Topics

• The Big Picture
  • Types of Models
  • Decisions on Approach
  • Transition Paths
  • End Users
• Model Input
• Model Development
• Model Application

The Big Picture

“Transportation planning can appear to be a complex and bewildering process when first encountered.”¹ 

Since the basic premise of transportation planning is to answer questions about future travel, it is appropriate for visitors to this Travel Forecasting Resource to understand the general transportation planning process.  This process develops information to be used in:

• making decisions about future development; and
• assessing the potential impacts on the transportation system. 

Typical transportation plans involve forecasts of travel patterns under some future scenario.  Scenarios include changes in transportation supply, like the introduction of new passenger rail service in a corridor or the addition of a tollway, or changes in transportation demand, like future growth in population or employment or adjustments to land use and development policies.  Although the word ‘forecast’ implies a future scenario, planners use estimates of travel for many different timeframes to assist decision makers with the transportation planning process. Transportation planning is multi-faceted and the subject of many other websites and resources.  Because travel forecasting has become such a complex, yet essential function of planning, this website, the Travel Forecasting Resource, is devoted solely to the subject of travel forecasting and its critical affect on planning outcomes. 

Travel forecasts represent the estimation of the demand for travel resulting from development plans combined with anticipated configurations of roadways, transit systems, tollways, freight facilities and transportation terminals.  In addition to measuring impacts on various transportation facilities, forecasts are used to evaluate various land use scenarios and patterns, quantify impacts on air quality standards and identify effectiveness of  pricing and demand management strategies- just to name a few. 

Simply stated, travel forecasts are generated by travel models.  Travel models are mathematical equations that compare land use and the corresponding population, employment and other activities associated with it to the transportation system to estimate demand for travel.  Travel demand occurs as a result of thousands of individual travelers making individual decision on how, where, why and when to travel¹.  These decisions are affected by many factors such as characteristics of the person making the trip, characteristics of the person’s household and trip destination, details related to the transportation facilities and modes available to the person making the trip, route options for the person’s trip and so on.  Mathematical relationships are used to represent (model) human behavior in making these choices. Models require a series of assumptions in order to work and are limited by data available to make forecasts.[1]

State Departments of Transportation, Metropolitan Planning Organizations (MPO), Local Governments and other transportation providers rely on travel forecasts to assist in the development of transportation plans to accommodate, evaluate and prioritize mobility needs within their various jurisdictions.  In fact, MPOs are required by law to maintain these plans and travel forecasting is an integral part of this work.  Travel forecasting models are used to estimate how urban growth, proposed facilities and the associated operational investments and transportation policies will affect mobility and the operation of the transportation system. Forecasts derived from these models enable policy makers to make informed decisions on investments and policies relating to the transportation system. In addition, MPOs in federally designated air quality nonattainment or maintenance areas have been given a central role in determining whether their regional transportation plans and programs conform to State Implementation Plans for meeting national air quality standards. Travel forecasting models play a principal role in this process as well.[2] 

In summary, this website exists to provide transportation planners and other stakeholders in the transportation planning field an opportunity to understand the many types of models that exist, identify the modeling approaches that best meet their needs, determine the transition path(or paths) to move their agency’s travel models further along the state of the practice-state of the art continuum as warranted by jurisdictional stakeholder concerns and provide a wealth of examples and resources along the way.

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