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8 PLANNING COMMISSIONERS JOURNAL / NUMBER 78 / SPRING 2010 environment, our health, and our eco- nomic vitality. As our anxiety about these problems grows, however, so does our creativity. We are in a time of fundamental change that portends both danger and oppor- tunity. and regional planners and decision-mak- ers to redesign existing and new places so that people can choose to walk, bike, or use transit for daily trips. Studies show that improving the proximity and connectivity of activities can reduce the overall number of vehicle trips generated within a given area by as much as 25 percent.2 This, along with operational improvements to improve free-flow move- ment on local roadways, can make an important contri- bution toward reducing the amount of CO2 generated. Stormwater runoff is another important environ- mental problem exacer- bated by our automobile- oriented development pat- tern. That’s because road- ways, surface parking lots, and driveways result in large amounts of paved, impervious sur- face which, in turn, can lead to excessive runoff. As the EPA’s Lynn Richards noted last year in an article in the Planning Commis- sioners Journal, it is important to ask whether street and road widths in our communities are sized appropriately since “over[ly] wide streets will create excess impervious cover.”3 Richards also touched on the importance of downsiz- ing our parking requirements, pointing out that “parking lots designed for peak demand periods [create] acres of unused pavement during the rest of the year.” FORWARD MOTION 21st Century Transportation Planning Challenges by Hannah Twaddell American settlement patterns have always been strongly in- fluenced by our transportation technology. In 18th century America, the best locations for cities and commerce were accessible to major rivers and ports. Few people lived in “backwater” com- munities. Once you got off the boat, however, you had to rely on the power of feet – human or horse. Within cities, all activities had to be located within walking distance of each other. Suburban growth extended about as far as one could go within a day’s ride from town. With the advent of steam- and diesel-powered trains in the 19th century, people began venturing away from the rivers and built new cities across the landscape. Howev- er, since foot-power was still the domi- nant form of local travel, rail towns retained the compact form of older com- munities. The automobile allowed us to spend the 20th century spreading out in all directions. Networks of highways and local roads created opportunities to build cities virtually anywhere. With the power of hundreds of horses under the hood, cars made it possible for people to live miles away from daily activities such as work, school, and shopping. No longer confined to the walkable dimensions of one-horse towns, we shaped new com- munities around large street networks and parking lots. As the 21st century dawns, the Amer- ican dream made possible by the remark- ably fast, flexible mobility of the automobile has begun to take on night- marish qualities. It is becoming clear that our collective dependence upon the automobile is threatening our natural “Giant Steamboats at New Orleans,” by Hippolyte Sebron (1853). 1 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007 (U.S. EPA, 2009). 2 Land Use and Site Design, Traveler Response to Transportation System Changes – TCRP-95 (Trans- portation Research Board, 2003). 3 “Managing Stormwater Runoff: A Green Infrastruc- ture Approach,” PCJ#73 (Winter 2009); available to order & download at: www.plannersweb.com/wfiles/ w284.html. Our Natural Environment A 2009 report by the U.S. Environ- mental Protection Agency indicates that fossil fuel combustion for transportation is responsible for a third of America’s CO2 emissions, which are an important ingre- dient of the “greenhouse gases” associat- ed with global climate change.1 The three most prominent factors affecting the transportation sector’s emis- sions are the fuel economy of vehicles on the road, the types of fuels used, and the overall amount of driving by all vehicles, expressed as vehicle miles traveled (VMT). Federal agencies, state governments, and private sector entrepreneurs are working on the tasks of making vehicles more energy-efficient and finding new sources of fuel. But our success at reduc- ing VMT depends largely upon our abili- ty to plan and locate communities in ways that reduce our need to drive. To achieve this goal, it is essential for local