ROADS & BRIDGES
The causes and consequences of edge breaks Edge breaks are not just a local phenomenon. They are internationally highlighted as a major contributor to road accidents and fatalities. This is Part 1 of 2 in a series highlighting the problems and offering solutions and recommendations. By Johan Muller*
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lassified alongside potholes under the general ‘pothole pandemic’, edge breaks basically fall under the same mode of road surface deterioration. However, in addition to ageing and deformation in the wheel tracks, they are actually more dangerous and costly to repair properly. Edge breaks generally occur when the road shoulder is worn. Professor Louis de Villiers Roodt, PrEng, published an excellent article, entitled ‘Road
Road crossfall and washing away of gravel with additional support of some grass in places contributed to the edge breaks
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IMIESA September 2021
Safety, Maintenance and Claims for Damages, Lessons from cases and investigations’, which formed part of the proceedings of the 33rd Southern African Transport Conference (SATC 2014). Roodt stated that claims against roads authorities have escalated since the capping of Road Accident Fund payouts. Among the major factors related to accidents, damage and fatalities are typical road failures, which are mainly related to surface failures such as potholes and edge drops/breaks. Related to these road surface failures, the failure of services and maintenance in the road reserve
M6 Lynnwood Road edge breaks... shoulder gravel loss
also contributes to crashes. Lessons learnt from case studies indicate that road failures do not necessarily have to be in the normal wheel tracks to be dangerous, and maintenance interventions of the full width of the trafficked lanes are essential. A few of the causes of edge breaks and edge drops are detailed as follows: • Burst water pipes and sewerage systems in major and minor metropolitan municipalities often result in a sag curve, which is caused by aged water pipe and sewer reticulation systems. As an example, earlier this year the residents of Emfuleni Municipality had weeks of interrupted water supply due to burst pipes – and the same holds true for most formal and informal human settlements. Municipalities have not prioritised the replacement of these pipes for many decades. Water and even raw sewage dam and run over the road surfaces into the kerb inlets or wash away the support material next to the road surface. • Rainfall and stormwater run-off on to the roadside support structure and road reserve areas causes mass volumes of gravel and soil material to wash into drainage systems and water catchments in the absence of kerbs and stormwater reticulation. The
