Good transportation planning requires a solid understanding of the fundamental conditions that causes trends. This article examines various demographic and economic trends that affect travel demand and the implications of these trends for transportation planning. Although motorized mobility grew tremendously during the 20th century, the factors that caused this growth are unlikely to continue. Per capital mileage and vehicle ownership will likely decline in developed countries, while demand for alternatives such as walking, ridesharing, telecommuting, delivery service and public transit are increasing. The growing elderly population and higher fuel prices will contribute to this shift in demand. Although total travel demand will continue to increase, the degree to which travel shifts to alternative modes will depend partly on policy and planning decisions.
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