BACKGROUND

As a concept, induced demand is increasingly being considered by transportation practitioners at state departments of transportation (DOTs). Induced demand is a complex phenomenon that is influenced by multiple variables, necessitating consistent analysis and transparency. DOTs are interested in understanding how induced demand impacts their planned investments and how those impacts might accrue at the local and regional network levels. It is not clearly understood in empirical analysis where induced demand manifests itself and how it undermines desired project outcomes for various project types. 

Recent attempts at analysis are the California Induced Travel Calculator (CITC), the Rocky Mountain Institute’s State Highway Induced Frequency of Travel (SHIFT) tool, and the Federal Highway Administration’s Geospatial Economic Multimodal Systems Modeling (GEMS). The CITC and SHIFT tools incorporate ranges of elasticity findings from different induced demand studies and project conditions but have several limitations for project-level analysis (for example, contextual factors or land use). GEMS may provide typologies to help identify influencing factors and mitigation options as alternatives to new lane miles. Research is needed to assist DOTs to better understand induced demand, especially at the project level, concerning their priorities, policies, funding decisions, and DOT options to respond to induced demand directly or indirectly.

OBJECTIVE

The objective of this research is to develop an induced demand assessment framework and a guide for DOTs to apply the assessment framework to policy and planning analysis. 

At a minimum, the research shall (1) define induced demand; (2) gather and evaluate data needed to develop the assessment framework; (3) pilot, validate, and test the assessment framework; and (4) communicate findings from the framework to build consensus.

TASKS

Phase I

Task 1: Review of Literature and Practice

1.1) Amplified Research Plan and Kick-Off Meeting - Within fifteen days of contract execution, the research team shall deliver the Amplified Research Plan for panel review and NCHRP approval. The research team shall participate in a project kick-off meeting arranged by NCHRP following the approval of the Amplified Research Plan.

1.2) Review of Literature and Practice – The research team shall review and summarize literature on induced demand effects and current practices for considering induced demand and define terminology. A memorandum shall be submitted in the first Quarterly Progress Report (QPR) documenting the research process and findings that include an annotated bibliography, summary of the literature and practice, definition of terms related to induced demand, and examples of practical applications.

Deliverables:

•        1.1) Amplified Research Plan and Kick-off Meeting with Summary Notes

•        1.2) Task 1 Memorandum – QPR 1

Task 2: Document Induced Demand Relationships and Develop Phase II Plan

The research team shall document known relationships between transportation improvements and vehicle travel demand, describe how effects may depend on spatial and temporal context, identify gaps in knowledge, and develop an Updated Phase II research plan to help fill gaps. The research team shall present findings to NCHRP at an in-person interim meeting. NCHRP approval of the interim report and updated Phase II Research Plan is required before work on subsequent tasks may begin.

Deliverables:

•        2.1) Draft Phase I Interim Report (containing the Task 2 memorandum) and Updated Phase II Research Plan

•        2.2) Final Phase I Interim Report and Updated Phase II Research Plan – QPR 2 

Phase II

Task 3: Data Gathering and Analysis

The research team shall gather and evaluate additional data to help fill in gaps in knowledge on induced demand and illustrate how effects may vary for different project types and contexts. The research team shall develop a task memorandum documenting process and results, including data sources, analysis methods, and key findings.

Deliverables:

•        3.1) Task 3 Memorandum – Preliminary Data Analysis – QPR 3

•        3.2) Task 4 Memorandum – Final Data Analysis – QPR 4

Task 4: Assessment Framework, Guide Outline, and Phase III Plan

The research team shall bring the knowledge gathered in the Phase I review and Phase II research into a common framework of information related to induced demand that can be applied in different transportation policy and planning contexts. The research team shall develop a detailed outline of a guide to induced demand and develop a plan for piloting this framework and draft guide. The research team shall present findings to NCHRP at a virtual interim meeting. NCHRP approval of the interim report and updated Phase III Research Plan is required before work on subsequent tasks may begin

Deliverables:

•        4.1) Draft Phase II Interim Report (containing the Task 4 memorandum) and Updated Phase III Research Plan

•        4.2) Final Phase II Interim Report and Updated Phase III Research Plan – QPR 5

Phase III

Task 5: Pilot Application

The research team shall test the assessment framework and draft guide outline with at least three sets of transportation agencies and propose revisions to full guide. The research team shall develop materials for each workshop and a memorandum summarizing the discussions. A pilot application report shall be submitted including description of pilot process, key lessons learned, and proposed revisions to final assessment framework and guide outline.

Deliverable:

•        5) Pilot Application Report - QPR 6

Task 6: Draft Final Guide and Research Products

The research team shall develop the draft guide to the induced demand assessment framework, as well as associated research products and implementation aids. The guide shall be developed as an NCHRP WebResource. 

            Deliverables:

•        6) Draft Guide as an NCHRP WebResource, draft Conduct of Research Report in Microsoft Word, draft presentation (with speaker notes summarizing the project in Microsoft PowerPoint, and draft implementation plan.

Task 7: Final Guide and Research Products

Following panel feedback and NCHRP approval, the research team shall Develop final versions of all deliverables. 

Deliverable:

• 7) Final Guide as an NCHRP WebResource, final Conduct of Research Report in Microsoft Word, final presentation (with speaker notes summarizing the project in Microsoft PowerPoint, final implementation plan, and a draft TRNews Highlight.