Blake Boulton and Monika Balicki of WMS Engineering present two Excel-based drainage tools developed through ADB-supported work on climate-resilient road standards in Timor-Leste: a cross drainage and swale sizing tool and a culvert blockage screening tool. They set out why road drainage fails in steep, high-rainfall settings, from design standards that predate climate change to rainfall records that miss the short, intense storms that size culverts. They walk through how the tools work, covering the design rainfall basis, climate change as a user-selected setting, a seven-factor blockage assessment, and the culvert and swale sizes and checks the sizing tool returns. They close with the case for keeping the tools simple and open, and what the tools do not replace.