Introduction & background The appraisal of new transport infrastructure relies heavily on the ability of transport economists to accurately predict the demand for alternative transport options, as well as the ability to correctly identify and monetarise additional economic costs and benefits associated with each competing proposed option. Unfortunately, despite decades of research, the forecasting of demand for transportation projects, as well as the application of cost-benefit analysis to such projects has resulted in several spectacular failures. This PhD will study whether the systemic failure of transport appraisal may in part be explained by how transport studies are being conducted, and in particular how current research tends to by and large still examine different aspects of travel behaviour as if they are separate decision contexts, for example what mode is selected is treated as a separate choice to what route is taken.
Aims and Approach This PhD will make use of advanced choice modelling techniques and will test the impact of assumptions relating to the independence between different decision contexts. The key hypothesis to be tested is whether economic appraisal undertaken in this manner may be in violation of one of the basic tenets of micro-economic theory as related to demand forecasting, namely preference or market seperability. Demand forecasting, as described under micro-economic theory, requires that if demand for one market is to be studied in isolation, then the preferences of individuals operating in that market must be separable from other markets. Numerous examples arise that would question that assumption in the transportation context. Firstly, transportation decisions may be made with both short term and long term goals in mind. For example, the mode one takes to work is unlikely to be independent of where one lives, whilst the transportation options available may be defined by where one lives. Hence, longer term residential location choices may impact upon short term transportation travel patterns. Second, transportation is a derived demand insofar as individuals are assumed to travel so as to partake in some activity, as opposed to travelling simply for the sake of travelling. If such an assumption is true, then one cannot separate out transportation demand from the demand for all other potential activities. Thirdly, transportation demand is defined not just in terms of preferences for various alternatives, but also in terms of several constraints faced by individual decision makers, including both time and monetary constraints. The research conducted in this PhD will test the validity of these assumptions in a number of empirical contexts and will develop techniques that more accurately reflect the links and inter-dependencies between choices in different contexts. Crucially, the work will go beyond current research in activity based modelling, which recognises links between individual day to day decisions, by acknowledging inter-dependencies between somewhat different choice contexts, for example transport decisions and household energy choices.
Impact of Research This PhD research will lead to a new understanding of how different choice dimensions inter-act and depend on each other. It will provide insights into how to model these links, and empirical evidence of the impact of failing to do so, for example on cost benefit analysis for infrastructure and policy schemes.
Training The student would be encouraged to attend transport modelling modules at the Institute for Transport Studies, as well as choice modelling courses run by the Choice Modelling Centre in Leeds and in London. The student would also be encouraged to present his/her work at international conferences.
Partners and Collaborators This PhD would be co-supervised by Professor John Rose from the Institute for Choice at the University of South Australia, a key international partner of the Choice Modelling Centre at the University of Leeds, and also a visiting professor at the Institute for Transport Studies at the University of Leeds. Professor Rose will also host the student during a 2-3 month research stay in Australia, a visit that will be funded by the Institute for Choice, and which will greatly increase the exposure of the student to international research.
Entry requirements/necessary background:
A first class (or equivalent) undergraduate degree related to mathematics or statistics from a reputed university is desirable. Candidates with an upper second class (or equivalent) degree from excellent universities will also be considered, especially if the candidate has a Masters degree and/or practical experience in a highly relevant area. Experience of mathematical modelling and/or computer programming skills is also desirable.
Please visit our LARS scholarship page for more information and further opportunities: https://www.environment.leeds.ac.uk/study/postgraduate-research-degrees/lars-scholarships/
Hensher, D.A., Rose, J.M. & Greene, W.H. (2015), Applied Choice Analysis, second edition, Cambridge University Press.
Ortúzar, J.d.D. & Willumsen, L.G. (2011), Modelling Transport, 4th Edition, Wiley.
Train, K. (2009), Discrete Choice Methods with Simulation, second edition, Cambridge University Press.