The logistics and transport industry places a heavy load on the environment, causing various harms such as air pollution, global warming and resource depletion. The logistics and supply chain management literature assigns the largest share of responsibility for alleviating such harms to two supply chain actors: shippers (i.e., logistics buyers) and logistics service providers (LSPs), which motivated focusing on them in this thesis. Specifically, the purpose of this thesis is to investigate the engagements of shippers and LSPs in different green logistics practices (GLPs) throughout the logistics purchasing process, and to propose improvements for such engagements by their interactions.

Three research questions drive this investigation. The first question handles comparing the drivers (i.e., institutional pressures) for shippers to purchase GLPs and for LSPs to provide them—to reveal how this ‘one-tier network’ is driven as a whole. The second question aims to describe how shippers and LSPs engage in the different GLPs throughout the logistics purchasing process (across its four phases: request for proposal, negotiations, contracting and execution) and why such engagement takes place as it does. The third question aims to propose improvements for shippers’ and LSPs’ engagements in the different GLPs throughout the process—by enacting different degrees of interactions (cooperation vs. collaboration). A methodological triangulation approach is used to answer these questions, based on five papers that are extracted from three studies: a single case (shipper-LSP dyad), a multiple case (3 shippers, 5 LSPs) and a survey (169 shippers, 162 LSPs).

The findings reveal a lack of direct regulatory, market and competitive pressures on shippers to purchase GLPs. These are compared to existing (yet insufficient) regulatory pressure, effective market pressure and emergent competitive pressure on LSPs to provide GLPs. The findings also reveal gaps between the actors’ purchasing-providing engagements in GLPs across the purchasing process, which followed three patterns: steady & wide, steady & narrow and emergent. Distinct GLPs are associated with each pattern, and detailed explanations are presented for these associations based on the characteristics of each GLP . Further, the findings propose paths to improve the actors’ engagements in GLPs across the process, based on the gap pattern for each GLP and the degrees of shipper-LSP interactions required for it (cooperation vs. collaboration).

This thesis contributes to the body of knowledge through systematically incorporating a trilateral actor-, phase- and GLP-specific distinction into the green logistics purchasing discussion. Also, it transcends the descriptive (and general) level of analysis of shippers’ and LSPs’ green engagements during the logistics purchasing process, by: (i) explaining why such engagements occur as they do and (ii) providing recommendations that could actually improve these engagements. Insights are offered to managers at shipper/LSP firms to assist them in modifying their purchasing/marketing strategies throughout the purchasing process with respect to specifically targeted GLPs. Insights are also offered to policymakers to set suitable regulations on both actors to support ‘greening’ logistics networks.