Gravel roads are the type of roads that are built with granular materials, are not built with bituminous or concrete materials.
This roads are mostly found in most of villages in Tanzania In some regions like Kigoma, Shinyanga,Iringa and Tabora.
These roads sometimes fails without reaching their design life. There are several reasons that make these roads fail without being used as expected in design process.
These reasons are as follows,
1. Climatic conditions.
Most parts of Africa including Tanzania faces rainfall for some months, the rain fallen tends to weaken the sugrade of such roads Therefore once some vehicles pass through such roads creates some holes on the roads that are directly reflecys te wekeness of subgrade.
2. Poor construction methods apllied.
This is the among of common problem causing the failure of gravel roads. Most of roads are built with some common Technology, are built basing on experience of Engineer. Therefore an engineer can sometimes apply a technique which may not suite in such areas for example in Template regions for example Mufindi district faces much this problems. Consider an image below,
3. Rapid growth of plants near the roads.
The growth of plants near the roads tends to create accumulation of moisture on rodas surface therefore weaken the top layers of the road, once an vehicle pass through the road ma cause potholes on top layer of roads.
4. Poor design of such gravel roads.
Sometimes these roads because of poor design processes, for example failure to recognize the number of road user, failure to select a suitable thikness of layer on such gravel roads, and failure to select the suitable materials for road to be built. Consider the image below,
5. Luck of proper maintenance program.
For example in most of authorities
