Part of a series of “reading memos” that offer a brief summary of interesting academic content along with my personal reflections. This one covers Chapters 1 and 3 of Giuliano & Hanson’s The Geography of Urban Transportation.
Introducing Urban Transportation
The author begins by distinguishing between accessibility (the ease of reaching activities/opportunities) and mobility (the physical ability to move between locations). Better accessibility can be achieved by increasing mobility (faster cars/trains/etc.) but it’s now recognized that a more sustainable approach involves better land use (i.e., creating high-density and mixed-use neighborhoods). Other factors to be considered when designing transportation options include equity (who wins / who loses) and externalities (unpriced side-effects of the use of certain modes).
A few national trends are discussed, including the increase of single-person households (which typically take more trips than larger households), the decrease in population in central cities (versus suburbs), the growth in households with more than one car, the decentralizing of employment into suburbs, the spatial correlation of poor / carless / female-headed households (populations with special transportation needs) in central cities, the steady rise in vehicle miles traveled (VMT) per person in the United States, the increase in distances (but not time) for work trips, and nonwork travel growing at a faster rate than work travel.
I really valued the coverage of demographic, employment, and travel patterns in the United States as it sets the context necessary for transportation planners to make well-informed decisions for the long-term. I was also disappointed to see that these trends were similar in Europe but was impressed that they didn’t result in the extreme levels of automobile dependency we see in the United States due to differences in public policy. This shows that there is a path for the United States to encourage more walking/biking/transit usage, should we decide to shift our transportation policies accordingly.
The introduction to technical concepts that planners can use to study movement patterns such as the space-time prism (a representation of an individual’s space-time autonomy given capability / coupling / authority constraints) and aggregate (area-level focus on trips between zones) / disaggregate (individual-level daily travel activity patterns) data was also helpful. This terminology will certainly be helpful to understand travel pattern studies and justifications for major transportation infrastructure decisions in the future.
Transportation and Urban Form
In this chapter, Muller identifies four distinct eras of transportation development that each shaped the form of American cities in unique ways. Since people are generally only willing to travel about 30-45 minutes for their daily activities, each innovation in transport enabled progressively more distributed development.
- The Walking-Horsecar Era (1800-1890) initially forced people and industry to concentrate very closely near city centers, resulting in unpleasant conditions (noise, epidemics, etc.). The introduction of the horse-drawn streetcar enabled wealthy and eventually middle-income urbanites to begin commuting from “horsecar suburbs” while nonaffluent and immigrant populations remained in the crowded pedestrian centers.
- The Electric Streetcar Era (1890-1920) enabled prolific development along trolley corridors, resulting in star-shaped cities with little in the interstices. It also facilitated the creation of ethnic neighborhoods as people dispersed from the mixed inner-city tenements into separate enclaves.
- The Recreational Automobile Era (1920-1945) initiated a drastic shift in the urban form as personal car ownership enabled people to live far from established traction-line corridors. This is when suburbs began growing faster than central cities and mass transit ridership began its decline, trends that continue into the modern era.
- The Freeway Era (1945-present) is when cars became a necessity rather than a luxury. The 1956 Interstate Highway Act flipped the power dynamic between the inner city and the suburbs, enabling new job and activity centers in suburban downtowns (“edge cities”).
Muller argues that this pattern of development will persist into the foreseeable future (despite claims of an “urban renaissance”) and that planners must learn to work with this reality. This is somewhat disappointing given the known downsides (balkanization of society, health risks of automobile dependency, etc.), but there was a glimmer of hope given in the example of Tyson’s Corner in Virginia where a new metro line has spurred the transformation of a suburban downtown into a dense, walkable, transit-oriented corridor.