In the “economic” part of the module, we introduce the crucial economic problem of scarcity, and its relevance to transport issues. We describe the characteristics of free and planned markets, and how these resolve the basic questions of what, how and for whom goods and services should be produced. We then examine the underlying economics of the market in terms of demand and supply. The economic costs of mobility and how these are accumulated are then examined, before we study the economists’ model of perfect competition and then, from this hypothetical “ideal”, we move to consider government intervention in the form of transport subsidies and regulation that are needed in reality to provide society with the level of accessibility it requires in a sustainable and equitable way.The “appraisal” part explains the need for appraisal procedures in the private and public sectors. We examine the business cases required to take decisions on public transport investments in the UK. We present WebTAG, the UK public appraisal system used to generate the evidence required in the transport business cases. We analyse the content of transport studies produced according to WebTAG guidelines, with particular focus on calculation of benefits for transport users and social cost benefit analysis. Finally, we examine the potential wider impacts of transport investments on the economy, the environment and society, and discuss the necessary conditions to foster positive welfare impacts