Whatcom Transportation Model
Whatcom Council of Governments (WCOG), as the designated Metropolitan Planning Organization (MPO), is responsible for the development and maintenance of the travel demand model for the region. The transportation model simulates vehicle and truck flow on regional highways and forecasts future demand using a four-step process (Trip Generation, Trip Distribution, Mode and Assignment). The software platform used in the development of the travel demand model was emme/2. However, the travel demand model software was converted to TransCAD in 2007 due to its comprehensive modeling tools and seamless GIS integration.
2008 Household Survey
Currently, WCOG is selecting a consultant to conduct a household travel survey for the regional travel demand model update to estimate the travel patterns in the region. The process to update the current model to a 2008 base year will begin this summer.
The household travel survey will be used to estimate trip rates, trip length frequency distribution, modes of travel, and time of day among other travel behavior characteristics needed in the travel demand model. The results of the survey as well as the 2008 base year demographics, transportation network, and counts will be used to calibrate and validate the travel demand model. Afterwards, the model will be used for various applications and products such as the regional transportation plan.
The travel demand model can be used for scenario testing by adjusting variables within the model and comparing the results. Examples of variable that can be used for sensitivity testing are household, employment and the transportation network.
Uses of a regional transportation model
Examples of the results in the model that can be used when comparing scenarios are vehicle miles travelled, vehicle hour travel, volume, and travel time. If the transportation network or land use is modified, the results can be compared between scenarios and someone in a policy role can determine the impacts on vehicle miles travel or any other outputs from the travel demand model.
In addition, the outputs from the travel demand model can be use for further analysis with other tools such as traffic operations models and air quality models.