The department of Transport has made an assessment on the condition of road network in South Africa based on the road condition data available from the various road authorities, which is summarised for paved roads in Table 1 and for gravel roads in Table 2 below.
Table 1: Summary of Paved Road Condition
Table 2: Summary of Un-Paved (Gravel) Road Condition
There are numerous factors influencing the performance of a pavement. The following five are considered the most influential:
- Traffic is the most important factor influencing pavement performance. The performance of pavements is mostly influenced by the loading magnitude, configuration and the number of load repetitions by heavy vehicles.
- Moisture can significantly weaken the support strength of natural gravel materials, especially the subgrade. Moisture can enter the pavement structure through cracks and holes in the surface, laterally through the subgrade, and from the underlying water table through capillary action. The result of moisture ingress is the lubrication of soil particles, loss of particle interlock and subsequent particle displacement resulting in pavement failure.
- Subgrade: The subgrade is the underlying soil that supports the applied wheel loads. If the subgrade is too weak to support the wheel loads, the pavement will flex excessively which ultimately causes the pavement to fail. If natural variations in the composition of the subgrade are not adequately addressed by the pavement design, significant differences in pavement performance will be experienced.
- Construction Quality: Failure to obtain proper compaction, improper moisture conditions during construction, quality of materials, and accurate layer thickness (after compaction) all directly affect the performance of a pavement. These conditions stress the need for skilled staff and the importance of good inspection and quality control procedures during construction.
- Maintenance: Pavement performance depends on what, when, and how maintenance is performed. No matter how well the pavement is built, it will deteriorate over time based upon the above-mentioned factors.
a) As an Honourable Member may be aware, it is difficult to eradicate potholes on the road network as the emergence of new potholes depends entirely on the extent and nature of rainfall in that month or year.
It is true that potholes cannot be eradicated, however, to ensure that roads are properly maintained, my department is providing support (supplementary funding of just over R12 billion per annum to provinces) through the Provincial Road Maintenance Grant that is ringfenced for the maintenance, rehabilitation, strengthening of paved roads, re-gravelling, gravel road blading and blacktop patching (including pothole repairs).
b) The value of maintenance backlogs to address the road condition was estimated to be R197 billion in 2013. Based on the assessment of the 2017 data and additional data being collected, this figure is expected to increase and the process to update this calculation is work in progress.