Road construction within a housing estate is necessary to provide standard access road and driveways into private dwellings. This type of road construction is on a small scale. The construction of these types of roads will be discussed under three aspects;
- Setting out
- Pavement construction.
Setting out means the establishment of center, width, existing level and formation level of the road. This activity is usually carried out after top soil removal. The layout can include straight lengths, turning bays and intersection curves. Drainage positions must be adequately set out as well.
Road center points, widths and levels can be set out using traditional methods with the aid of levelling instrument/ theodolite/ total station, ranging rods,levelling staff, measuring tapes, pegs, markers and so on.
After proper setting out has been done. Existing and formation levels, determined and marked out, earthworks can begin. Earthworks involve the movement of earth to and from sections of the road in such a way that the formation levels/ design levels of the road is achieved. This process is also carried out for the road’s drainage as well.
The earthworks prepare the subgrade. Once drainage and other buried services have been installed, pavement construction can commence. There are two types of pavements; flexible and rigid pavements.
Flexible pavements consist of materials that are applied in layers over the subgrade. Rigid pavement consist of concrete slab resting on to of a prepared subgrade the construction of flexible pavement should consists of the following layers.
A sub base layer of about 100mm thick on the subgrade. The sub base can consist of crushed stone or dry lean mix concrete followed by a surfacing layer of asphalt which can be around 60mm thick.