WHO'S WHO IN ROADS
Prioritising gravel to paved routes in KwaZulu-Natal A high percentage of South Africa’s road network is unpaved, which, given budget constraints, poses a challenge in terms of their upkeep. This is compounded by a shortage of suitable gravel sources. A more viable option would be to pave highertrafficked sections. The following KwaZulu-Natal Provincial Road Network case study supports that argument. By Gugu Ndlovu and Professor Dhiren Allopi*
T
he regravelling of unpaved roads at their optimal frequency extends the life of gravel borrow pits and also results in significant savings on road infrastructure budgets. Achieving this requires an in-depth understanding of gravel material behaviour when deployed as the wearing course under prevailing conditions. This must also be supported by an effective decisionsupport system for the prioritisation of the maintenance and upgrading of unpaved roads. Within KwaZulu-Natal, the province’s Department of Transport is responsible for more than 24 713 km of gravel roads within the provincial road network. This requires adequate annual funding to cater for new access roads, and the maintainance and upgrading of the existing unpaved network. There is a vital need to enhance the existing planning criteria, and thus the optimal utilisation of funds.
Background To date, the department has made significant progress in capturing all declared public roads into a single geographic information system (GIS). Both the declared paved and unpaved provincial road networks have been classified in accordance with the Technical Recommendations for Highways (TRH26, 2012). Traffic count surveys and road network condition visual assessments, in line with the Technical Methods for Highways (Draft TMH22, 2013), have also been carried out. The latter assessments were completed following a call made by the National Department of Transport for all provinces to have updated input data for use in the Rural Road Asset Management System (RRAMS). This has a direct bearing on the allocation of the Provincial Road Maintenance Grant (PRMG) for the maintenance of the unpaved road network. Among other reasons, the PRMG was also established to supplement
Gravel-loss survey This is an edited version of a technical paper. The full paper and references are available from the authors. Email: gugwana84@gmail.com / allopid@dut.ac.za.
provincial investments for routine, periodic and special maintenance (Department of Transport Conditional Grant Framework 2016). The outcome of KwaZul-Natal’s assessments shows that the network condition has worsened compared to previous years. Many issues have contributed to this, such as the underfunding of road maintenance projects, shortage of suitable road material sources, as well as the lengthy process of obtaining environmental approvals for borrow pits. The majority of the funds to date have been used for the provision of new gravel roads and for the upgrading of gravel roads to paved roads.
Prioritisation methodology
The developed prioritisation system for the upgrading of unpaved to paved roads in KwaZulu-Natal ranks gravel road segments using selected prioritisation factors. The baseline traffic criteria used is 200 vehicles per day (vpd). Each prioritisation factor is represented as a separate GIS shape file layer. The factors were carefully selected to ensure that the department’s project priorities align with national and provincial strategies. Much of the data comes directly from the Provincial Growth and Development Programme, as well as outputs from other national and provincial strategies (Department of Transport Project Planning These figures show the road visual assessment information that can be stored within the Gravel Road Management System (GRMS) Framework 2018).
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IMIESA April 2021
