The highly competitive nature of the transportation industry has produced significant demand for increased equipment efficiency. This has been manifested in attempts to increase carrying capacity whilst lowering running costs. While these factors remain at the forefront of trailer design, the dependence on steel as the primary material has limited the extent to which these goals are realised. The advantages associated with the use of fibre composite materials in automotive applications have been well documented, demonstrating that the substitution of steel with fibre composite materials greatly increases the scope for tare mass reduction. However, to fully utilise the advantages produced through the use of fibre composites, it is necessary to formulate a design philosophy that incorporates the selection of materials and the definition of acceptable performance of both the material and the trailer. This dissertation addresses this broad subject. Within this greater context, this study addresses the incorporation of fibre composite materials into semi-trailers, with the significant issues being divided into two areas: - The development of a design philosophy, intended specifically to address the application of fibre composites to semi-trailers. - The design, analysis and experimental validation of a new type of fibre composite trailer chassis, utilising the aforementioned design philosophy. This PhD project is a foundational study on the suitability of fibre composite materials in the heavy transportation industry, primarily focusing on a practical assessment of the potential for tare mass reduction. The work presented in this dissertation is seen to provide a basis for fibre composite trailer design, in addition to a foundation upon which further investigation into this field can be made. The major outcomes of this project include, amongst others: - The definition of significant load cases and trailer classifications · The development of a design philosophy suited specifically to FRP semi-trailers - The establishment of selection criteria which identifies appropriate FRP materials for use in this application - The development of a new type of FRP chassis for a flatbed semi-trailer - Validation of the design philosophy through experimental testing - Affirmation of the potential of FRPs in application to flatbed semi-trailers