The objective of this research is to develop guidelines for travel forecasting practitioners to (1) assess the suitability and limitations of their travel forecasting methods and techniques to address specific policy and planning questions; (2) scope model development or improvements so as to attain the desired policy sensitivity within constraints such as institutional, budget, model development time, and resources; and (3) communicate limitations and any improvements to decision makers. The guidelines should be accompanied by a method selection tool that illustratively guides the practitioner through the selection of methods and techniques based on application needs, resource constraints, available data, and existing model structure. Planning and policy questions to be addressed, at a minimum, should include: (a) long-range planning, (b) performance-based planning, (c) safety, (d) project prioritization, (e) traffic detour planning/work zone analyses, (f) operational analyses, (g) managed lanes and toll revenue forecasting, (h) air quality and climate change analyses, (i) transit analyses, (j) walk and bike activity forecasting, (k) freight planning, (l) environmental justice analyses, (m) benefit-cost analyses, (n) economic impact analyses, (o) growth management analyses, (p) emergency management, (q) revenue analyses, and (r) other planning issues that models are asked to address. Each of the planning and policy issues identified should be tied to a set of “information needs” such as (a) level of temporal and spatial flows by market segment, (b) volume and speed outputs, (c) mode of travel, (d) travel cost, (e) travel time variation and reliability, and (f) other relevant performance metrics. The products of this research should be prepared for use by practitioners at state transportation agencies; metropolitan planning organizations (MPOs); transit agencies; and consultants who scope, develop, and apply travel forecasting models.
Accomplishment of the project objective will require at least the following tasks.
TASKS
PHASE I
(1). Conduct a review of existing literature and state of practice across MPOs, transit agencies, and DOTs and prepare a technical memorandum providing a detailed list of specific planning and policy issues that practitioners are asked to address along with the associated “information needs” to respond to them. (2). Review the literature and other available knowledge on forecasting methods and techniques in practice at a variety of agencies to generate data outputs to satisfy the “information needs” identified in Task 1. The review should be focused on existing methods and techniques and not on untested methods or techniques. Agencies considered should reflect a variety of characteristics including but not limited to: (a) small, medium, and large MPOs; (b) small and large transit agencies; (c) areas with rapid demographic shifts and stable demographics; (d) urban and rural areas; and (e) statewide models of varying complexity. The list of appropriate forecasting methods and techniques should consider a range of factors such as (a) trip-based or tour-based; (b) aggregate or disaggregate models; (c) from network microsimulation to meso/macroscopic assignment; (d) static assignment or dynamic traffic assignment or dynamic flow models; (e) integrated land use models or exogenous land use/demographic models; (f) qualitative or quantitative analysis; (g) behavioral or trend analysis; (h) commodity flow, logistics, or direct generation freight models; (i) from short-term to long-term choices; (j) from data synthesis to data collection; (k) longitudinal/lifecycle or cross-sectional models; (l) feedback/convergence mechanisms; (m) spatial and temporal aggregation level; (n) ordering of model components; (o) level of detail of the network attributes; (p) incremental or direct models; and (q) other forecasting techniques as appropriate. Information collected on each of the methods and techniques should include: (a) resource requirements such as cost and development time, (b) agency staff training and technical expertise, (c) data needs and cost, (d) computational resources, (e) variety of information produced, (f) scoping language used if a consultant developed the method or technique, (g) number of years the method or technique has been in use, and (h) the degree to which the method or technique has been validated. (3). Based on Tasks 1 and 2, prepare an interim report. The interim report should include: (a) the results from previous tasks, (b) a detailed description of the method that will be used to develop the guidelines, (c) a template for conveying capabilities and limitations of methods and techniques with respect to specific policy and planning questions, (d) an annotated draft outline for the guidelines, (e) the structure of the proposed method selection tool, and (f) an updated work plan for Phase II. The sections in the guidelines should be described in general along with the specification, description, design architecture, and proposed user testing of the method selection tool to be developed in Task 4. The guidelines should result in suggesting to the practitioner a bundle of methods and techniques that could be implemented together to respond to a prioritized menu of policy and planning issues. Factors to consider in suggesting methods and techniques should include, but not be limited to (a) staff expertise, (b) expected tradeoffs, (c) resource requirements, (d) relevant performance indicators, (e) development cost, (f) available data, (g) accepted risk, and (h) development time. The guidelines should form the conceptual basis for the method selection tool.
PHASE II
(4). Implement the approved Phase II work plan to develop a preliminary version of the guidelines and a preliminary version of the method selection tool. Additionally, provide the final version of the templates for conveying capabilities and limitations of the methods and techniques to decision makers and other users. (5). Develop final guidelines along with the method selection tool for travel forecasting practitioners to (1) assess the suitability and limitations of their travel forecasting methods and techniques to address specific policy and planning questions; (2) scope model development or improvements so as to attain the desired policy sensitivity within constraints such as institutional, budget, model development time, and resources; and (3) communicate limitations and any improvements to decision makers. The guidelines should describe the process, topical planning/policy issues, corresponding forecasting methods and techniques, information obtained from forecasting methods and techniques, the suitability of those techniques/methods, the quality of information, and provide references. The accompanying method selection tool should operationalize the guidelines and illustratively guide the reader through the selection of travel forecasting methods and techniques based on application needs, resource constraints, available data, and existing model structure (if any). The method selection tool should also provide a model specification report, including templates for scopes of services, based on user inputs of application needs and available data. The tool should be developed in a manner to enable future updates.
