Transportation

Developing better alternatives to current transportation systems and technologies is critical to any sustainable development strategy. Globally, mobility services are responsible for more than 60 percent of world oil consumption. The International Energy Agency predicts that global oil consumption will increase from its 2007 level of about 83 million barrels per day to more than 106 million barrels per day in 2030. In addition, despite all of the talk in recent years about alternative fuels, petroleum-based products remain dominant, constituting 98 percent of all transport energy consumption in 2008.

Given the growing demand in carbon-based transportation services, the following questions will be critical to meeting the challenges of sustainability. What are the principal modes of transportation? How do environmental externalities vary among modes? What are some common factors that influence the economic, social, and environmental characteristics of transportation systems? Also, what strategies can be employed to develop more efficient and environmentally sustainable methods to move people, goods, and services from point A to point B?

There are many available alternative transportation choices, including:

• Human-powered: walking, biking
• Private vehicle: rented or owned
• For hire, single party: taxi or limousine
• Shared ride: carpool, vanpool
• Rubber-tired: public transit bus or trolley bus
• Rail transit: street cars/light rail, monorail, heavy rail, commuter rail
• Airborne: airplane, helicopter
• Waterborne: ferry or personal boat

Each mode varies widely in cost. Environmental economists use an inclusive concept called triple bottom line accounting to measure cost. Triple bottom line accounting integrates social and environmental externalities associated with economic activity into overall cost calculations. According to this standard, air travel and private vehicles are generally more costly, and high-occupancy ground and waterborne public transit are usually less costly. For instance, carbon dioxide emissions per person-kilometer traveled by subway can be up to 90 percent lower than those generated by private vehicle use. However, despite their negative attributes, private vehicles continue to be the most sought-after mode of transport. This is evidenced by the fact that global vehicle production hovers around 70 million units per year and continues to grow. [Page 409]Interestingly, China is poised to overtake the United States as the biggest national producer of vehicles. It is also the world's leader in use of the most energy-efficient mode of human-powered transportation (as measured by distance traveled per calorie used)—the trusty bicycle.

The term transportation system typically refers to how various transportation modes are deployed and connected to one another to provide efficient and safe movement of goods and people. What agents affect the evolution of transportation systems, and particularly motorized vehicle use? Common factors include

• economic structure and growth;
• spatial and demographic characteristics;
• technological change, resource availability, and public policy;
• consumption culture; and
• urban planning culture.

In general, economically wealthy countries exhibit higher per capita mobility requirements (kilometers traveled/year) than less wealthy ones. Wealthy economies generate more economic activity, which generates more demand for mobility. There is an especially strong correlation between per capita wealth and demand for private modes of transport. Economic wealth also generates social and cultural change, including higher citizen interest in freedom of movement and engagement in mobility-intensive leisure and social activities.

Spatial development characteristics heavily influence the evolution of transportation systems. Countries with more geographically dispersed, lower-density urban systems such as the United States, Canada, and Australia generate more per capita transport demand, and especially private vehicle use. Density also increases the financial cost of building and maintaining public transit systems relative to private automobile transportation (though public transport is almost always cheaper if environmental externalities are factored into the calculation). On the other side of the density spectrum, in Asian megacities such as Hong Kong or Tokyo, mass transit is the preferred choice for most residents.

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