ABSTRACT
12.01 The level of accessibility for particular transport aids making specific trips is influenced by a number of features of the actual infrastructure route selected for the trips. The features that impinge on accessibility are discussed under the headings of geometries, soils, climate and drainage. Each operational constraint to access is a physical barrier which denies access to specific transport means like walking, pack animals or motor vehicles. These constraints normally consist of one or more of four types. The first type is water-related or environmental constraints, which can completely deny access or limit access only during rainy periods, as described in Paras 9.17 to 9.19. The other three types of physical barriers - steep grades, sharp curves and inadequate width - either allow access all the time, except as modified by environmental constraints, or not at all.
