virtually all of new zealand's highway pavements usually consistof one or more coats of a sprayed seal over unbound granular layers. The standard new zealand design and construction techniques are being applied to heavy-duty forestry roads. In a recent case study, a private forestry arterial road carrying heavily loaded logging trucks was examined. The advantages and limitations of new zealand's approach to seal coat design with respect to the forestry roads are discussed. Bitumen application rates calculated from national highway design algorithms resulted in flushing in the arterial forestry roads because the surface treatment contains excess bitumen for the axle loads. Experimental work that has been instigated to further the development of seal coat design, construction techniques, and specialized equipment suited to the special requirements of forestry roads sustaining heavy loads is discussed. The concept of cover aggregate embedment and surface hardness is also considered. This paper appears in transportation research record no. 1291, Fifth international conference on low-volume roads, may 19-23, 1991, raleigh, north carolina, volume 2.
Abstract