During the year 2012 and the beginning of the year 2013, a group of European researchers and experts leaded by the ECTRI (European Conference of Transport Research Institutes) Thematic Group "Mobility" has worked on a research Initiative for ERTRAC (European Road Transport Research and Advisory Council) in the field of Land-use and transport interactions. The purpose was to identify the principal challenging topics for Europe in the coming years. The objective was also to provide elements of decision for policy makers in the fields of land use and transport planning. This paper summarizes the main conclusions of this document. The paper is divided into five parts. The second part proposes a brief overview of previous research in the field of LUTI in Europe and beyond. The third part explains the motivations of the paper. The fourth part discusses the research topics that have still to be investigated. The fifth part concludes the paper.