URBAN FREIGHT TRANSPORT POLICIES: JOINT ACCOUNTING OF NON-LINEAR ATTRIBUTE EFFECTS AND DISCRETE MIXTURE HETEROGENEITY

This paper jointly investigates non-linear attribute effects and discrete mixture heterogeneity. The research context relates to urban freight transport policy evaluation. The paper adopts an agent-specific perspective. The often unforeseen and undesired results deriving from urban freight transport policy implementation have induced many researchers to call for an in-depth analysis of specific agents' preferences. However, the structural lack of appropriate data has hindered investigations at such a detailed level. This paper contributes to bridging this data and knowledge gap by: constructing an original data set; testing for non-linear effects in attribute level variations; investigating the presence of inter and intra-agent heterogeneity; jointly exploring non-linear attribute effects and intraagent heterogeneity. The results obtained underline the relevance of intra-agent preference heterogeneity and non-linear effects of attribute variations. More in detail, the paper detects two classes of agents with substantially different preferences with respect to the possible policy interventions. Non-linear sensitivity suggests policy makers should carefully consider the effects induced by the specific status quo level for policy relevant attribute variations. Intraagent discrete heterogeneity implies different willingness to pay measures for given policy changes. The presence of both non-linear effects and intra-agent heterogeneity suggests policy makers to explicitly consider the status quo level that is to be changed while, at the same time, contemplate differentiated reactions deriving from the implementation of a urban freight policy change. In conclusion, the paper underlines the need for rigorous ex-ante policy analysis if the correct policy outcomes are to be estimated with an adequate level of accuracy.