Traffic

by Tom Vanderbilt

  car was given ACC: The ACC study results are described in L. C. Davis, “Effect of Adaptive Cruise Control Systems on Traffic Flow,” Physical Review E, vol. 69 (2004).

  Chapter Five: Why Women Cause More Congestion Than Men

  1.1 hours: Andreas Schafer and David Victor, “The Past and Future of Global Mobility,” Scientific American, October 1997, pp. 58–63.

  made more frequent, shorter trips: Vacov Zahavi, “The ‘UMOT’ Project,” August 1979, prepared for the U.S. Department of Transportation and the Ministry of Transport, Federal Republic of Germany, Bonn.

  in one hour: Cesare Marchetti, “Anthropological Invariants in Travel Behavior,” Technological Forecasting and Social Change, vol. 47 (1994), pp. 75–88.

  thirty minutes each way: M. Wachs, B. D. Taylor, N. Levine, and P. Ong, “The Changing Commute: A Case-study of the Jobs-Housing Relationship over Time,” Urban Studies, vol. 30, no. 10 (1993), pp. 1711–29.

  jobs were located: See David Levinson and Ajay Kumar, “The Rational Locator,” Journal of the American Planning Association, vol. 60, no. 3 (1994), pp. 319–43. Similar trends have been observed in the Portland area, as described in Robert L. Bertini, “You Are the Traffic Jam: An Examination of Congestion Measures,” paper submitted to Eighty-fifth Annual Meeting of the Transportation Research Board, January 2006, Washington, D.C.

  jacking up the numbers: D. Levinson and Y. Wu, “The Rational Locator Reexamined,” Transportation, vol. 32 (2005), pp. 187–202.

  prompts more driving: See Nancy McGuckin, Susan Liss, and Bryant Gross, “Do More Vehicles Make More Miles?” National Household Travel Survey (Washington, D.C.: Federal Highway Administration, 2001).

  the worse the traffic congestion: Anthony Downs, “Why Traffic Congestion Is Here to Stay…and Will Get Worse,” Access Magazine, no. 25 (Fall 2004). See also Scott F. Festin, Summary of National and Regional Travel Trends: 1970–1995 (Washington, D.C.: U.S. Department of Transportation, Federal Highway Administration, 1996).

  figure is 48 percent: Figures supplied by Alan Pisarski.

  roughly 16 percent: Alan Pisarski, Commuting in America III (Washington, D.C.: Transportation Research Board, 2006), p. 2.

  over 32 miles: Susan Handy, Andrew DeGarmo, and Kelly Clifton, Understanding the Growth in Non-Work VMT, Research Report SWUTC/02/167222 (Austin, Texas: Southwest Region University Transportation Center, University of Texas, February 2002), p. 6.

  whole day to complete: For a good discussion of recent changes in women’s travel behavior, see Rachel Gossen and Charles Purvis, “Activities, Time, and Travel: Changes in Women’s Travel Time Expenditures, 1990–2000,” Research on Women’s Issues in Transportation, Report of a Conference, Vol. 2 (Washington, D.C.: Transportation Research Board, 2004).

  are now fam-pools: Nancy McGuckin and Nandu Srinivasan, “The Journey-to-Work in the Context of Daily Travel,” paper presented at the Transportation Research Board meeting, Washington, D.C., 2005.

  statistically driving more miles: Survey data in the United States indicates what seems like an intuitive fact: The more members in a household, the more miles it drives. “Travel within households increases by household size and income,” as Nancy McGuckin put it to me in an e-mail correspondence.

  precocious car poolers: See, for example, Christina Sidecius, “Car Pool Lane Not for Dummies,” Seattle Times, August 2, 2007.

  more often than men do: See Research on Women’s Issues in Transportation: Report of a Conference (Washington, D.C.: Transportation Research Board, National Research Council, 2005), p. 30.

  about 15 percent do: Jane Brody, “Turning the Ride to School into a Walk,” New York Times, September 11, 2007.

  by some 30 percent: See U.S. Environmental Protection Agency, Travel and Environmental Implications of School Siting, EPA 231-R-03-004, October 2003, and Department of Environment, Transport and the Regions, London, Greater Vancouver Regional District, Morning Peak Trip by Purpose, 1999.

  sports in America doubled: Charles Fishman, “The Smorgasbord Generation,” American Demographics, May 1999.

  trips are getting longer: Handy, DeGarmo, and Clifton, Understanding the Growth in Non-Work VMT.

  typical rush hours: See Highway Statistics 2005 (Washington, D.C.: Office of Highway Policy Information, Federal Highway Administration).

  closest to their home: Susan L. Handy and Kelly J. Clifton, “Local Shopping as a Strategy for Reducing Automobile Dependence,” Transportation, vol. 28, no. 4 (2001), pp. 317–46.

