Even long logs can be transported efficiently out of mountainous sites

Longer log forwarding productivity between different load capacity forwarders

Hidenori Suzuki (a), Satoshi Yamaguchi (a), Hiroko Muneoka (a), Tatsuya Sasaki (a), Yoshiaki Tanaka (a), Yuta Inomata (a), Takayuki Ito (a), Masahiro Moduna (a), Seishiro Taki (a), Takumi Uemura (a), Kengo Usui (a), Chikashi Yoshida (a), Hirokazu Yamaguchi (a), Masahiko Nakazawa (a), Masaki Jinkawa (b), Kotaro Zushi (c)

(a) Department of Forest Engineering, FFPRI, Tsukuba, Ibaraki, Japan.

(b) Kyushu Research Center, FFPRI, Kumamoto, Japan.

(c) ToyamaPrefectural Agricultural, Forestry & Fisheries Research Center, Tateyama, Toyama, Japan.

Bulletin of the Forestry and Forest Products Research Institute 19(1) (No.453), 69-77, March 2020, FFPRI
URL: https://www.ffpri.affrc.go.jp/pubs/bulletin/453/453toc-en.html

Many if not most of the logs that are processed at sawmills in Japan are less than 4 meters long. In the future, if longer logs are brought in, it will be possible to develop new applications such as cross members (beams, girders, etc., that are used horizontally) for large-scale wooden buildings and houses. Transport at felling sites is often done using hauling machines called forwarders; however, such machines have been impractical for longer logs due to the length and shape of their beds.

Therefore, we conducted a study on the efficiency of a widely used medium-sized forwarder (carrying capacity 4t) and a large forwarder (carrying capacity 6t) for hauling longer logs. Hauling efficiency is the mass that is carried per unit time (m³/hour). As a result, we found that as log length increased, hauling efficiency decreased, regardless of the type of forwarder. However, because the rate of decrease was lower with the large forwarder, we could see that the large forwarder was more suitable for hauling longer logs. If large forwarders are used, even 8m logs can be transported with the same efficiency as conventional medium-sized forwarders that carry 4m logs.

This result indicates that it may be possible to transport longer logs efficiently, which would help to create new value for lumber.

Photo: Transporting 8m logs with a medium-sized forwarder (left) and a large-sized forwarder (right).
When logs are longer than the bed length, as with medium-sized forwarders, they are loaded by leaning them up and past the front of the bed. However, because such forwarders can only be loaded with logs that are less than the maximum load capacity, their hauling efficiency is not very good.