System Balance In Multi-Stage Timber Transportation: A Case Of Mkumbara Skyline, Tanzania

Timber transportation is known to be the most important and expensive single component in timber harvesting. It is a crucial part in harvesting planning especially where difficulty terrain and long distances are involved. This paper presents a study of a skyline logging system, Mkumbara, Northeast Tanzania, where difficult terrain and distances cause concern for system balance in a multistage transport system. The stages were forest to upper landing by trucks and tractor, upper to lower landing by skyline, and eventually lower landing to the mill by other log hauling units. This study identified the situation and workplace factors influencing productivity and costs; assessed the coordination of the different harvesting activities, and determined the presence of “system balancing” required for efficiency. The study involved assessment of productivity and costs of timber harvesting for the skyline system from gross and detailed work-studies. The operations assessed include: timber cutting, log transport to the skyline upper landing, terminal operations, skyline operation, and log hauling to the processing mills. The study revealed that although the potential of the skyline stage was not achieved, log hauling by tractors from the forest to the upper landing was the major bottleneck. Log transportation from the lower landing to the mill need to be improved. The mill demanded 60m3 of logs per day while log hauling to the upper landing was 38.8m3 per day. Unit cost at the mill amounted to Tanzania Shillings 6,550/-, with the hauling from forest to the upper landing being the highest, contributing 30% of the unit cost. The daily productivity and costs were imbalanced between all subsequent stages, however, it is recommended that improvement of the forest to upper landing stage could greatly increase productivity, and decrease unit cost, even without large capital investment. TJFNC Vol. 75 2004: pp. 91-9