The construction and operational phases of national road schemes have the potential to impact on the surface and groundwater quality and quantity if sufficient protection is not provided. This is of particular importance in vulnerable areas such as karstified limestone, where the bedrock aquifer is more susceptible to pollutants as pathways are exposed on the surface. This research project consists of a review of the different geological conditions encountered in Ireland, an evaluation of the performance of different road drainage systems, and the development of design guidelines for different drainage systems suitable for the different geological, hydrogeological and hydrological situations in Ireland.