関東森林研究69-1(2018)

論 文

Productivity of forwarding operation for long logs with side-loaded forwarder
横積式フォワーダによる長尺材集材作業の生産性
Chikashi YOSHIDA＊1, Tatsuya SASAKI＊1, Seishiro TAKI＊1, Masahiko NAKAZAWA＊1, Takumi UEMURA＊1
Hidenori SUZUKI＊1, Masaki JINKAWA＊1, Yasuo NAKASHIMA＊2, Noboru MOROOKA＊2, Koutaro ZUSHI＊3
吉田智佳史＊1・佐々木達也＊1・瀧誠志郎＊1・中澤昌彦＊1・上村巧＊1・鈴木秀典＊1・陣川雅樹＊1
中島泰生＊2・諸岡昇＊2・図子光太郎＊3*1 Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687
森林総合研究所*2 Morooka Co., Ltd., Ryugasaki, Ibaraki 301-0031
株式会社諸岡
*3 Toyama Prefecture Agriculture, Forestry and Fisheries Research Center, Tateyama, Toyama 930-1362
富山県農林水産総合技術センター
Abstract: For developing an efficient logging system for forest biomass, we generally consider the “Integrated Wood Logging
System” that conducts logging without separating butt logs from stem butts. Since integrated wood logs have a greater log lengthcompared to that of normal logs, there is a concern that the operating efficiency would drop if it was conducted using a generalforwarder with a rear-mounted loading platform. This is why a prototype forwarder with a side-loading platform was developed. In
this study, an on-site forwarding operation test was conducted to compare this side-loaded forwarder with a rear-loaded forwarderin the same class for evaluating the operating efficiency of the prototype. The results showed that the operating efficiency for loading
varied depending on the length of the logs used, and although no significant differences in load volume, loading speed, unloading
speed, and driving speed favoring the rear-loaded type were identified with 4-m logs, these values were higher for the side-loaded
type for 6-m logs. Although productivity with a forwarding distance of 200 m was 10% higher with the rear-loaded type for 4-mlogs, it was 46% higher with the side-loaded type for 6-m logs, calculated as 20.7 m3/h. These results suggest that a side-loaded
forwarder is more effective for loading long logs.
Key-words: side-loaded forwarder, productivity of forwarding operation, long log, integrated wood log
要旨：森林バイオマスの効率的な搬出方法を開発するため，端材を用材と切り離さずに搬出する一体材方式を検討している。一体材は用材に比べ材長が長いことから，荷台が後方にある従来のフォワーダへ積載する場合，作業効率の低下が懸念される。そこで，荷台が車体の側方にある横積式フォワーダを試作した。本研究は，試作した横積式フォワーダの作業性能を評価することを目的に，試作機と同クラスの後積式フォワーダとの比較による集材作業の現地試験を行い，積載量や作業時間等を分析するとともに生産性を算出した。その結果，積載する丸太の材長によって作業効率は異なり，積載量，荷積速度，荷降速度，走行速度のいずれも 4m 材では後積式の方が高いが有意差は認められず，6m 材では横積式の方が高くなった。集材距離 200m の生産性は，4m 材では後積式の方が 10%高いが，6m 材では横積式の方が 46%高く 20.7m3/h と試算された。長尺材集材における横積式フォワーダの有効性が示唆された。
キーワード：横積式フォワーダ，集材生産性，長尺材，一体材

there is a concern that loading them on a general forwarder withI Introduction
For developing an efficient logging system for forest biomass,a rear-mounted loading platform could decrease the loading

we generally consider the “Integrated Wood Logging System”

efficiency and the operation safety due to the restrictions on thethat performs logging without cutting off the stem butts and butt

length of the loading platform. Therefore, a prototype side-logs during the log bucking operations (3). Since the integrated

loaded forwarder with the loading platform positioned to thelogs are longer than the normal logs due to the stem butt length,side of the machine body was developed to load long length－67 －（受理日 2018 年 1 月 15 日）

logs (4). The prototype machine was designed to load long logs,

significant differences between the various elements.

and some of the characteristic features that differ from those of

4. Productivity Calculation Using the measured operation

existing side-loaded mini forwarders (working cars in forest)

time and the operation speed values, the cycle time forare as follows: maximum loading capacity, dumping functions

forwarding operation was calculated using equation (1), and theboth forward and to the side, and camera setup for handling

productivity was calculated using equation (2).

blind spots. Previous studies on the mini forwarders have

T = d (1 / v1 + 1/v2) + w (1 / v3 + 1 / v4) + t(1)

P = 3600 w / T(2)

included aspects on safety (1) and productivity (2). However,these studies have been intended for comparatively small

where T: cycle time (s), d: forwarding distance (m), w: loadedmodels for loading normal length logs, suggesting that thesevolume (m3), v1: driving speed loaded (m/s), v2: driving speed

studies have not clarified the adaptability of side-loaded

unloaded (m/s), v3: loading speed (m3/s), v4: unloading speed

forwarders for loading long length logs.

