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Massive Uncertainty

Massive Uncertainty

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Massive Uncertainty

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  1. Massive Uncertainty Dr. Richard de Neufville Professor of Systems Engineering and Civil and Environmental Engineering Massachusetts Institute of Technology Airport Systems Planning & Design / RdN

  2. Massive Uncertainty • Objective: To present realistic context of forecasting exercise • Topics • Evidence • Consequences Airport Systems Planning & Design / RdN

  3. Causes of Uncertainty • Underlying variability of phenomenon • Difficulties in measurement or estimation • Unforeseen or “unpredictable” circumstances • Limits to valid measurement • for example: behavioral patterns Airport Systems Planning & Design / RdN

  4. Evidence 1. Simple Physical Systems 2. Overall Traffic 3. Local Traffic (Worse) 4. Other Operations Airport Systems Planning & Design / RdN

  5. Ratio of Real Costs to Estimated Costs for Airport Projects Costs expressed in constant dollars Median ~= 1.25 Percent of Occurrences Real/Estimated Cost Ratio Airport Systems Planning & Design / RdN

  6. Cost Growth for Various Projects 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Ratio of Actual to Estimated Cost DOD60 HWAY WATER BLDNG DOD50 ADHOC MAJOR ENRGY NASA NASA AVG St.Dev. CONST SAT mg Airport Systems Planning & Design / RdN

  7. NASA Projects Cost Growth 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Ratio of Actual to Estimated Cost HST GLL UARS GRO COBE MGL MOBS LSAT EUVE ERBE AVG St.Dev. Airport Systems Planning & Design / RdN

  8. Forecasting Errors Nature of Traffic Type of Traffic Percent Error which is Exceeded Half the Time after Each year One Year Two Years Three Years Four Years Five Years Six Years International US Domestic Passengers Pax-Miles Average Passengers Pax-Miles Average 8.0 7.2 7.6 2.9 2.9 2.9 10.9 10.9 10.9 6.2 6.0 6.1 14.0 13.8 13.9 11.2 10.6 10.9 14.0 15.7 14.9 14.1 14.5 14.3 15.1 16.7 15.9 18.3 18.3 18.3 15.8 19.5 17.6 20.4 21.8 21.1 Average Errors in the Forecasts of Air Traffic of the U.S. Federal Aviation Administration, 1958-71 Airport Systems Planning & Design / RdN

  9. FAA Forecasts Compared with Actual Data (% Difference) Review of the FAA 1982 National Airspace System Plan Airport Systems Planning & Design / RdN

  10. Forecast vs. Actual International Pax in Japan Airport Systems Planning & Design / RdN

  11. Forecast vs. ActualInternational Pax to Japan Airport Systems Planning & Design / RdN

  12. Forecast vs Actual International Pax in Sydney Airport Systems Planning & Design / RdN

  13. ACTIVE GENERAL AVIATION AIRCRAFT 1980 FORECAST Airport Systems Planning & Design / RdN

  14. ACTIVE GENERAL AVIATION AIRCRAFT 1985 FORECAST Airport Systems Planning & Design / RdN

  15. ACTIVE GENERAL AVIATION AIRCRAFT 1990 FORECAST Airport Systems Planning & Design / RdN

  16. ACTIVE GENERAL AVIATION AIRCRAFT 1998 FORECAST Airport Systems Planning & Design / RdN

  17. Summary and Recommendations • Summary • Forecast Errors have been large • Likely to continue • Recommendations: • Expensive Forecasting is cost-ineffective • Use general trends • ...With large ranges • Flexible Approach to Planning!!! Airport Systems Planning & Design / RdN