Evaluating transport demand management interventions

Theoretical approaches to evaluating public policy initiatives seek to account for the effect of factors external to the initiative which could impact on the outcome of that initiative. The application of this approach within the transport sector is relatively new despite current government Department for Transport guidance advocating its use. Nottingham is the first City in the UK to implement a Workplace Parking Levy (WPL) which places a levy on private non-domestic off street parking provided by employers. The scheme acts as a transport demand management measure with the revenue hypothecated for funding a package of transport improvements. This paper analyses the application of a theoretical evaluation approach, using the example of the Nottingham WPL package as a case study. The analysis includes a logic map based on stakeholder consensus and literature, explaining how the package is expected to meet its stated objectives. The paper concludes that a combination of two theoretical approaches, ‘Theory of Change approach strengthened by elements of ‘Realistic Evaluation, as an appropriate framework for evaluating transport interventions and that this has established a plausible model for change and expected outcomes and impacts for the Nottingham WPL Package. Additionally, it concludes that the available data supports the validity of the established Theory of Change for the Nottingham WPL package with regards to shorter term outcomes. This will be invaluable to any authority which chooses to pursue a similar approach.