(m3/s), t: other times (s), and P: productivity (m3/h).

In this study, an on-site forwarding operation test wasconducted with the goal of evaluating the operating efficiency

III Results and Discussionof the prototype side-loaded forwarder, and the productivity

1. Work Elements Figure 1 shows the operation times for

was calculated for different log lengths and forwarder types

each work element carried out with the side-loaded type and thealong with an analysis of differences in loading volume,rear-loaded type. However, as there was a danger of load

operation time, and other factors.

collapse when using 2-m logs with the side-loaded type, andsafe driving was difficult for 8-m log loading with the rearloaded type, these testing were stopped. In the results, for theII Methods
1. Test Site The test was carried out in Himi City, Toyamaside-loaded type, seven cycles (three cycles for 4-m and 6-m

Prefecture, with a 54-year-old sugi (Cryptomeria japonica)

respectively, and one cycle for 8-m) were conducted, and for theplanted forest. The diameter at breast height (DBH) was 49.2 ±rear-loaded type, nine cycles (three cycles for 4-m, 6-m and 8-

9.2 cm (mean ± SD, same below), the tree height was 30.4 ± 4.4m, respectively) were conducted. The average cycle time for them, and the standing tree volume was 2.49 ± 0.92 m3. The spurrear-loaded type was 1,311 s, and that for the side-loaded typeroad used for the test had an average road width of 4.0 m, an

was 1,305 s. The average forwarding distance was about 200 m.

average longitudinal gradient of 7.0 degrees, and a maximum

Since the forwarding distance and the loading volume differedlongitudinal gradient of 14.5 degrees downhill. The loadingfor each cycle, simple comparisons were impossible. However,area was a distance of 165–255 m from the landing.

the times for each work element tended to be shorter for both

2. Machine Used The prototype side-loaded forwarder isdriving unloaded and driving loaded with the rear-loaded type.

based on MST-650VDL made by the M Company (loadingSimilarly, the times for both loading and unloading tended to beplatform capacity: 6.1 m3), which has been remodeled. Theshorter for the side-loaded type as well.

loading capacity is 5.3 m3, the maximum load volume is 4,000

2. Loading Volume Figure 2 shows the average loading

kg, and the maximum driving speed is 10 km/h. For thevolume for each log length for the rear-loaded type and the side-

performance test, the prototype side-loaded forwarder (below,loaded type. In addition, 8-m log operations were conductedside-loaded type) and MST-650VDL (below, rear-loaded type)

1400

were the two machines used.

1200

The test operations consisted of using a

1000

cycle time (sec)

3. Test Methodgrapple excavator to load the forwarders with logs on the spurroad and then forwarding them to the landing. There were fourtypes of logs loaded with log lengths of 2, 4, 6, and 8 m, and the800
600
400

tests of the forwarding operations with the side-loaded type and200

those with the rear-loaded type were tried three times each. The0rear-loaded typeprimary measurements were operation time of work elements,
driving unloaded

load volume, driving speed, and others. In addition, Tukey–loading

driving loaded

unloadingothersFig. 1. Cycle time of forwarding operations

Kramer’s multiple comparison test was used to determine the－side-loaded typeforwarder

68 －関東森林研究

100
loading/unloading speed (m 3 /h)

12load volume (m 3)

10b8
a669-1(2018)

aaa4
290

f80

fg

70eg

f60

bc

50

be40

bc

30

aac

20
10002m

4m6m2m8m6m8mlog length classlog length classrear-loaded type4m

Loading to rear-type
Unloading from rear-typeside-loaded type

Loading to side-type
Unloading from side-type

Fig. 2. Average loaded volume for each log length class

Fig. 3. Loading and unloading speed

Error bars represent standard deviation. Different letters indicate
significant differences. (Tukey–Kramer test, P < 0.05)

Error bars represent standard deviation. Different letters indicate
significant differences. (Tukey–Kramer test, P < 0.05)

two times with the side-loaded type, and one time with the rear-

led to the increased loading speed with the side-loaded type.

loaded type. Although the loading volume for 4-m logs wasHowever, the rear-loaded type required increased operation

higher with the rear-loaded type, no significant difference wastime due to the need to maintain balance during loading, whichfound (P > 0.05). However, for 6-m logs, the loading volume

could have probably caused the decrease in the loading speed.

was 23% higher with the side-loaded type, with a significant

In addition, these trends were observed for unloading speed asdifference (P < 0.05). In addition, although the loading volume

for the loading speed.

