ABSTRACT
The transportation literature has long addressed issues of social equity (hereinafter simply equity) in the provision of transportation infrastructure mainly in relation to accessibility, travel costs, and mode choice. In some cases-most commonly in public transit-the investment’s declared intent is to ensure greater equity or an improved equity distribution. In general, transportation improvements distribute nonuniformly over space, implying that they affect diverse populations disproportionately. Equity cannot, however, be regarded as a pure externality, equivalent, for example, to the environmental degradation following from a road investment that increases traffic volumes and thus emissions. For this reason, equity effects are discussed in this part and not in Part D, which focuses on the major externalities produced by transportation investment projects.
