Cataldo Maria Francesca, MSc

Forwarding technology is well established in use around the world but, at the same time, forwarders are expensive machines that require a good planning to ensure the sustainability of operations. In addition, forwarder market is characterized by a limited pool of customers, therefore innovation attempts may be limited compared to other product development industries. Since the steps towards a full automation of operations are still at their beginning, improvements of forwarder machines may rest in developing and integrating components that could contribute to an increased effectiveness. To respond to such challenges, the Forwarder2020 project developed innovative components that were integrated in a number of forwarder prototypes based on a market pull approach that resulted in a flexible adaptation to customer requirements and work environments. Since one of the typical work environments was that of low access forests, some components (i.e. suspended cabin and transmission system) were engineered to enable faster and safer operations and to economize fuel. As a common validation step is that of bringing field evidence on the performance improvement, this study evaluated the operational speed, productivity and fuel consumption of a forwarder prototype in conditions of a steep-terrain low-access forest. The main findings were very promising as the prototype was able to operate at significantly increased speeds and the fuel savings were evident. For an average forwarding distance of about 1.5 km, net productivity and efficiency rates were estimated at 14.4 m3/h and 0.07 h/m3, respectively. They were related to the availability of wood, and further improvement of such figures is possible by a better organization of tree felling and processing. Operational speed was affected by the condition of skid roads used for forwarding, which were harsh. During the transportation tasks developed on roads typical for forwarding, the machine was able to sustain average speeds estimated at 8 km/h. As a matter of fact, in such tasks, the dominant operational speed (almost in 100% of the cases) was higher than 5 km/h irrespective of the road condition. Hourly fuel consumption was estimated based on the time in which the engine was working and it amounted to 17.1 l/h. More importantly, by considering the forwarded payload in terms of volume and mass, the unit fuel consumption was estimated to be 1.25 l/m3 and 1.47 l/t, respectively. These results bring evidence on the performance improvement by modular innovation. In fact, such solutions could answer the challenges related to the sustainability of forest operations in low access forests.

Forwarders often load logs organized in large piles by modified farm tractors, skidders, animals, other forwarders, etc., but currently, there are no studies on how the different concentrations of logs affect forwarder performance in terms of time consumption, productivity, and costs in forwarding operations. A study was conducted in three locations situated in Bulgaria (sites A and B) and in southern Italy (site C): in site A the logs were spread in the stand, in site B they were concentrated in large piles at the roadside, whereas in site C the logs were organized at the roadside in piles of medium size. The average forwarder productivity in site A obtained at an average forwarding distance of 1780 m, an average payload volume of 9.83 m3, and an average number of grips of logs with the crane grapple, during loading (22.97) and during unloading (8.97) per cycle, is 10.43 m3·PMH-1 (PMH, productive machine hour) and 9.93 m3·SMH-1 (SMH, scheduled machine hour), respectively. In site B the productivity rate was lower than that registered by the forwarder operated in site A: 9.38 m3·PMH-1 and 8.81 m3·SMH-1, respectively, at an average forwarding distance of 3760 m, average payload volume of 15.04 m3, and a mean number of grips of logs with the crane grapple, during loading and during unloading, of 23.57 and 14.10 per cycle, respectively. With regard to site C, the average machine productivitiy was 12.39 m3·PMH-1 and 11.85 m3·SMH-1, travelling a mean forwarding distance of 1630 m, transporting a mean load volume of 13.63 m3, and performing an average number of grips of logs with the crane grapple, during loading of 26.52 and during unloading of 12.36 per cycle. The ratio between the number of grips of logs with the crane grapple during loading and unloading operations in site A is on average 2.56, but in site B it is significantly smaller – mean of 1.67, due to the larger number of logs in the grapple when loading from large piles. Site C shows a loading and unloading number of grips ratio intermediate between the two Bulgarian sites. This ratio is characterized by the concentration of logs in the stand. Concentration in larger piles results in a larger volume of grappled logs by crane, and hence, lower time for loading of the forwarder and higher productivity. The obtained results show that the dispersion of small piles of logs results in a smaller volume grappled, a greater number of crane cycles and a larger loading distance, which generally, increases loading time. The larger volume of logs in the crane grapple and the shorter loading distance, when the loading operation is carried out from larger piles at the roadside, lead to less loading time. Gross costs for forwarders were 65.14 € PMH-1 at Site A, 72.96 €·PMH-1 at Site B, and 85.58 €·PMH-1 at Site C. When the forwarders were productive, the costs were 6.35 €·m-3 in site A, 7.90 €·m-3 in site B, and 6.90 €·m-3 in site C.