Effect of Working Conditions on Forwarder Productivity in Cut-to-length Timber Harvesting on Sensitive Forest Sites in Ireland

Time and motion studies were conducted to evaluate the impact of terrain characteristics and work methods on forwarder productivity in cut-to-length timber harvesting system. Time elements of the forwarder operation that were recorded included: loading time, unloading time, and travel times for the loaded and empty forwarders. Productivity was evaluated as the volume of the timber payload during the corresponding productive system time (PST) in m ³h[PST]^-1 without delays. It was found that the forwarder productivity reduced exponentially with increasing distance of timber extraction, and independently of the payload. The productivity for forwarding operation on clearfelled sites classified as easy and difficult terrain conditions, ranged from 24.13 to 27.65, and 15.90 to 27.46 m³h[PST] ^-1, respectively. The corresponding rates of decline in productivity ranged from 0.0494 to 0.0082 m³h[PST]^-1 and 0.163 to 0.0116m³h[PST]^-1 per metre of extraction distance at 50 and 300 m, respectively. These observations suggest that maximisation of payload and optimisation of timber extraction distance are more crucial for economic forwarding on difficult sites. Uphill extraction reduced the forwarder productivity by between 0.8 and 5.1 m³h[PST]^-1 compared to downhill, hence, the latter should be adopted wherever it is practicable, for economic reasons.