norman w. garrick transportation forecasting what is it? transportation forecasting is used to...
Post on 21-Dec-2015
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Norman W. Garrick
Transportation ForecastingWhat 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’
Norman W. Garrick
Transportation ForecastingWhat 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.
Norman W. Garrick
Transportation ForecastingScenario 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’.
Norman W. Garrick
Transportation ForecastingScenario Planning Example
For example, transportation forecasting models can be used to answer the following question
What will a region look like if we develop1. Based mostly on highways with no land use
control2. Based mostly on transit system with land use
control that favor transit oriented development
Norman W. Garrick
Traffic Congestion in Chicagoland 1996
Thanks to Lucy Gibson, Smart Mobility
Norman W. Garrick
Traffic Congestion in Chicagoland 2020 Scenario 1 (Business as Usual)
Thanks to Lucy Gibson, Smart Mobility
Scenario 1Business as usual = Predict and Provide
More highwaysLittle investment in Transit
More sprawlMore decay in cities
Norman W. Garrick
Traffic Congestion in Chicagoland 2020 Scenario 2 (Transit Oriented
Planning)
Thanks to Lucy Gibson, Smart Mobility
Scenario 2Transit Oriented Planning
Less highwaysMore Transit
Develop in CentersRevitalize Cities
Norman W. Garrick
Transportation ForecastingOther 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?
Norman W. Garrick
The Four Step Model
• Trip GenerationEstimates the number of trips from given origins and destinations
• Trip DistributionDetermines the destination for each trip from a given origin
• Mode ChoiceDetermines the mode choice for each trip
• Route AssignmentDetermines the specific route for each trip