This report investigates the optimal (best overall, taking into account all benefits and costs) transportation emission reduction strategies. Current evaluation methods tend to undervalue mobility management (also called Transportation Demand Management or TDM) strategies that increase transport system efficiency by changing travel behavior, due to biases that include (1) ignorance about these strategies; (2) failure to consider cobenefits; (3) failure to consider rebound effects of increased fuel economy; (4) belief that mobility management impacts are difficult to predict; (5) belief that mobility management programs are difficult to implement; and (6) belief that vehicle travel reductions harm consumers and the economy. More comprehensive and objective analysis tends to rank mobility management strategies among the most cost-effective emission reduction options. This report describes ways to correct current planning bias so mobility management solutions can be implemented to the degree optimal.