  did a few decades ago: Handy, DeGarmo, and Clifton, p. 31.

  it was .79 miles: Handy, DeGarmo, and Clifton, p. 29.

  was completely alien: See the report by the Technical Committee of the Colorado-Wyoming Section of the Institute for Transportation Engineers, “Trip Generation of Coffee Shops with Combination Drive-Through and Sit-Down Facilities” retrieved from http://www.cowyite.org/technical/.

  left turn during rush hour: Starbucks also anticipates traffic flow in another way: It likes to locate stores near dry cleaners and video rental shops in order to capture the “dropping off” and “picking up” traffic flows (two chances to sell that double latte). See Taylor Clark, Starbucked (New York: Little, Brown, 2007).

  stalled queues of cars: Andrew Downie, “Postcard: Brazil,” Time, September 27, 2007. The author drily notes: “Motorbikes account for 9% of the city’s vehicles but they cause more accidents than all the rest combined, according to city traffic officials. That means moto-medics also come with a dose of irony.”

  all other travel methods: Pisarski, Commuting in America III, p. 109.

  those without one: “Poverty and Mobility in America,” NPTS Brief (Washington, D.C.: U.S. Department of Transportation, Federal Highway Administration, December 2005).

  than public transit: See Brian D. Taylor, “Putting a Price on Mobility: Cars and Contradictions in Planning,” Journal of the American Planning Association, vol. 72, no. 3 (Summer 2006), pp. 279–84.

  near the top: Daniel Kahneman, Alan Krueger, Norbert Schwarz, and Arthur Stone, “A Survey Method for Characterizing Daily Life Experience: The Day Reconstruction Method,” Science, vol. 306, no. 5702 (December 2004), pp. 1776–78.

  but sixteen minutes: Mokhtarian raises the point that people in such surveys may be confusing the idea of “ideal commute” with what commute they would be willing to make; she also notes that they might be giving what they consider to be a “realistic” ideal and not, say zero minutes. See Patricia L. Mokhtariand and Lothlorien S. Redmond, “The Positive Utility of the Commute: Modeling Ideal Commute Time and Relative Desired Commute Amount,” Berkeley: University of California Transportation Center, Reprint UCTC No. 526.

  figuring out alternatives: S. Handy, L. Weston, and Patricia L. Mokhtarian, “Driving by Choice or Necessity?” Transportation Research Part A: Policy and Practice, vol. 39, nos. 2–3 (2005), pp. 183–203.

  rational perspective: Alois Stutzer and Bruno S. Frey, “Stress That Doesn’t Pay Off: The Commuting Paradox” (September 2004), IZA Discussion Paper No. 1278, Zurich IEER Working Paper No. 151. Available at SSRN: http://ssrn.com/abstract=408220.

  grown the most: Robert H. Frank, Falling Behind (Berkeley: Univ. of California Press, 2007), p. 82.

  “hedonic adaptation”: See S. Frederick and G. Loewenstein, “Hedonic Adaptation,” in Scientific Perspectives on Enjoyment, Suffering, and Well-Being, ed. D. Kahneman, E. Diener, and N. Schwartz (New York: Russell Sage Foundation, 1999), pp. 303–29.

  more prone it is to variability: Nancy McGuckin and Nandu Srinivasan, “The Journey-to-Work in the Context of Daily Travel,” paper presented at the Transportation Research Board meeting, 2005. Washington, D.C.

  actual time itself: See, for example, Harry Cohen and Frank Southworth, “On the Measurement and Valulation of Travel Time Variability Due to Incidents on Freeways,” Journal of Transportation and Statistics, vol. 2, no. 2 (Dec. 1999), as well as David Brownstone and Kenneth A. Small, “Valuing Time and Reliability: Assessing the Evidence
from Road Pricing Demonstrations,” Transportation Research Part A: Policy and Practice, vol. 39, no. 4 (2005), pp. 279–93.

  “hell every day”: Jonathan Clements, “Money and Happiness? Here’s Why You Won’t Laugh,” Wall Street Journal, August 16, 2006.

  higher rate than are passenger cars: T. Cohn, “On the Back of the Bus,” Access, vol. 21 (1999), pp. 17–21.

  into early retirement: The information on urban bus drivers comes primarily from the work of Gary Evans, a professor of human ecology at Cornell University. See, for example, Gary Evans, “Working on the Hot Seat: Urban Bus Drivers,” Accident Analysis & Prevention, vol. 26 (1994), pp. 181–93; G. Evans, M. Palsane, and S. Carrere, “Type A Behavior and Occupational Stress: A Cross-cultural Study of Blue-Collar Workers,” Journal of Personality and Social Psychology, vol. 52 (1987), pp. 1002–07; and Gary W. Evans and S. Carrere, “Traffic Congestion, Perceived Control, and Psychophysiological Stress Among Urban Bus Drivers,” Journal of Applied Psychology, vol. 76 (1991), pp. 658–63.

  how much they’re dating: F. Strack, L. L. Martin, and N. Schwarz, “Priming and Communication: The Social Determinants of Information Use in Judgments of Life-Satisfaction,” European Journal of Social Psychology, vol. 18, 1988, pp. 429–42.