with the side-loaded type was significantly higher as the log

4. Driving Speed Figure 4 shows the driving speed for thelengths increased from 4 to 8 m (P < 0.05), with the rear-loaded

two machines with different log lengths. In addition, 8-m log

type, the loading volume was not significantly different for logs

operations were conducted two times with the side-loaded type,in the length range of 2–6 m (P > 0.05) and decreased

and those were stopped with the rear-loaded type. When theconsiderably for the 8-m logs. Compared with the side-loaded

driving speed for the two machines was compared, although notype with no walls at the front and back of the loading platform,

significant difference was found, the driving speed was fasterthe rear-loaded type with a barrier at the front had difficultywith the rear-loaded type for unloading and 4-m log loading

maintaining balance when loading long length logs, which

operations (P > 0.05). For 6-m log loading operation, the side-probably led to the decrease in the loading volume.

loaded type was 52% faster than the rear-loaded type (P < 0.05).

As mentioned above, the loading volume of the side-loaded

In addition, the driving speed tended to decline with increase intype was not significantly higher for normal use of 4-m logs

log length for the rear-loaded type; in particular, the speed withcompared to that with the rear-loaded type, and regarding the6possibility of loading approximately the same volume of thesevolume for long length logs of 6 m or more.
3. Loading Speed Figure 3 shows the loading speed andunloading speed of volume over time. Regarding the loading
speed of 4-m logs, no significant difference was observed

a5driving speed (km/h)

logs, the side-loaded type tended to achieve greater loading

between the side-loaded type and the rear-loaded type (P >abaabacac

4bc

32100.05); however, the side-loaded type was 1.6 times faster thanunloaded(uphill)

the rear-loaded type for logs of 6 m (P < 0.05). In addition, whenloading 8-m logs, although no significant difference was noted

2m4m6m8mlog length classrear-loaded typeside-loaded type

between the side-loaded type's speed for loading 6-m logs, theFig. 4. Average driving speed for each loading log length

rear-loaded type was slower than with 6-m logs. These results

Error bars represent standard deviation. Different letters indicate
significant differences. (Tukey–Kramer test, P < 0.05)

suggest that the volume per log increases with log length, which－69 －6-m logs was 32% slower than that with 4-m logs. On the otherloaded type, the difference was small. However, with longhand, there was no clear trend for the different log lengths withlength logs (6 m and above), the side-loaded type showed

the side-loaded type.

higher productivity. This result suggests that the side-loaded

Since the driving speed can be influenced by multiple factors

type could be effective for loading long length logs.

such as road shape, road surface, and loading volume, nosignificant difference was found for loaded log length on its

IV Conclusionown. However, compared with the rear-loaded type, driving

The results of the comparative analysis of forwarding

speed for the side-loaded type was less affected by changes inoperations using the prototype side-loaded forwarder and a rear-the log length. For this reason, the side-loaded type could beloaded forwarder of the same class did not show any significant

more effective for loading long length logs than the rear-loaded

differences between the two machines in terms of loading

type.

volume, loading speed, and driving speed for 4-m logs. For 6Using the analyzed operating time andm logs, the side-loaded type demonstrated higher operating

speed, the cycle times of the forwarders were calculated fromefficiencies. Based on the results of the calculated productivity,equation (1), and the productivities were calculated fromthe rear-loaded type’s productivity was higher for 4-m logs, but

equation (2). Figure 5 shows the productivities for eachthe side-loaded type’s productivity was higher when loading 6-forwarding distance. As we could not collect sufficient datam logs. This result suggests that for loading long length logs,

using 8-m log operations with the rear-loaded type and 2-m log

the side-loaded forwarder is a more efficient loading platform

operations with the side-loaded type, these entries were deleted.

configuration. However, the analysis described above is based

Productivity for the average forward distance of 200 m was as

on results from one test site; therefore, further data

follows. For the rear-loaded type, 2-m logs: 12.1 m3/h, 4-m logs:

accumulation and consideration will be required in the future.

17.8 m3/h, and 6-m logs: 14.1 m3/h. For the side-loaded type, 4-Acknowledgments: This work was supported by Cabinet

m logs: 16.0 m3/h, 6-m logs: 20.7 m3/h, and 8-m logs: 22.7 m3/h.

Office, Government of Japan, Cross-ministerial Strategic

Although the productivity for the rear-loaded type was higher

Innovation Promotion Program (SIP), “Technologies forwith 4-m logs than that with 6-m logs, the productivity for thecreating next-generation agriculture, forestry and fisheries”,

side-loaded type increased with an increase in log length. InSIP-Lignin Project (funding agency: Bio-oriented Technology

addition, when the productivity of the two machines for theResearch Advancement Institution, NARO).

5. Productivity

same log length was compared, we observed that although it
was 10% higher for 4-m logs with the rear-loaded type, it wasReferences

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