Wednesday, February 3

From a mobility to an accessibility orientation

Over at the Planetizen Interchange blog, a fascinating debate has been brewing over the fundamental purpose of transportation. Todd Litman, Sam Staley, Michael Lewyn and a handful of commenters are involved. When debating transportation, we often jump right to the question of automobile vs. transit, but the more interesting dividing line lies beneath whatever technological tool we prefer. The tool of choice will arise inevitably out of what we intend to do with the system.

A mobility-oriented analysis, the conventional approach taken by transportation planners throughout the 20th century, is represented by Sam Staley. In his aptly titled book Mobility First, he defines this simply as:

"The ability to travel where you want when you want"
Working toward higher levels of mobility, for Staley, is a necessary condition for economic development and the maintenance of a high quality of life for Americans. This requires a combination of building sufficient capacity to meet travel demand and the efficient use of the capacity. For capacity, Staley calls for an aggressive government road-building regime, with thousands of miles of tunnels and multi-level expressways. For efficiency, he proposes a pricing system based on peak usage and levels of congestion.

In a mobility-oriented analysis, success is measured in terms of vehicle miles traveled - the more movement, the better. This position naturally leads Staley to hold the private automobile up as the ultimate mode of travel:
"Cars provide the automobility people want, fusing speed, flexibility, and adaptability into one travel technology. In a service-based economy faced with global competition, cars provide the most efficient, effective, and productive transportation alternative."
An accessibility-oriented analysis shifts the primary goal up one level. Instead of simply attempting to maximize the total amount of movement, this approach places primacy on the ability to reach a chosen destination. Todd Litman represented this side of the debate, and he has covered it more thoroughly here. His definition of accessibility:
"The ease of reaching goods, services, activities and destinations (together called opportunities). It can be defined as the potential for interaction and exchange."
It's a subtle difference with major implications. I've assembled a simplified flow chart to represent what I take to be the essential contours of an accessibility approach:
(In reality, there are overlaps and feedback loops between these categories. This just shows a hierarchy of goals.)

In this approach, mobility is not an end itself but a means to the end of improving access to destinations. Granted there are a few exceptions, such as joyriding, walking the dog around the block and other recreational activities, but, for the most part, users of the transportation system are concerned with reaching their destination. This interaction is also what truly drives economic and social health. Mobility no longer holds the trump card in an accessibility paradigm, but it must compete with land use arrangements and other alternatives to movement in a cost-benefit analysis. Litman again:
"Just as automobiles are machines that provide mobility, urban environments - villages, towns and cities - can be thought of as machines that provide accessibility by minimizing the distance among people and their desired goods, service and activities (shops, schools, jobs, neighbors, etc.)."
When mobility was considered the only game in town, the costs, however large, had to be shrugged off as a necessary evil. On top of all of the money poured into car-based infrastructure already, Staley claims "we probably need to spend at least a trillion dollars more on transportation over the next decade than we expect in revenues if we want to keep up with growth in travel and goods movement." (my italics). This is a significant chunk of the U.S. GDP, and it doesn't even count the costs of manufacturing and fueling the vehicles. He would like to slowly shift this immense burden from government to private citizens, which will surely add to the growing expense American households are already pouring into transportation.

Of course, there are the environmental costs, social equity costs and the costs in human lives. Roadway fatalities per capita have remained remarkably steady since 1960, even as medical care and general quality of life have improved significantly. Even in the most efficient system, there are the costs in the time it takes to move over longer distances. All of this needs to be figured into the equation.

There are immense benefits to mobility too, in all of its forms. None of this suggests that we can grind the world to a halt and still maintain the economic vitality we enjoy. It, however, does suggest a more holistic strategy - a full toolbox to respond to a broader challenge.

8 comments:

Eric Orozco said...

Thanks for distilling this and the handy chart...That's a great tool to think about interrelationships.

I always have to scratch my head at Libertarians. On the one hand there is this dogmatic insistence on personal choice. And yet they fixate on a "maximal" choices and denigrate other choices (however "cumbersome") as economically disadvantaged. Which actually betrays their limited understanding of the economic advantages of cities. "The community will suffer" ...Well, that one definitely cuts both ways. It is just befuddling to me how they are not looking out there at foreclosure boomburbia and missing a coherent reading of economic advantages.

Eric Orozco said...

Hey...Great comment on Staley's post. Exactly.

Cap'n Transit said...

Yes, thank you, and thank Litman! "The ability to travel where you want when you want"! So it's not just my right but a self-empowering act for me to buy a house with a big yard on Tristan da Cunha, and the government owes me a bridge to drive on?

