In an ever-expanding world, impacts of human activity on the global environment are inevitable, and biodiversity is being lost at an increased rate. One major threat to biodiversity resulting from human activity is infrastructure development. The construction of roads and other linear transport infrastructure leads not only to the destruction of habitats, but has continuous long-term impacts on populations and biodiversity, including the introduction of edge and barrier effects, isolation of populations, facilitation of invasive species dispersal, mortality of individuals in vehicle collisions, and disturbance of animals through noise and light pollution. However, roadsides can also have positive effects on biodiversity and have been found to constitute important habitats for some taxa, including rare and red-listed species. The view that roadsides may offer an opportunity to promote biodiversity is relatively recent, and while individual studies have quantified negative or positive impacts of roadside habitats on select species or under select management regimes, the grand picture of the importance of roadside habitats for biodiversity conservation remains unclear. This is undoubtedly linked to the fact that it is difficult to quantify these effects across taxa. However, to mitigate negative effects of roadside habitats and to facilitate positive ones, we need to gain a holistic view of the many factors that affect different taxa and understand the direction and magnitude of their effects on each taxon. Here, we aim to quantify the impacts of habitats related to transport infrastructure (HTI) on a range of taxa by carrying out meta-analyses. We take a multi-scale approach and focus not only on classical biodiversity measures such as mean species abundance, but additionally consider population-level processes by quantifying impacts on different life-history traits, contingent upon data availability. Results from the meta-analyses will be presented to give a global update of what has been found in the past 10+ years regarding positive and negative effects of factors related to HTI on all taxa with sufficient data, ranging from invertebrates to large mammals. One of our objectives is to enhance our understanding of the extent to which HTI can be beneficial for biodiversity conservation, the effects they have on population level-processes, and how these vary among species and road types. Indeed, what is beneficial to one taxon is not necessarily beneficial to biodiversity and ecosystem functioning. The results of this study are relevant for making decisions on road construction and roadside management, as they offer a multi-species perspective regarding impacts of HTI on biodiversity. Our study will also identify knowledge gaps in the literature that can direct future studies in road ecology.