  “focusing illusion”: Daniel Kahneman, Alan B. Krueger, David Schkade, Norbert Schwarz, and Arthur A. Stone, “Would You Be Happier If You Were Richer? A Focusing Illusion,” Science, vol. 312, no. 5782 (June 30, 2006), pp. 1908–10.

  makes them think it is: We are also quite capable of changing the way we feel about something—or the way we think we feel about something—simply by subtly changing our definitions of what is important. A fascinating example of this was seen when a group of psychologists from various countries decided to interview solo drivers before and after a car-pool lane was built on a highway in the Netherlands. They conducted similar interviews on a “control” highway that was not getting a new car-pool lane. When the car-pool lane was added, saving about twenty minutes for those in it, solo drivers’ attitudes seemed to change. It was not as if they suddenly had a more positive opinion of driving alone and a more negative opinion of carpooling, per se. What did change was how important they felt certain aspects of their commute were. Suddenly, “flexibility” ranked as more important, and saving money or travel time less so. On the highway without a car-pool lane, drivers’ attitudes remained the same. But on the highway where the new car-pool lane appeared, teasing solo drivers with its uncongested pleasures, they suddenly had less of a preference for carpooling than when it had not been there. Rather than change their behavior or be haunted every day by not “doing the right thing,” they were suddenly telling themselves new stories about what was important to them. (Interestingly, they did not change their attitudes toward what was best for the environment, even if their own behavior did not follow suit.) They were justifying their actions to themselves—that is, making themselves feel better. It could be that rounding up the car pool would take longer than the lane would save (even if a car pool would still be better for the environment and traffic congestion). It could also be that many people, as mentioned above, simply cannot carpool. But it also seems that people, when actually shown an alternative that would be better for society at large, are good at finding ways to explain why it would not be good for them. A driver stuck in traffic watching a commuter train speed by does not necessarily think, “I wish I were on that train,” but instead tries to console himself with the reasons he cannot be on that train. And so the roads are filled with people wondering why there are so many other people on the roads, all of them convinced of the reasons they need to be there. See Mark Van Vugt, Paul A. M. Van Lange, Ree Meertens, and Jeffrey Joireman, “How a Structural Solution to a Real-World Social Dilemma Failed: A Field Experiment on the First Carpool Lane in Europe,” Social Psychology Quarterly, vol. 59 (1996), pp. 364–74.

  less than 15 percent: Brian Taylor, “Rethinking Traffic Congestion,” Access, Fall 2002, pp. 8-16.

  like a bell: There are interesting regional variations on this. In Arizona, for example, it has been observed that parking spaces closest to the store are often empty, as cars gravitate first toward the perimeter of the lot, where trees might provide some shade. As one article put it, “A long walk to the store is far better than driving home in a car that has baked for hours in the desert heat.” From Diane Boudreau, “Urban Ecology: A Shady Situation,” Chain Reaction, vol. 4 (2003), pp. 18–19. For more on the microclimate differences between tree-shaded parking lots and those without, see Klaus I. Scott, James R. Simpson, and E. Gregory McPherson, “Effects of Tree Cover on Parking Lot Microclimate and Vehicle Emissions,” Journal of Arboriculture, vol. 25, no. 3 (May 1999), pp. 129–41.

  bell-curve arrangement: This idea was first suggested, as far as I can discern, at the following Web site: http://vandersluys.ca/?p=7914.

  not necessarily being chosen: Velkey’s findings matched those predicated by two engineering professors in a “probabilistic model.” See C. Richard Cassady and John E. Kobza, “A Probabilistic Approach to Evaluate Strategies for Selecting a Parking Space,” Transportation Science, vol. 32, no. 1 (January 1998), pp. 30–42.

  to walk somewhere: Travel Behaviour Research Baseline Survey 2004: Sustainable Travel Demonstration Towns (SUSTRANS and Socialdata, 2004). Retrieved from http://www.sustrans.org.uk/webfiles/travelsmart/STDT%20Research%20FINAL.pdf.

  was at work: The “availability heuristic” is credited to Daniel Kahneman and Amos Tversky. (Heuristic is a sophisticated-sounding word that really just means “mental shortcut.”) When people are asked to imagine how often something happens, they tend to overestimate the probability of things that can be more easily recalled from memory—that is, that are “available”—or that loom more vividly in the imagination.

