A review of some recent geometric road standards and their application to developing countries

Since 1980, Australia, Britain and the United States have all made major modifications to their recommendations for geometric design standards for rural roads. This report reviews the research that formed the basis of the current standards under the headings of design speed, sight distance, horizontal and vertical alignment, and cross-section. Standards that have traditionally been applied in developing countries are also discussed. It is noted that traffic requirements, road safety and network considerations are different in developing countries and that, in order to develop local standards, it is convenient to define the objectives of road projects in terms of three levels of development of the road network. These are: Level 1: to provide access; Level 2: to provide additional capacity; Level 3: to increase operational efficiency. It is only when the objectives of the road are at Level 3 that standards such as those developed in Australia, Britain and the United States are relevant and the principal assumptions in these standards are reviewed to assist in their adaptation to roads in developing countries. For the abstract of the second part of this report see IRRD 815403.