Summary In order to establish a design rainfall and flow estimation methodology compatible with the Ethiopian environment and facilitate standard design practices in all road design works in Ethiopia, the Ethiopian Roads Authority (ERA) commissioned Louis Berger Group to prepare a road drainage design manual in 2002 under the credit of the International Development Agency (IDA). This technical note was prepared for the Ethiopian Roads Authority (ERA) following a brief review of the above manual published in 2002. The brief received from the ERA required me to review the above drainage design manual and to make any comments and recommendations. In preparing this technical note, I have read the ERA drainage design manual and various road drainage design manuals produced by other countries including USA, UK, Australia, Gahanna, South Africa, Uganda and Kenya. Clearly, in the time available, I was not able to carry out a complete technical review of the manual. However, I have used my local knowledge and past experience to review the manual with a critical eye, with the aim of identifying information and technology gaps, any uncertainties, misconceptions or missed opportunities. During the technical review it was found that the ERA drainage design manual contains most of the relevant technical information needed for the design of road drainage structures in Ethiopia. The design methodologies were adopted from the American Association of State Highway and Transportation Officials (ASSHTO), and the design papers were adopted from the Federal Highway Administration's Bureau of Reclamation Hydraulic Laboratory. Road development in Ethiopia has significantly accelerated in the last ... ... half of article ...... of tools available for predicting both rainfall runoff volume and peak discharge from both rural and urban catchments . However, it should be noted that no method is considered "right", while the rest are "wrong". However, to avoid confusion, a preferred method is recommended as good practice. Importantly, using more than one method can provide additional information on decisions to be made. This can be particularly useful in situations where the consequences of a drainage structure "failure" would be particularly severe (e.g. culverts and bridges). The comments and recommendations made in this technical review note are the result of careful screening of many hydraulic and hydrologic models. methodologies, hydrological and hydraulic modeling software programs and design procedures available today to the drainage engineer.