BACKGROUND

As a concept, induced demand is increasingly being considered by transportation practitioners at state departments of transportation (DOTs). Induced demand is challenging and intersectional, 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.