No Light Rail in Vancouver!

The Prediction Problem: Planners Aren’t Prophets

Jan 12

2007

During World War II, Kenneth Arrow–who would receive the Nobel Prize in economics in 1972–served as a part of the weather forecasting service for the Army Air Corps. As Peter Bernstein recounts in his 1998 book, Against the Gods, Arrow and his colleagues soon realized that their long-range forecasts were no better than numbers pulled out of a hat, and they asked to be assigned to more useful work.

“The Commanding General is well aware that the forecasts are no good,” they were told in reply. “However, he needs them for planning purposes.”

Forecasting the future is no more accurate today than it was sixty-five years ago. Yet planners continue to write “long-range plans” that purport to look ahead ten, twenty, even fifty or a hundred years. For such plans to be worthwhile, planners must be able to answer questions such as:

• What technologies will be available in the future?
• How much will land, energy, and other resources cost?
• How will individual tastes and preferences change?
• How will people earn their incomes?

None of these plans can be answered with any degree of confidence. Yet any long-range plan that is based on the wrong answers is likely to create far more problems than it solves.

Imagine writing a plan for your city back in 1950:

• Few people had ever flown, and no one had ever flown in a commercial jet airliner.
• Few people had ever worked with computers, and not even the most far-seeing science-fiction writers had predicted microcomputers or the Internet.
• Long-distance phone calls were expensive, and no one had ever made a direct-dial long-distance call.
• Few married women worked, and the highest-paid jobs were all held by men.
• Few other countries could match the United States as a manufacturing powerhouse, and no one had ever imported a transistor radio from Japan, Korea, or China.

Based on what you would have known in 1950, your plan would have made the airport too small and the train station too big. Since you would assume that married women worked at home, you would have designed homes with one-car garages. You would assign too much land to manufacturing and not enough to white collar jobs. You would never have imagined home offices.

In lieu of accurately predicting the future, planners use a technique they call visioning in which they ask people to imagine what they would like their city to look like in the future. They then try to plan for that city.

Visioning has numerous flaws. Most obviously, the people doing the visioning still have no special knowledge of the future. So it is most likely that their visions will really be based on a nostalgic view of the past.

Second, visioning results in a mandate for coervice planning. After all, if you can imagine the best possible future for your city, you would not want to risk that future to the uncertainties of the free market or people’s short-term preferences.

Finally, the people writing the vision do not represent all of the people who will live in that future. If they make mistakes, the cost of those mistakes will be shared with others, so they have little incentive to try to get it right.

For all these reasons, visioning is the wrong solution to planners’ inability to predict the future. Instead, in many cases, it just become one more excuse for planners to impose their own nostalgic ideas on their cities.

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Reprinted from The Antiplanner