Measuring the Broader Impacts of Transportation

CEOs for Cities recently published a blistering criticism of The Texas Transportation Institute's "Urban Mobility Report", saying that the way they measure mobility helps justify sprawl. Norman W. Garrick says CEOs for Cities doesn't go far enough.

A recent study from the CEOs for Cities criticizing the Texas Transportation Institute's Urban Mobility Report has rightly garnered a lot of interest. Their case against the TTI main index is correct, but does not go far enough.

The debate between CEOs for Cities and TTI is really about methodology. The distinction being discussed is important – but ultimately the focus of both groups is still somewhat missing the point. They are both still centered on measuring just one facet of how well transportation is serving us. Thus it is a limited debate about how to measure mobility of people in cars - as if that is all that matters when it comes to assessing how well the transportation system is serving society.

Image courtesy of Flickr user sparktography.

Over 50 years ago, Lewis Mumford posed the question "What is transportation for?" Mumford felt that if we had asked this simple question at the start of the interstate era we might not have committed billions of dollars to the creation of what he called a monochromatic transportation system. In his view, we supported highways to the detriment of transit and cities, mainly because transportation began to be seen as end in itself - rather than a means to an end. We lost sight of the fact that a transportation system affects almost all aspects of daily life and that its value should not be judged purely on the basis of how well it affords the easy movement of vehicles.

Recently, there have been signs that after fifty years under this regime - where mobility considerations ruled all our decisions about transportation - the tide is beginning to turn. The new emphasis of the US DOT, HUD and EPA on the issues of transportation and livability is one sign of the first tentative steps being taken to place transportation in a broader context. Some have pointed out that the concept of livability as it is current posed is still somewhat nebulous. This is true, but the fact remains that the discussion of livability signals an important change in focus at the federal level. What is needed now are ways of measuring these broader impacts that are implied by the term livability. This will allow us to effectively assess the extent to which transportation is serving our real interests, over and above considerations relating to vehicle mobility.

By focusing on transportation in a broader context we will be able to start to address questions such as the true cost of focusing so much attention to vehicle mobility. To answer questions like these and others about the broader impacts of transportation, our team at UCONN is working to develop the Transportation Index for Sustainable Places. One component of this TISP considers the cost of transportation from the perspective of both the individual and the society as a whole.

This assessment is based on the following four points:

  • Transportation is Affordable for Individuals
  • Transportation System Provides Efficient Movement of People & Goods for Economic Activity
  • Transportation Finance is Locally Self-Sufficient
  • Transportation System Does Not Contribute to Economic Vulnerability of Society

Each state was graded on these four points and then a composite score was determined for rating the states. The results of these ratings showing how well the states stack-up in terms of the economic impact of their transportation system is given in the map below.

On this map the best performing state is New York, and the worst is Mississippi. The differences between the states are stark – for example, in New York only 21% of the average household income is spent on transportation, while in Mississippi transportation eats up a crushing 41% of the average household income. In New York only 1% of the state's GDP is spent on transportation fuel, while Mississippi devotes almost 5% of its state GDP to the purchasing of transportation fuel.

In addition, New York State is much less dependent on the federal government to support its total transportation budget – only 15% of its budget comes from the federal purse while Mississippi depends on the federal government to provide a whopping 41% of total transportation budget. But perhaps more telling is the fact that in New York State, over a 10-year period, the GDP grew at a rate 3 times faster than the growth in vehicle miles travelled. In Mississippi we actually had the perverse situation in which vehicle miles grew at a rate three times faster than the rate of growth in GDP.

One obvious factor that account for the difference between New York State and Mississippi is their disparate level of urbanism. To account for this important factor we used census data to divide the states into four categories ranging from the most rural to the most urban. Perhaps not surprisingly, the most urban states generally performed better on our index of the economic impact of transportation. However, there was still a large variation between the states in each category. For example, amongst the most rural states the percentage of household income spent on transportation ranged from 21% to 41%. This suggests that differences in state policies might be playing a significant role in the observed outcomes.

Index of Economic Impact of Transportation (red = worst, green = best)

Most significantly we found that those states that had the most 'monochromatic' transportation systems (that is the ones with the highest amount of car use) scored the worst on our index. Those of you that are familiar with the map of obesity rate by states might notice some similarity between that map and our mapping of the economic impact of transportation. It is important to remember that the data we have mapped to date only includes the economic outcomes, which is only one of the three components of our Transportation Index for Sustainable Places. The other two components – the environmental and social (which includes health and safety impacts)– are not reflected in the results presented here. Our preliminary work in these areas suggests that the effects of transportation in all three areas are interrelated. Therefore, the similarities noted between our economic results and the obesity results is another reminder that we urgently need a broader framework for assessing the impact of transportation.

