Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles, Volume 1: Executive Summary (2018)

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7 Framework for Planning and Modeling CAVs A framework for forecasting CAVs includes five elements: • Data, • Planning context, • Modeling, • CAV adoption timeline, and • Communication of uncertainty. The first three elements—data, planning, and modeling—combine to create a forecasting environment. The typical planning process includes developing a vision for transportation in a region, setting goals and performance measures as targets, collecting data, building models from the data, and using models in either a predictive or an exploratory mode to evaluate alternative transportation investments. The fourth element concerns the timeline within the planning horizon and the level of advancement and adoption of automated transportation technologies. The timeline in Figure 1 indicates that data are collected in the past and planning occurs in the present. The CAV adoption timeline arrow indicates that an agreement needs to be made on the level of adoption/advancement of CAV technology—and the rate of adoption of the technology— over the planning/modeling timeline period. No assumed time period is indicated in the figure. Figure 1. Framework for CAV planning and modeling.

8 Updating Regional Transportation Planning and Modeling Tools to Address Impacts of Connected and Automated Vehicles The last element, communication, involves the need for the analyst to convey the level of uncertainty associated with the model results to decision makers and stakeholders. A situation that analysts commonly face in using this framework is a de facto interpretation of results as predictive. A better method is to determine at initial project scoping whether the analysis is going to be based on predictive, data-supported modeling or on exploratory techniques, which should not be taken as a prediction.