ACCESS to reliable road infrastructure remains a persistent constraint on economic development in rural South Africa, particularly in the Eastern Cape.
AVX Engineers has recently completed a study aimed at upgrading gravel access routes into durable surfaced roads that better connect communities to markets, schools, healthcare services and agricultural hubs.
According to Managing Director Camagu Xintolo, the geotechnical investigation and road design study adopted a holistic and data-intensive methodology.
It evaluated traffic volumes, pavement integrity, geometric alignment, drainage systems and environmental conditions, while also incorporating a community-based training and skills development programme to ensure local participation and long-term sustainability.
The project, supported by South African National Roads Agency, involved detailed assessments of multiple access routes to determine their suitability for upgrade. Field investigations included extensive test pits and Dynamic Cone Penetrometer (DCP) testing, enabling engineers to map subgrade strength, pavement layer thicknesses and underlying failure mechanisms in accordance with recognised standards such as TMH1 and TRH14.
“This data-driven approach ensured pavement designs were tailored to actual ground conditions, preventing under-design that leads to premature failure or over-design that inflates costs,” Xintolo said. He added that intrusive geotechnical investigations should be prioritised early in project planning, particularly where more than half of an existing road surface shows severe defects.
The study also highlighted the influence of local climate on infrastructure performance. The project area falls within a moist sub-humid climatic zone, with a Thornthwaite index between 0 and 20—conditions that significantly affect material selection. Xintolo noted that temperature sensitivity, especially in hot mix asphalt, must be carefully managed to avoid performance degradation under fluctuating weather conditions.
Drainage deficiencies emerged as a critical risk factor. Blocked culverts, overgrown vegetation, informal drainage channels and inadequate cross-fall were identified as major contributors to erosion and rutting. “Protection against these elements must be treated as a structural priority, as it directly influences the longevity of the road surface,” he said.
Recommended interventions include culvert rehabilitation and replacement, installation of stone-pitched drains and strict adherence to hydraulic velocity guidelines to safeguard both infrastructure and surrounding soils. The findings reinforce the importance of integrating drainage design with topographic and hydraulic considerations from the outset, particularly in climate-vulnerable regions.
From a design perspective, the study found that even at relatively low speeds of 40km/h, inconsistent horizontal and vertical alignments compromised safety and operational efficiency. Corrective measures included realignment of non-compliant curves, optimisation of cross-sections with properly designed side drains and chambers and the use of refined elevation profiles to guide upgrades.
Beyond engineering considerations, the project identified key risks early in the planning phase, including land acquisition requirements, environmental sensitivities, regulatory compliance and potential budget overruns. Mitigation strategies encompassed stakeholder engagement with landowners, environmental screening, occupational health and safety audits, and the establishment of a Project Liaison Committee to facilitate community involvement.
Xintolo emphasised that upgrading rural gravel roads delivers benefits that extend well beyond immediate infrastructure improvements. Durable surfaces reduce long-term maintenance costs thus freeing up public funds for further infrastructure investment, while improved geometry and drainage enhance road safety for all users, including pedestrians and non-motorised transport,” he said.
Improved connectivity is also expected to strengthen agricultural productivity, enhance market access and expand access to essential services—factors that collectively support sustained economic growth in historically underserved communities.
