Habitat fragmentation due to transport infrastructure is receiving growing concern among ecologists and civil engineers. Much data has been gathered that gives evidence of the complex impact of infrastructure on wildlife and landscapes. Roads, railroads, and their traffic disrupt ecological processes; increase mortality in animals, lead to a degradation, loss and isolation of wildlife habitat, and cause a fragmentation of the landscape in a literal sense. Despite the quantity of empirical studies, it is still difficult to draw general conclusions or define impact thresholds that could guide evaluation work. The increasing public demand on mitigation and prevention of environmental impacts strongly requires the development of evaluation tools for civil engineers and ecologists to apply in the planning and construction of transport infrastructure. In this essay, I briefly review the scientific literature on the known ecological effects of transport infrastructure, with special focus on roads.