Improving transportation project evaluation by recognizing the role of spatial scale and context in measuring non-user economic benefits.

The usefulness of transportation project evaluation depends on the completeness of its benefit measures. Since transportation networks are intrinsically spatial, transportation improvement projects have spatial access and location characteristics that can lead to a variety of non-user economic benefits. Recent research has enabled us to better understand how spatial context and spatial heterogeneity play further roles in generating efficiency gains for non-users, in the form of productivity, income, and cost savings for both private and public sectors of the economy. This paper draws upon that body of research to expand our understanding of the means by which transportation projects can generate economic efficiency gains, and approaches needed to measure them. It covers topics beyond those captured by current definitions of "wider economic benefits," including additional sources of scale economies associated with freight distribution and connectivity, and further public and private sector economic gains enabled by environmental and social inclusion improvement. It points to ways that non-user economic benefits can be more comprehensively defined and better measured by recognizing their spatial scale, context, and threshold effects. It also identifies ways that current benefit measurement methods introduce unintended bias into transportation investment decision-making through omission and mismeasurement. The result is a case for a refresh of thinking about how we classify and recognize non-user economic benefits in transportation evaluation, and how we apply transportation planning and economic models to support their measurement. • Transport decisions biased when non-user benefits are ignored or mis-measured. • Non-user economic benefits depend on spatial access, proximity, or connectivity. • Spatial scale, context, and heterogeneity affect measurement of non-user benefit. • Benefits from freight density, virtual density, effective density, non-user cost. • Rigid travel modeling standards hold back non-user benefits. [ABSTRACT FROM AUTHOR]