Anonymous said...

The problem with talking about abstractions is often they tend to obfuscate as much as they illuminate.

Different employers in a city have different needs regarding mobility and access.

If we are talking about the profession of city planners, they probably can look for housing and shopping that is near their place of employment. There locus of employment is fairly fixed in a fairly confined area.

But in a lot of areas of the country, employment itself in the region is a direct consequence of high levels of mobility.

In Los Angeles one of the largest employers in the region are the Ports of Los Angeles and Long Beach. The freight and transportation industry in Southern California is one of the regions largest export industries. This is an industry that provides high wage employment to a lot of people with low levels of education/poor language skills. The fact that the combined Ports are the largest in the country results in all kinds of businesses deciding to co-locate in LA. So there are huge secondary employment consequences to LA losing mobility.

Part of the reason that the Port of Oakland lost share to the Ports of LA and Long Beach is that freeway congestion in the Bay Area was so bad.

For the shipping industry, access means access to sites in the rest of the country. If it takes too long to ship a good from LA to Denver, Salt Lake City or Phoenix, the goods will go through Oakland or Seattle. If that happens to often, the business that co-locate with the ports will also move. The Nestle US headquarters in Glendale, the Bugle Boy Jeans company probably wouldn't be in LA if the Ports in LA weren't so huge.

Cities that aren't port cities are still often transportation hubs. During the railroad era, Chicago grew because all railroads in the country converged on Chicago. But during the Just in Time era of manufacturing, Trucks were favored over trains, Atlanta has grown because it has such great freeway connections to the rest of the country.

There also industries that agglomerate along freeway corridors. 58% of the auto plants and suppliers in this country are in just 5 states, along I-65 and I-75 in Michigan, Ohio, Indiana, Kentucky and Tennessee.

http://www.uwlax.edu/faculty/knowles/eco303/ecogeo2.pdf

Making sure that trucks can get in and out in a timely fashion is what allows these just in time factory systems to work. If city planners in these cities screw up mobilty to shift people out of cars and into transit, they can also kill off the primary employer in these communities.

One of the big reasons the border cities of Northern Mexico are wealthier (like Tijuana, Juarez and Monterrey) than the border cities of Southern Mexico is that these cities benefit from the really good transportation networks in the US that allow them to function as part of nationwide US economy. In Southern Mexico the lack of transportation between cities makes these cities function as there own smaller poorer economic units. This is why most US immigration from Mexico is from the southern poorer part of Mexico.

Lack of mobility will push out and destroy a lot of industries in a community and make the region itself poorer.

Daniel said...

First of all, I'm not sure if the job of a planner is less mobile than any other. Many have to make frequent trips around a jurisdiction for public meetings and other events. Private consultants travel all over for clients. The job structure itself seems hardly grounds for an institutional bias against mobility, in my opinion.

But more to the point. I see two main arguments you're making. You say that there are direct employment benefits from the transportation industry. This is true, and maybe a recession is not the time for major economic restructuring, but isn't this argument just old-fashioned protectionism? Economies evolve and new technologies replace old. I know that Detroit can use jobs, but ultimately we would like to see production shift into its most efficient form, and this requires letting go of any inherent privileges we choose to give to specific favorable industries. (This isn't to say there may be a government role for helping workers make the transition). Mobility-providers will always be important, but I don't see why these jobs are more valuable than others.

Secondly, you point to the macro-economic benefits of high mobility, specifically shipping. All I can say is that I agree, but I don't understand how this is negates anything from this post. There are tremendous economic benefits to proximity as well, which is really what agglomeration is all about. Atlanta is benefited by its freeways and airport, but it's also benefited by its location on the eastern seaboard with a large population within regional reach. Move Atlanta, freeways and all, to northern Canada and much of the competitive advantage vanishes. I'm using "access" to mean the combination of mobility and proximity, and other factors. Atlanta has fared well because of its access.

CarFree Stupidity said...

So... commuting 90 miles to work = increased VMT = more mobility = good for everyone. I think that line of thinking = BS

Seems to me this equation is leaving out opportunity costs. The 1 1/2 hours spent commuting could be used more productively (spending time with family, working, buying shit, etc.) than by transporting my 170 Ibs body in a 2 ton vehicle.

For the most part, today's transportation infrastructure forces a choice on people, they have no option other than to drive. So yes you can get very far on America's freeways in a relatively short amount of time but that doesn't necessarily mean this arrangement is the most efficient... especially once opportunity costs, social costs, and environmental costs are factored in.

Richard Layman said...

awesome diagram

Daniel said...

Thanks Richard. I'm hope anyone feels free to use it.