Issue 5 Evil Winter 2001/02
Raw and Processed Data
In April 2001, the Fund for the City of New York released a report that quantified the smoothness of the streets of New York.1 The Fund hired a firm that specializes in measuring the profiles of highways and airport runways to gather data on approximately 670 miles of the city's streets chosen at random. The New York street profiles were measured by a car which had a laser scanning device known as a profilometer attached to its side. The profilometer scans the ground and gets a reading every 0.011 inches when the car is driven at 20 mph.
The raw data, accurate to a thousandth of an inch, was then
converted into two standard indices: the International Roughness
Index (IRI) developed by the World Bank in the 1970s to measure
road roughness, and the Bump Index developed by Boeing to evaluate
runways for takeoff and landing. The World Bank provides a
computer program that will process the raw data and generate the
Roughness Index. The IRI indicates the total accumulated deflection
of the suspension of a theoretical car per distance traveled.2
Boeing's Bump Index measures the ratio of the bump height to the
bump length. A Bump Index of above 1.0 on a runway is considered
dangerous for planes taking off or landing.
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© 2002 Cabinet Magazine