1. Norman W. Garrick Transportation Forecasting What is it? Transportation Forecasting is used to estimate the number of travelers or vehicles that will use a given transportation facility in the future The conventional approach to transportation forecasting is based on what is commonly know as the ‘four step model’

2. Norman W. Garrick Transportation Forecasting What is it used for? Transportation forecasting models have often been used in a ‘predict and provide’ mode to determine the highway capacity needed in response to predicted growth in traffic volumes. Often, in this case, the full impact of changes in land use is not properly taken into account and the resulting induced traffic is over looked.

3. Norman W. Garrick Transportation Forecasting Scenario Planning If transportation forecasting models are adjusted to properly account for the impact of changes in land use patterns they are useful for evaluating the implications of different transportation choices. In other words, they can be used for so called ‘scenario planning’.

4. Norman W. Garrick Transportation Forecasting Scenario Planning Example For example, transportation forecasting models can be used to answer the following question What will a region look like if we develop 1.Based mostly on highways with no land use control 2.Based mostly on transit system with land use control that favor transit oriented development

5. Norman W. Garrick Traffic Congestion in Chicagoland 1996 Thanks to Lucy Gibson, Smart MobilitySmart Mobility

6. Norman W. Garrick Traffic Congestion in Chicagoland 2020 Scenario 1 (Business as Usual) Thanks to Lucy Gibson, Smart MobilitySmart Mobility Scenario 1 Business as usual = Predict and Provide More highways Little investment in Transit More sprawl More decay in cities

7. Norman W. Garrick Traffic Congestion in Chicagoland 2020 Scenario 2 (Transit Oriented Planning) Thanks to Lucy Gibson, Smart MobilitySmart Mobility Scenario 2 Transit Oriented Planning Less highways More Transit Develop in Centers Revitalize Cities

8. Norman W. Garrick Transportation Forecasting Other Questions Transportation forecasting models, with proper accounting for land use impacts, can be used to answer specific questions such as What is the effect of congestion charging? What is the effect of parking control and transportation demand management? What is the effect of more concentrated development?

9. Norman W. Garrick The Four Step Model Trip Generation Estimates the number of trips from given origins and destinations Trip Distribution Determines the destination for each trip from a given origin Mode Choice Determines the mode choice for each trip Route Assignment Determines the specific route for each trip