Driving and the Built Environment

Is there nothing we can learn from the past?  Why is the behavior of self-selectors so easily dismissed?  Why must the definition of mixed-use be so narrowly defined?  Is it unreasonable to believe that economic conditions stand to change greatly during a period of resource contraction?  These are some of the questions that repeated themselves in my mind as I read and analyzed the Transportation Research Board’s special report (http://onlinepubs.trb.org/Onlinepubs/sr/sr298.pdf) that attempted to definitively correlate compact development to a reduction in vehicular miles traveled, and by extension, to a reduction in energy consumption and emissions.

The quantity of vehicular miles traveled (VMT) in 1985 represents an approximate 40% decline from 2010 levels.  The ability to achieve such a reduction, or one even more significant, is dismissed by this study as nearly impossible, despite their inclination to find a large negative elasticity between the two factors.  While overtly recognizing the national development pattern as unsustainable (“…these dispersed, automobile-dependent development patterns have come at a cost, consuming vast quantities of undeveloped land; increasing the nation’s dependence on petroleum, particularly foreign imports; and increasing greenhouse gas emissions that contribute to global warming.”),  the board was unwilling to declare suburbanization a reversible trend.  They were also overly eager to dismiss self-selective behavior, presumably as an oddity or minority behavior, instead of recognizing its potential indicative qualities or its contribution to VMT decline.

Credit is due to the research council for tacking onto their mandate the question of determining density thresholds that would enhance transit feasibility.  Unfortunately they come to no conclusion after dismissing previous transportation studies as outdated and citing an inadequacy in the number and quality of studies related to non-motorized transportation.  Also unfortunate is the politicization inherent in the report’s representation of energy dependence as simply a cost/security issue.  While more palatable to the report’s direct intended audience, this does not respect the urgency related to potential resource unavailability as touched upon in the University of Utah Metropolitan Research Center’s response (http://www.smartgrowthamerica.org/documents/ResponsetoTRBSpecialReport.pdf).

The primary findings and recommendations of the report are as follows:

FINDINGS

1. Developing more compactly, that is, at higher residential and employment densities, is likely to reduce vehicle miles traveled (VMT).
2. The literature suggests that doubling residential density across a metropolitan area might lower household VMT by about 5 to 12 percent, and perhaps by as much as 25 percent, if coupled with higher employment concentrations, significant public transit improvements, mixed uses, and other supportive demand management measures.
3. More compact, mixed-use development can produce reductions in energy consumption and CO2 emissions both directly and indirectly.
4. Illustrative scenarios developed by the committee suggest that significant increases in more compact, mixed-use development will result in modest short-term reductions in energy consumption and CO2 emissions, but these reductions will grow over time.
5. Promoting more compact, mixed-use development on a large scale will require overcoming numerous obstacles. These obstacles include the traditional reluctance of many local governments to zone for such development and the lack of either regional governments with effective powers to regulate land use in most metropolitan areas or a strong state role in land use planning.
6. Changes in development patterns significant enough to substantially alter travel behavior and residential building efficiency entail other benefits and costs that have not been quantified in this study.
   
   

RECOMMENDATIONS

1. Policies that support more compact, mixed-use development and reinforce its ability to reduce VMT, energy use, and CO2 emissions should be encouraged.
2. More carefully designed studies of the effects of land use patterns and the form and location of more compact, mixed-use development on VMT, energy use, and CO2 emissions should be conducted so that compact development can be implemented more effectively.
1. Longitudinal studies
2. Studies of spatial trends within metropolitan areas
3. Before and after studies of policy interventions to promote more compact, mixed-use development
4. Studies of threshold population and employment densities to support alternatives to automobile travel
5. Studies of changing housing and travel preferences

The research council is rather reluctant to draw conclusions or advocate for significant adjustments to national cultural arrangements despite developing a correlation between residential density and VMT.  Many statements are made in defining Finding 2 that support additive layers of density enhancement that would push VMT reduction to the high end of the predictive range, but that also beg questions about the ways these elements are defined and the exclusion of certain others.

Increasing residential density alone will have little to no effect on VMT as long as large swaths of land are relegated to single-use zones as is acknowledged in Finding 5.  Questions arise from the report’s (and the general consensus) interpretation of mixed-use and the jobs-housing balance.  While I will admit that organic emergent urbanism created some untenable relationships between residents and heavy industrial sites from a health and safety standpoint, I would argue that this was still a more vibrant urbanism that allowed for a less energy intensive existence at the household level.  Now the pendulum has swung too far in the opposite direction.  Contemporary light industrial endeavors re-integrated into residential zones would augment one’s ability for transit or non-motorized commuting.  Mixed-use in today’s parlance seems to imply a rigid proportion of retail and residential, some office space often the only departure from the paradigm.  An eye to this type of potential utilization should become a bigger part of adaptive re-use efforts in order to diversify employment opportunities in reinvestment districts.  This will require a reversion of legislation that has made integrated communities, like the one seen at left, illegal.

The issue of adjusting for self-selection as it pertains to transportation preference and habit dominates the literature review somewhat unfairly.  It has been stated, most recently in George Washington University’s, ‘DC: The WalkUP Wake-Up Call (http://business.gwu.edu/Walkup.pdf),’ that demand for real estate in pedestrian-friendly urban neighborhoods significantly exceeds supply.  Shifting demographics and preference is one factor that the report acknowledges itself lacking as it pertains to the ability to interpret future trends.  Does the motivation of a resident of compact development devalue the neighborhood contribution toward reduced resource consumption?  Doesn’t policy play a major role in incentivizing behavior?  Would self-selection be so easily dismissed if it were a strategic decision rather than preference?

