Airport Forecasting

NOTE: for HW, draw cash flow diagram to solve and review engineering economics

errata

• General Airport website: http://www.bluegrassairport.com/Master Plan Executive Summary: http://www.bluegrassairport.com/documents/AUG_21_WEB_Lexington_Airport_MP_Update_ExecSumm.pdfMaster Plan Appendix A (Forecasts): http://www.bluegrassairport.com/documents/LEX_Master_Plan_Appendix_A_Website.pdfFull Master Plan: http://www.bluegrassairport.com/documents/LEX_Master_Plan_Report_Website.pdf

• See first two pages of Appendix A

Forecasting Demand

• Essential to have realistic estimates of the future demand of an airport

• Used for developing the airport master plan or aviation system plan

Data used to predict future1. Airport service area

2. Origins and destinations of trips

3. Demographics and population growth of area

4. Economic character of area

5. Trends in existing transportation activities for the movement of people, freight, and mail by various modes

6. Trends in national traffic affecting future development

7. Distance, population, and industrial character of nearby areas having air service

8. Geographic factors influencing transportation requirements

9. Existence and degree of competition between airlines and among other modes of traffic

Estimates Needed

1. The volumes and peaking characteristics of passengers, aircraft, vehicles, freight, express, and mail

2. The number and types of aircraft needed to serve the above traffic

3. The number of based general aviation aircraft and the number of movements generated

4. The performance and operating characteristics of ground access systems

Forecasting by Judgement

• Delphi Method: A panel of experts on different subjects is assembled and asked a series of questions and projections which they take into account to determine a forecast

Trend Extrapolation

0

50000

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1970 1975 1980 1985 1990 1995 2000

Year PAX1970 1981281975 2593171980 2957801985 3407171990 36067019952000

375000390000

Top-Down ModelExtrapolate 1 and 2, multiply to get 3:

Statistical Abstract of the US Air Carrier FleetBTS # of Aircraft, …FAA aviation stats

Cross Classification Model• Cross Classification: examines the behavioral

characteristics of travelers• Travelers broken down into classifications based

upon these characteristics

• Based on the belief that certain socioeconomic characteristics influence the inclination for travel

• Market study performed to determine the travel characteristics of the individual groups

• By knowing the different groups’ travel patterns, forecasts can be made by projecting the patterns out

Factors

• Income• Occupation• Age• Type and location of residence• Education• etc…

Market Study

• Market Study method does NOT require complex mathematical relationships

• uses simple equations to generate a classification table or matrix

• Advantage: allows for discrimination between discretionary and non-discretionary travelers and the factors that influence both types

Non-discretionary = business traveler

Discretionary = vacationers

Multiple Regression

• Econometric Modeling: relates measures of aviation activity to economic and social factors

• Multiple Regression is used to determine the relationships between dependent variables and explanatory variables

Explanatory Variables

• Economic growth• Population growth• Market factors• Travel impedance• Intermodal competition

Regression Equations

• Linear Regression form:

Y = mx + b

• Multiple Regression form:

Yest= ao + a1X1 + a2X2 + a3X3 + … + anXn

Statistical Testing of Models

• Tests performed to determine the validity of econometric models

• The analyst needs to consider the reasonableness as well as the statistical significance of the model

Coeff. of Mult. Determination

• Coefficient of multiple determination, R2 : measures the variation in the dependent variable that is explained by the variation in the independent variables

• (e.g. R2 = 1.0 is perfect correlation)

• Equation:

R2 =(Yest - Yavg)2

(Y - Yavg)2

Coeff. of Mult. Correlation

• Coefficient of multiple correlation, R: measures the correlation between the dependent variable and the independent variables

• (e.g. R = 1.0 perfect correlation)• Equation:

R = (R2)1/2

Standard Error

• Standard error of the estimate: measure of the dispersion of the data points about the regression line and is used to establish the confidence limits

• Equation:(Y - Yest)2

m - (n+1)[ ]y est =

Equations for Trend Line

ENP POP Year (thousand) (thousand)1983 469 2501984 515 2601985 638 2721986 758 2741987 935 2871988 996 2961989 1140 3071990 1361 3171991 1479 3261992 1651 332

y = 134.59x + 253.93

R2 = 0.9872

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250 260 272 274 287 296 307 317 326 332

Microsoft Excel

Worksheet

Elasticity

• Elasticity: the percentage change in traffic for a 1% change in fare or travel time

• In the past, it was important

• Even greater significance today due to a deregulated industry

• fare wars• Hub and spoke system

Elasticity

• < -1, Elastic, people likely to change trip behavior

• E = 0, Perfectly Inelastic, no effect on trip behavior

• -1 < E < 0, Inelastic, less sensitive to price

qp

pq = ( )

Elasticity Example

Calculations

• Tourists:(-4000/2) (7/6000) = -2.33 < -1, Elastic

people likely to change trip behavior

• Commuters:(-1000/2)(7/7500) = -0.47 -1 < E < 0, Inelastic

less sensitive to price

qp

pq = ( )

Available forecasts

• FAA