Productivity and costs modeling for tree harvesting operations using chainsaws in plantation forests, Tanzania
International Journal of Engineering & Technology
Timber harvesting in Tanzania still uses semi-mechanized and labour-intensive logging systems. Manual or semi-mechanised logging operations by using hand tools are more favoured due to cheap labour availability. These tools are operated by locally recruited crews characterized by low levels of skill and literacy. This study was designed to assess tree cutting crews using two man crosscut saws and develop productivity and production cost models in a learning by doing experiment. The experiments
... t. The experiments were designed in clear felling operations. Three experiments were set where each crew category was studied using time study and work sampling techniques that involved studying crews before training, after training and after the break at an interval of three months. Descriptive statistics and modelling was performed for each crews" performance. Specific crew"s productivity and cost models have been developed reflecting necessary and unnecessary delay times. The results showed that there is an increase in production rate of the crews after training with a subsequent fall in production rates as the crews resumed cutting after the break. Results showed that there was an average of 40% production increase after training and about 23% production fall after the break for all crew categories. Further the production costs were relatively lower after training as compared to other experiments in the study. Generally, the unit cost of operations observed in the three experiments was mostly affected by labour costs. This is because labour cost accounted about 94% of the hourly costs. This means that since crosscut saw used two people, then any increase in labour charges will linearly affect the unit cost of production at a significant level. This study has demonstrated the importance of training tree cutting productivity and production costs. On the job training of the crews is therefore recommended despite their experience for improved productivity at reduced costs.