Local Road Management Manual 72 4.1.1 Surface distress on unpaved local roads The condition ratings for local roads that are recommended in the preceding section are based on the degree of distress or defects over the gravel pavement of the subject local road. These distresses occur due to the interplay of the quality of road materials, traffic volume, local weather conditions and construction methodology. The degree of distress impacts on the ability of the gravel road to provide access to vehicular traffic. These distresses are normally identified visually as they are evident on the gravel surface. Structural defects on the pavement are harder to ascertain and may require further testing of the sub-grade below the pavement. Table 3.4 illustrates the typical distresses observed on Local Roads, as defined by the Unsealed Roads Manual: Guidelines to Good Practice developed by the Australian Road Research Board (ARRB) Group. Table 3.4 Typical Gravel Pavement Distresses Pavement Definition Sample Visual Identifier Distress Corrugations These are material displacements transverse to the carriageway forming parallel ridges. These may be caused by the dynamic impact of the traffic volume unto base material of insufficient quality. These may be repaired by improving the road alignment; better compaction; use of better binding surface materials; or paving of high stress areas.