The CEOs for Cities research makes an important point about the fact that we need accurate measures of vehicle mobility if we are to develop better public policy. But the larger point is that we also need to understand that transportation is about much more than vehicle mobility. We need to have effective measures for assessing these broader impacts of transportation. Otherwise, our fixation on the mobility aspect of transportation will mean a continuation of local, state and federal policies that cost too much over the long run, wreck the character of our cities and damage the environment.

Norman Garrick, PhD is an associate professor of civil and environmental engineering at the University of Connecticut. He is also a board member of the Congress for the New Urbanism.



Purpose of Transportation

As David Owen (Green Metropolis, 2009) shows, dense, mixed-use urban development represents the best 'imbedded efficiency" in both housing and transportation.

To me the function of a city is to maximize commerce while minimizing commotion (and note that "motion" is part of "commotion").

There is a scalar hierarchy of space and time, such that the things we access most frequently should be closest to us (look how we organize kitchens and offices). By that metric, commutes are too long in 'developed' countries, and retailing is getting more spread out than is necessary.

Not only are cars means to ends, but the movement of a driver is also often the same, since what is really being moved is a thing or person who can't drive, often much smaller in weight and size.

Distance induces speed and, together, impose formality of movement. Formality imposes wider spaces and separation, rules, and higher expenses (private and public). Driving is the most regulated and watched of all human activities. Walking is the opposite, appropriately.

The study shows transportation costs to vary greatly, but doesn't examine housing costs, "the other shoe." CNT (Center for Neighborhood Technology) shows that as one goes down, the other goes up (but the low-density combo usually costs more). We need for people to prefer investing in housing (which usually appreciates and is not dangerous or unhealthy to use), and disinvesting in automobiles, which is worse on all counts.

Enough damage already, please.

I am reading more and more from analysts like Peter Gordon, William Wheaton, and Randall Crane, that support my current concerns.

That is, that monocentrically biased planning and urban growth boundaries have "land value" effects that actually reduce the option of "location efficient" decisions by households, especially the lowest income earners. It also leads to concentration of wealth in the hands of the owners of efficiently located properties via capital gains, especially the most expensive CBD properties. And it also reduces naturally occurring economic efficiencies from efficient location decisions that households COULD make BEFORE land prices were inflated. The economic growth, wealth creation effect of demand-enabling mobility, that is also reduced.

NOW we have THIS paper:

http://www.dukakisc storage/TRNEquit yFull.pdf

The escalation of land values around Transit stops is captured by better-off property owners, and lower income earners are priced out of the market en mass. Well, spare me days. I couldn't agree more with the findings, or disagree more with the recommended "solutions".

Correct URL


Another important correlation to look for. How flexible or inflexible is zoning and land use?

Alain Bertaud's studies "Cities Without Land Markets", and "The Costs of Utopia", show how the cities of the former USSR were based on high density living and passenger rail transport, and yet were possibly the least efficient users of resources in the world. The deciding factor there, was the efficiency of LOCATION decisions.

Being within 5 minutes by auto, of work, schools, retail, and sports and cultural amenities; is obviously more efficient than being 1 hour from each by train.

I am continually concerned by planners obsession with modes of travel, and relative ignorance about the perverse consequences of zoning and land use planning - not the least of which involves the "land price" consequences of planning.

New Metrics

Spot on Norman, we do need new metrics and they should be action oriented and easily monitored. I recently blogged about these new metrics at In short the blog posts describes how Copenhagen, now a model of success for transportation choice shifted away from metrics generated by complex (and often inaccurate) computer forecast models to real-life measures of urban quality. The number of new street cafes, miles of bike lanes, number of street chairs and seating areas and store fronts enlivened are tracked annually to provide Copenhagen with a gauge of progress. Another simple measure they take of the urban condition is done at the block level sample size, where they measure how many people (in cars, bikes, transit vehicles, walking and sitting) are using the street or public space. How long people sit and stay is of great concern to the Danish. They know the longer people stay in a place indicates urban quality and the economic potential of an area. If they aren’t staying long, than that area needs a more inviting public space. Thanks again Norman for highlighting the importance of this report and need for the planning world to embrace new standards for mobility that go beyond technocratic data.

Andrew Howard, AICP, CNU

Prepare for the AICP* Exam

Join the thousands of students who have utilized the Planetizen AICP* Exam Preparation Class to prepare for the American Planning Association's AICP* exam.
Starting at $245

Essential Readings in Urban Planning

Planning on taking the AICP* Exam? Register for Planetizen's AICP * Exam Preparation Course to save $25.
 Blockitecture Building Block Set - Garden City Series

Just In! Get the Garden City Expansion

New from Blockitecture! Create towers, cities, and dwellings with this set of architectural building blocks.
Book cover of Insider's Guide to Careers in Urban Planning

So you want to be a planner...

Check out our behind the scenes look at 25 careers in the Urban Planning field
Starting at $14.95