Ritical Analysis of the Trends in Vehicle Miles Traveled (VMT) in the United States
Note to Students
While this is a technical question, technical knowledge is only one element of what the reviewers are trying to evaluate in examining your responses. More importantly, this is a thinking exercise. Researchers must possess not only excellent technical and analytical skills but also a strong ability to think critically and effectively regarding research problems to expand human knowledge and to address societal needs. The main purpose of this question is to evaluate your ability to think through a problem, identify the most important issues in the areas that you have selected, to propose reasonable solutions and to prioritize any necessary research to ensure that these, or other solutions, meet real-world needs. The evaluation of your responses will focus principally on the clarity of your thought processes regarding the overall problem and your ability to express these ideas in written form rather than specific technical details regarding a small part of the overall problem. Look at the a?big picturea? and give the question your best effort.
Background (Read this discussion, and respond to the following questions)
For most of the last century, the trends in both personal and total annual vehicle-miles-travelled (VMT) in the United States have been steadily upward with only minor interruptions for wars, recessions and fuel embargos or price shocks. These VMT trends were driven by increases in population, income and trade volumes along with improved infrastructure, urban migration, changes in the structure of cities and other factors. Over this period, much of transportation planning has been dedicated to making provisions to effectively deal with these VMT trends both now and in the future.
Recently, VMT has been stable or declining in the United States. While the proximate cause of these recent reductions has almost certainly been due to the combined effects of increasing motor fuel costs and the general effects of the economic slowdown, there is some reason to suspect that future increases in U.S. VMT may be small or actual decreases may occur well into the future. While speculative and largely unproven, the argument for stable or decreasing VMT trends is based on changes in several demographic, economic and technological factors that impact VMT. These factors include:
a? An Aging Population: Like most developed nations, the median age of the American population is continuing to increase. Household VMT tends to reach a maximum when children are in their teenage years and as the population ages these peak VMT producing households will likely decline as a proportion of the overall population. In particular, as the large a?baby-boomera? generation ages and retires its contribution to overall VMT will likely decrease over time.
a? Changes in the Nature of Work: Much has been written regarding the potential of computer and telecommunications technologies to reduce VMT. While these technologies have had limited impacts to date, the ubiquitous availability of these technologies will likely have an increasing impact on the time and location of employment in future years.
a? Changes in Manufacturing and Distribution: New manufacturing technologies, for example additive manufacturing (i.e. 3D printing) offers the potential to drastically reduce the cost advantages of centralized large-scale production. Highly decentralized manufacturing may have the impact of reducing transportation requirements for both raw materials and finished goods and radically change the spatial distribution of manufacturing employment.
a? Changes in the Cost of Driving: As fuel economy rises and alternatively fueled vehicles proliferate, it is likely that additional funding mechanisms will be required to maintain transportation infrastructure. Most proposals for such funding sources aim to tie revenues much more directly to VMT and/or Time-of-Use. Arguably, such fees may provide a much more direct incentive for individuals to reduce VMT than fuel and excise taxes. Likewise, fuel costs are likely to remain relatively high for the foreseeable future even without significant increases in motor fuel taxes providing another financial incentive to reduce VMT.
a? Changes in the Cost of Real Property: A side effect of the recent collapse in the housing market is to make the existing housing stock within cities much more affordable for those individuals with stable jobs and good credit ratings thus encouraging in-migration into cities. This potential reversal of suburban and exurban migration patterns could result in significant alterations of travel patterns and mode choice over the coming years.
a? Stabilization of Workforce Participation Rates: After several decades of increases, female workforce participation in the U.S. has become comparable to that of men. This makes significant future VMT increases due to this factor unlikely.
a? Other Factors: A range of other factors may also make contributions to reducing VMT. These include alternative vehicle technologies (e.g. Segway type vehicles), increased availability of transit modes, improved bicycle and pedestrian facilities, etc..
You are asked to evaluate the following questions in light of the above discussion.
a? How reasonable are the above arguments? What are the most important opposing factors that would drive a continued increase in VMT? Given both sets of factors, is the long-term trend of U.S. VMT increases likely to be stopped or reversed over the next decade? In supporting your arguments please be as quantitative as the current state-of-knowledge allows.
a? Are there other factors that may influence your argument? If so, what are these factors?
a? Based on your answers to the above questions, what are the most important research needs in this area and how should this research be conducted? Based on these needs, design a research program to address these most important needs. Your discussion should emphasize the methods and approaches to be used in this research as well as any needs for long-term data collection.