There is considerable discussion regarding the appropriate definition of road categories. This should of course be based on local conditions and priorities relating to transport policy, strategy, responsibilities, traffic characteristics, economic and social factors, and not least the financing available.
For the consideration of knowledge presented and disseminated on the gTKP website it is necessary to provide at least a broad guidance on road categorisation terms. This 'benchmark' can then be used to adapt terminology to meet local requirements.
In a national network, roads are often categorised with terms such as Primary, Secondary, Tertiary and Access. Much of the knowledge presented through the gTKP Rural Transport web pages relates to Tertiary and Access Roads. These are the roads that present particular technical and management challenges, however their existence and condition can significantly encourage or hamper local social and economic development, and hence influence the impact of poverty alleviation initiatives. We can further identify these road categories as follows.
The US Federal Highways Administration (FHWA) defines Low Volume Rural Roads (LVRR) as carrying less than Annual Average Daily Traffic (AADT) 400, i.e. 400 motor vehicles per day. This is broadly the traffic level that could be considered to be Tertiary for a wide range of countries.
Lebo and Schelling (World Bank 2001) discuss Rural Transport infrastructure for Basic Access or Very Low Volume Rural Roads (VLVRR) relating to routes carrying less than 50 motorized four-wheel vehicles per day (VPD) equivalent.
In developing countries and transitional economies, both of these rural road categories relate to routes that are likely to be carrying substantial flows of intermediate means of transport such as bicycles and animal drawn carts, as well as motorcycles and locally made/adapted vehicles. However using appropriate equivalence factors for the various vehicle types will enable VPD/AADTs to be calculated for local conditions.
The maintenance of Tertiary Roads is typically the responsibility of local authorities (with or without the assistance of central government), whereas the maintenance of Basic Access roads, by intention or default, often lies principally with communities, groups or individuals (again with or without external assistance).
These categorisation guidelines are not definitive and serve purely to place in context the knowledge disseminated through this website. As stated above, the local categorisation of roads and the application of knowledge and good practice should be based on consideration of local conditions and factors, and adapted to local needs.
It is unfortunate that although these two categories of rural road are by far the most extensive in network length, they invariably receive the least financial (in many cases no) provision per km. Furthermore, adverse climatic and physical factors, and scarce technical and management skills usually mean that the development and maintenance of these routes present a great challenge for communities, technical personnel and other stakeholders.
On the positive side, these lower category routes do not necessarily require high technology approaches and offer possibilities for traditional or ingenious techniques incorporating local resource use to provide appropriate, low-cost and sustainable transport solutions.
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Updated March 2010