrated solely on constructing automobile-oriented residential and circulation patterns throughout the country. Even in New York City – the bastion of the hearty walker – we have sold an unsustainable bill of goods to the public.
An example I've used repeatedly is that the Brooklyn Bridge, when it was largely a rail and walking bridge, handled 430,000 people daily. In the 1940s, we "modernized" it by removing the rail; its daily person-carrying volume dropped to 180,000.
During my lifetime, the Verrazano-Narrows Bridge between Brooklyn and Staten Island was built with 12 car lanes but no bikeway, walkway, or transit right-of-way. As a teenager I was able to bike from Brooklyn to Staten Island by taking a ferry. Once the bridge opened, the ferry stopped running and driving was the only choice – here in transit-rich New York City.
Most of the Interstate System built in the last half-century had no provisions for walkers, bike riders, or transitways. The consequences of accommodating driving at the expense of walking are apparent in current obesity levels and traffic-congestion dilemmas.
When it comes to finding funding for infrastructure projects, the biggest competitor for tax dollars is going to be health costs – and these two needs compound each other: The average American spends more than 100 hours commuting to work each year, and each hour spent in a car per day is associated with a 6-percent increase in the likelihood of obesity. Between 1960 and 2005, the obesity rate among American adults rose from 13 percent to 35 percent, according to the Centers for Disease Control and Prevention (CDC). More than 15 percent of children and adolescents ages two to 19 years are obese, according to the 2009-2010 National Health and Nutrition Examination Survey. Physical inactivity costs an estimated $177 billion per year in medical costs, and accounts for 16 percent of all deaths in both men and women.
In terms of road congestion and its own costs, there are some other sobering figures: In 2010, road congestion caused 4.8 billion hours of travel delay, wasted 1.9 billion gallons of fuel, and resulted in total congestion costs of $115 billion in 439 U.S. urban areas.
The Congressional Budget Office predicts that the U.S. Highway Trust Fund, which helps fund the federal transportation budget, will reach zero by 2014. In 2011, highway "user fees" (gasoline and other direct auto taxes) paid only about half the cost of building and maintaining the nation's network of highways, roads, and streets.
The "fundamental law of highway congestion," suggested by Anthony Downs in 1962 and affirmed by Duranton and Turner's 2009 "Fundamental Law Of Road Congestion Evidence From U.S. Cities" concludes that VMT increases proportionally to roadway lane miles for interstate highways and slightly less rapidly for other types of roads. A new roadway diverts little traffic from other roads. Simply put, people drive more when they have more roads to drive on. Expanding roads potentially increases air pollution, noise pollution, collisions, and adverse health outcomes.
And yet, as a profession, we have continued to build more roads, wider roads, and faster roads while knowing full well we were running out of capacity and making transport systems less efficient.
Designing walkable communities
We know that walking is incredibly efficient. Nearly a third of all car trips taken in this country are a mile or less in length – the equivalent of at most a 20-minute walk. Trips less than two miles represent about 40 percent of all trips. Moving those trips out of cars and onto sidewalks would solve many of our transportation conundrums.
We engineers have the technical know-how to design and construct walkable communities. The methods are deceptively easy: Build good transit systems and integrate them into existing infrastructure. Design transportation systems with pedestrians in mind. Construct multiple, direct connections within dense, mixed-land use developments. Coordinate transit, walking, cycling, and automobile networks (see "Steps to a Walkable Community").
Steps to a Walkable Community
The guide contains tactics for building or rebuilding cities and suburbs in ways that encourage walking. The guide is about making walking in cities safer, and it provides traffic-engineering techniques to achieve that. Steps to a Walkable Community also describes methods of organizing advocacy to reach these goals.
This guide is not intended to be a comprehensive guide to every walk-friendly tactic, but rather a compilation of innovative, multidisciplinary tactics that can improve walking from a variety of different angles. These multidisciplinary tactics are grouped by approach: advocacy, policy, land use, design and engineering, encouragement and education, and enforcement. Almost every method included here has been successfully implemented in North America. Each tactic is then described in a standardized, easy-to-read format under the following headings: definition, benefits, considerations, appropriate contexts, guidance, professional consensus, treatment adoption, and case study (where needed).
Sam Schwartz Engineering and America Walks launched Walksteps.org, an interactive website, at the end of October. The website will help readers select among these tactics and other emerging ideas to create innovative strategies to improve walking in their communities.
The principles of context-sensitive design and livable streets, and smart growth land use policies all support walkable communities and pedestrian infrastructure. It's time for civil engineers to reassume a leadership role in planning for the future well-being of our cities, towns, and suburbs. We can do it by joining medical professionals and city planners in designing healthy, walkable communities.
Samuel I. Schwartz, P.E., F.ITE, is president and CEO of Sam Schwartz Engineering (SSE), a firm that specializes in transportation planning and engineering. He also writes a weekly column on traffic for The New York Daily News and blogs for Engineering News Record and the Public Broadcasting System (PBS). Schwartz was chief engineer/first deputy commissioner for the New York City Department of Transportation (NYC DOT) from 1986 to 1990, New York City's traffic commissioner from 1982 to 1986, and from 1971 to 1982 held several key positions within the NYC DOT.