In closing, there must be a point at which the growing number of self-selecting individuals who prefer to avoid personal vehicular transportation becomes statistically significant enough that it cannot be dismissed as minority behavior.  Suburbanization was greatly aided by subsidizing the vast expansion of road capacity, mortgage availability and tax modification, zoning, and plentiful cheap energy.  One can envision a growing cohort of households which self-select due to economics rather than preference in a financial environment characterized by credit and capital scarcity.  These conditions undermine the ability to purchase, insure, maintain, and own personal vehicles.

The Future Isn't What It Used To Be

In order to properly plan for a sustainable future, we must resist the urge to rely on 100-year trends. It is the data collected in the last twenty or ten years that more accurately represents the shifting reality of housing preference, transportation efficiency, and energy cost/availability. These factors and more were analyzed last October by Todd Litman of the Victoria Transport Policy Institute (http://www.vtpi.org/future.pdf). Litman's overarching theme, that 20^th century transportation policy evolved due to a number of economic conditions that were favorable to automobile mobility, is inherently correct. Planning professionals need to recognize that these factors have either ceased to exist, or are highly unlikely to continue. They must understand why these things have occured or will occur in order to make the best recommendations for the deployment of future transportation resources. 

The United States was engaged in a national road-building fiesta from 1945 until sometime between 1980 and 1985. Relatively little additional roadway mileage has been added since, surprisingly. On the flipside, railroad mileage and transit service took a well known beating during this period, but the decline has indeed stopped and begun to reverse. Class I railroad mileage increased between 2000 and 2002, while rail transit track mileage increased a significant 40% from 1995-2002.

Perhaps more surprising, per-capita vehicle ownership reached its peak in 2000, long before the current protracted capital crisis, and declined slightly in the run-up to 2008. This is the first indicator of many that more than resource scarcity or economic contraction has begun to inform the habits of the average American in the 21^st century. Not only per-capita vehicular miles travelled (VMT) began to decline at the outset of the 2000's, but the total national VMT figure and total national fuel consumption both peaked approximately in 2006 and now annual VMT lags the obviously unsustainable long-term trend by approximately 10%. This phenomenon is not exclusive to the United States as most developed nations saw their per-capita VMT stabilize or decline since 2000, albeit at a much lower absolute figure than the U.S.

What is driving these shifts that are seemingly divorced from economic consideration? Real estate market research, such as that previously profiled by Christopher Leinberger in his excellent work, The Option of Urbanism (http://www.optionofurbanism.com/) is painting a picture of increasing sentiment toward a lifestyle less complicated by the onus of automobile ownership. According to Litman, twenty years ago, only a third of households stated a preference for what he calls 'smart growth' (smaller lot, better travel options, local services, and commute distances). His sources project a doubling of this opinion within two decades. In addition, a demographic wave of individuals who exhibit waning interest in cars are becoming actors in the land use demand marketplace. Theorists posit that this generation, which sees the automobile simply as an accessory of their sterile upbringing, finds more utility and enjoyment in increasingly social communications accessories than in a prosthetic conveyance. Regardless of the possible reason, statistics state clearly that the driver's license as American ritual is fading from the zeitgeist. Just 31% of 16 year olds had driver's licenses in 2008 compared with 42% in 1994. While there have never been more teenagers in the history of the country, less than 10 million of those are licensed to drive. The peak in this regard was reached back in 1978 when over 12 million youngsters plied the streets. One could reasonably estimate that simply using licensed individuals as a metric actually overstates the number of drivers as one never becomes unlicensed based on lack of usage. Such individuals are not retested, but are likely to retain the state driver's license as their primary form of photo identification.

Litman embarks on an examination of travel and freight transport trends in greater detail before arriving at a conclusion that weighs the balance of nine disparate impacts on vehicle travel demand (Table 4, Pg. 31). The realm of demographics falls squarely on the side of significant reductions as U.S. Residents born after 1978 drive significantly less (20%) than people of the same age did 10 years earlier. There is also a substantial decrease in per-capita VMT by people over 55. Operating costs of the current arrangement provide for moderate to large reductions over the long term due to rising fuel prices (increased demand/peak production) and the potential for toll increases. This signifies another reversal from the 50-year trend beginning in 1950 of reduced variable vehicle costs.

New technologies, primarily the increasing prevalence of work-from-home arrangements, but also including improved public transit user information and interface, encourage some likely declines in vehicular use. A note of caution is necessary on this topic to avoid the temptation to apply techno-grandiose solutions such as Magnetic Levitation trains. Quoting Litman, “...even if Maglev technology is perfected, it is only suitable for medium-distance trips on heavy traffic corridors. It may increase long-distance commuting in a few areas but have little effect on other travel.” What is important to understand about high-tech solutions versus low-tech solutions is that regardless of the mode, the mode must spur transit oriented development at its nodes in order to change travel patterns, and that these changes will be more a result of the land-use policy than the technology itself. A reliable lower-technology mode that still fosters these ideals is always preferable due to its design resiliency.

Consumer preferences and environmental concerns round out the list of key contributors to decline of vehicle travel demand. These two areas stem from household economic goals, health concerns, energy conservation, and emission reduction programs. The most immediate way to address both is to move from an auto-dependent suburb to a multimodal neighborhood where per-capita mileage reductions of 20-40% can be realized.

The implications to those would attempt to shape the built environment and transportation infrastructure are clear. Anticipation of future needs is critically important as we have seen in the past that public policy decisions are self-fulfilling. When planners at the height of the automobile age attempted to combat congestion with increased capacity, the result was additional induced traffic. We are in a new reality compared to the extrapolated results of 100-year trends. The continued allocation of the lion's share of resources to the dominant mode is an unsustainable proposition from a maintenance standpoint. The way to address this will be to strive for a more balanced transportation system that respects the mandates of reality and reason more than the desire to continue operating 'business as usual.'