These comprehensive technical guides establish a unified framework for the planning, design, and maintenance of road drainage systems across Australia and New Zealand. They provide rigorous instructions for managing stormwater runoff, covering everything from hydrological analysis and flood estimation to the engineering of surface and subsurface networks. Key priorities include ensuring road user safety, mitigating environmental impacts on fauna and water quality, and protecting infrastructure from scour and erosion. The documents also address the complexities of climate change, tidal influences, and debris management to maintain long-term asset resilience. By integrating  ...