The objective of this research is to incorporate quantitative results from a range of STEPS projects to develop integrated, self-consistent and insightful scenarios of possible transportation futures. The quantitative models applied within this research will vary in complexity, but they are likely to be of two types: bottom-up or top-down. The bottom-up VISION model (from Argonne National Lab) is currently being applied to evaluate the introduction of AFVs Nationally and in California. A second potential bottom-up model is the MARKAL model. As the STEPS Program evolves, a top-down or economic model may also be incorporated to support scenario development (such as the NEMS, MINICAM, BEAR or AMIGA models, or a Systems Dynamics model such as HyDIVE).