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7 To start building a new scenario, the user provides a name for the desired scenario (Figure 5) and then identifies the planning program or plan of interest to the userâs agency or organization. These transportation-related policies, programs, plans, or investment projects will address one or more planning issuesâbased on a series of questionsâand various performance metrics. Step 1: Selecting a Program or Plan In Step 1, the user selects a program or plan. Programs and plans fall into five major categories, as shown in Figure 6, and include associated elements. Only one program or plan can be selected for a given scenario; there are 36 programs and plans. Hovering over a program element (without selecting it) allows users to view a brief description for reference (Figure 6). Additional details for each program element are also available and can be accessed via the upper-left menu of TFGuide (Reference > Programs). A user who seeks to evaluate methods for multiple planning programs or plans will need to evaluate each planning program or plan separately and then identify methods that can support multiple purposes (and provide additional benefit for the same cost). The ability to evaluate multiple planning programs or plans together within TFGuide may be considered as a future enhancement. Building a Scenario C H A P T E R 3 Figure 5. TFGuide scenario name.
8 Method Selection for Travel Forecasting: User Guide Step 2: Specifying Plan or Program Requirements In Step 2, the user provides details regarding the overall planning context of the program or plan for which the user is seeking analytical method recommendations. The user also must pro- vide additional details about the agencyâs planning area and make at least one selection within each requirement category: 1. General, including needed analytical rigor and regulatory issues. 2. Level of Detail, including demographic, geographic, network, spatial, and temporal. 3. Scope, including pricing policies, sensitivities, and the affected travel markets. TFGuide evaluates the requirements necessary to address the planning issue to help the user fully understand the planning context. Figure 7 presents elements within two of the requirement categories: The user then selects at least one element (but more are permitted) for each category. Most elements are open to multiple selections, allowing the user to identify that there is flexibility in Figure 6. Five major program and plan categories.
Building a Scenario 9 these requirements (e.g., for the temporal detail, a peak period and an hour may be selected if the user wants recommendations for both options). However, geographic and spatial details are constrained to one choice. These special elements use radio buttons instead of the multiselect checkboxes to indicate a single selection. Finally, the user is permitted to assign weights (from 1 to 5) to delineate the relative importance of the requirements that TFGuide will use to generate the recommendations. The higher the weight, the more important the requirement for selecting methods. If all elements are to be treated equally, then the user can select the default value of â1â for each element. As noted, users can hover over items (without selecting them) to reveal short descriptions; more detail can be found in the reference guides in the software tool or in the appendices to this user guide. Step 3: Specifying the Performance Metrics In Step 3, the user chooses the performance measures of interest to the agency. The performance measures should be limited to and associated with the planning program and plan for which the user is seeking analytical method recommendations. Performance measures have increased con- siderably in the past 10 to 20 years, and there are now hundreds of different performance measures in use across the United States. TFGuide groups 34 individual metrics into six major categories of transportation planning performance measures. Figure 8 presents the performance measure categories and the performance metrics for the first several categories. TFGuide specifies some measures by segment (e.g., person miles traveled by mode) when these measures could be more generalized (e.g., person miles traveled). This intentional specificity Figure 7. User selections for requirements. Special Note: The Sensitivities element is provided to identify which methods are sensitive to changes in these elements. For example, equilibrium assignment models are not sensitive to traveler demographics, but they are sensitive to highway operations. If a user wants to evaluate vehicle miles traveled based on traveler demographics, then TFGuide will recommend more detailed assignment methods that are sensitive to traveler demographics.
10 Method Selection for Travel Forecasting: User Guide facilitates more precise recommendations. As with previous steps, users can assign weights and access short descriptions associated with each item; these descriptions are also available in the reference guide included with the software tool and appendices included in this user guide. Step 4: Specifying Constraints In Step 4, TFGuide asks the user to specify the agencyâs budget limit and schedule for a given scenario (Figure 9). Nearly all planning or program efforts are constrained by money, time, and other factors. This specification can be updated on the menu of recommendations page and relative weights (from 1 to 5) can also be assigned. Step 5: Specifying the Agencyâs Current Methods in Use In Step 5, the user can choose to provide (or skip) details regarding current analytical methods and agency resources for transportation planning, modeling, and simulation. The information the user can provide is shown in Figure 10; descriptions of individual methods and resources appear when the user hovers over an individual method or resource. The current agency methods and Figure 8. User selection for performance measures and metrics.
Figure 9. User selection for budget and schedule. Figure 10. User selection for current agency methods and resources.
12 Method Selection for Travel Forecasting: User Guide resources that TFGuide can assess include analytical capabilities, such as assignment and micro- simulation, commercial vehicle, and travel demand models, in addition to expertise, hardware, software, and data. This assessment provides two valuable services to the user: ⢠Recommendations unique and specific to each individual agency, given the tools and methods currently available. ⢠An improvement plan to help the agency transition from older practices to newer and improved methods in a targeted and stepwise manner. TFGuide can provide more customized responses if the user answers additional questions about current methods. The appendices to this user guide (reference guides built into TFGuideâs menu) should help users unfamiliar with some methods. Users may also choose to run TFGuide without any background on their current methods and then refine it to produce a set of recom- mended methods that are based on enhancements to current methods.
