Indicators for Sustainable Transportation Planning
There is an ongoing debate worldwide about the indicators that policy makers should use to evaluate progress toward sustainable transportation systems. In general, studies of indicators lack an overall normative framework that allows decision makers or the public to make sense of the many overlapping and partial measures. A statewide urban growth model for California was run iteratively with the California statewide travel model to evaluate major transportation scenarios, such as freeway widening and high-speed rail. In addition, transportation and land use policies intended to provide more affordable housing accessible to jobs, widespread habitat protection, and strong reductions in greenhouse gas emissions were evaluated. This model provides many performance measures for travel, economic welfare and equity, rents paid, energy use, greenhouse gas emissions, vehicular air pollution, and habitat loss. A framework for interpreting these data on the basis of recent advances in the theories of well-being for individuals and nations is proposed. This theoretical framework for evaluating the model outputs used in planning also applies to the analysis of the empirical indicators used to track actual outcomes.