  mixed conclusions on this: See, for example, R. G. Golledge, K. L. Lovelace, D. R. Montello, and C. M. Self, “Sex-Related Differences and Similarities in Geographic and Environmental Spatial Abilities,” Annals of the Association of American Geographers, vol. 89 (1999), pp. 515–34.

  as the distance did: A. J. Velkey, C. Laboda, S. Parada, M. L. McNeil, and R. Otts, “Sex Differences in the Estimation of Foot Travel Time,” paper presented at the annual meeting of the Eastern Psychological Association, Boston, March 2002. One factor that might lead women to overestimate distances is that, as previous studies have shown, distance estimations tend to be skewed in unpleasant or stressful surroundings. Women may not feel safe in large parking lots, which may help distort the sensation of how close or far a potential parking space is. See Sigrid Schmitz, “Gender Differences in Acquisition of Environmental Knowledge Related to Wayfinding Behavior, Spatial Anxiety and Self-Estimated Environmental Competencies,” Sex Roles: A Journal of Research, July 1999.

  “optimal foraging”: For a good introduction to optimal foraging, see T. Schoener, “A Brief History of Optimal Foraging Ecology,” in Foraging Behavior, ed. A. C. Kamil, J. R. Krebs, and H. R. Pulliam (New York: Plenum Press, 1987), pp. 5–67. See also Jeffrey A. Kurland and Stephen J. Beckerman, “Optimal Foraging and Hominid Evolution: Labor and Reciprocity,” American Anthropologist, vol. 87, no. 1 (March 1985), pp. 73–93.

  the effort of looking: This example is given in an interesting paper by Elizabeth Newell, a biologist at Hobart and William Smith Colleges, titled “The Energetics of Bee Foraging.” Retrieved from http://www.life.umd.edu/Faculty/inouye/Pollination%20Exercises/Beth’s.htm.

  is the better option: Esa Ranta, Hannu Rita, and Kai Lindstrom, “Competition Versus Cooperation: Success of Individuals Foraging Alone and in Groups,” American Naturalist, vol. 142, no. 1 (July 1993), pp. 42–58.

  spot to a destination: Mark Schlueb, “To Get to Game or Show, Parking May Be Tricky,” Orlando Sentinel, December 1, 2006.

  destination is in sight: See Daniel R. Montello, “The Perception and Cognition of Environmental Distance: Direct Sources of Information,” in Spatial Information Theory: A Theoretical Basis for GIS (Be
rlin: Springer, 1997), pp. 297–311, and Lorin J. Staplin and Edward K. Sadalla, “Distance Cognition in Urban Environments,” Professional Geographer, vol. 33 (1981), pp. 302–10.

  is “good enough”: See Herbert Simon, Administrative Behavior, 4th ed. (New York: Free Press, 1997).

  of their time parked: Donald Shoup, The High Cost of Free Parking (Chicago: American Planning Association, 2005), p. 6.

  subsidized parking spots: Bruce Schaller, “Free Parking, Congested Streets,” March 1, 2007; available at http://www.schallerconsult.com/pub/index.htm.

  “as has cycle parking space”: City of Copenhagen, Traffic and Environmental Plan 2004, p. 16.

  “that will avoid shortages”: Shoup, The High Cost of Free Parking, p. 303.

  metered street spots: Donald C. Shoup, “Cruising for Parking,” Transport Policy, vol. 13 (2006), pp. 479–86.

  to thirteen minutes: Shoup, The High Cost of Free Parking, p. 279.

  “vehicle per block was enough”: William Whyte, City (New York: Doubleday, 1988), p. 72.

  all urban traffic collisions: See Paul C. Box, “Curb Parking Findings Revisited,” Transportation Research Circular 501 (Washington, D.C.: Transportation Research Board, 2000).

  8 miles per hour: This estimate, for streets with both parking and trees, comes from Dan Burden, “22 Benefits of Street Trees,” Glatting Jackson/Walkable Communities, Summer 2006.

  shiny black sealcoat: See Peter C. Van Metre, Barbara J. Mahler, Mateo Scoggins, and Pixie A. Hamilton, “Parking Lot Sealcoat: A Major Source of Polycyclic Aromatic Hydrocarbons (PAHs) in Urban and Suburban Environments,” Fact Sheet 2005–3147 (Austin: U.S. Geological Survey, January 2006). Not surprisingly, the authors report that PAHs seem to be on the rise: “USGS findings show that concentrations of total PAHs in the majority of lakes and reservoirs in urban and suburban areas across the nation increased significantly from 1970 to 2001. The increases were greatest in lakes with rapidly urbanizing watersheds (urban sprawl); for example, over the last 10 years, the concentrations of PAHs in Lake in the Hills (suburban Chicago, Illinois) increased tenfold as the watershed was rapidly developed.”