Maui MPO maintains the Maui Travel Demand Model to provide travel information that aids in planning for regional transportation improvements. A model update completed in 2021 includes current (2019) and projected (2025, 2030, and 2045) transportation demand on the island of Maui using TransCAD modeling software. For technical users with TransCAD software, to access the Travel Demand Model click here or view the User Report.
The Model Update Report
How does a travel demand model work?
Traditionally, an approach known as the “four-step process” has been used for regional transportation planning analysis. As its name implies, this process has four basic phases: 1. Trip generation (the number of trips to be made); 2. Trip distribution (where those trips go); 3. Mode choice (how the trips will be divided among the available modes of travel); and 4. Trip assignment (predicting the route trips will take). By looking at these four areas, we can answer the following questions: How many trips will people make? Looking at land use characteristics (i.e. how we use land in our region) is the main way to figure out trip generation rates. This is because factors like the number and size of households, automobile ownership, types of activities (residential, commercial industrial, etc.), and density of development all drive how much travel flows from or to a specific area within the region. For simplicity, a geographic unit called a transportation analysis zone (TAZ) is used to create trip generation rates for the region.
Where will jobs and people locate?
Once the model generates a certain number of trips from each TAZ, it needs to determine to which zone each trip goes. This is called trip distribution and the analysis involves a sophisticated process for weighting the “attractiveness” of each TAZ based on the number of attractions it has and the travel time from other TAZs. This step leads to a picture of origin and destination points within the region and how many trips are going between each pair of TAZs.
How will people travel?
Mode choice shows which mode people use to travel between their origins and destinations. That is, whether people take transit, their own car, or a carpool to and from work or another destination. A complex sub-model has been created for determining the modal choice, and is based both on certain assumptions about transit capacity, schedules, and fare levels and on real-world observations of how, when, and where people use transit. What routes will people take? Trip assignment determines the routes people will take from start (origin) to finish (destination). Generally, the computer assumes everyone will take the quickest route to their destination. To compute route selection requires all kinds of information regarding actual or predicted congestion levels, road conditions, transit schedules and fares, traffic signal systems, etc.
How do we know the model predicts reasonable trips?
Once the four steps are completed, the model provides planners with a picture of existing travel patterns. The results are then given a reality check. Modelers check with planning staff to make sure the numbers make sense, and cross-check how well the model predicts current “observed” data, such as park-and-ride utilization and highway vehicle traffic counts. This “checking” is called a validation.
What can the model tell us?
Travel demand model results can assist decision makers in making informed transportation planning decisions. The results from the model provide users with forecasted highway volumes for roadways with functional classes of minor arterial and above.
(FAQ adapted from Virginia DOT)