We evaluated strength at the road surface and bank using soil compaction tests and penetration tests at 24 points on six roads in Kami-City. Two types of spur roads, such as those designed for trucks or forwarders, were observed in this study. The earth works construction methods were divided into two types: (1) cutting and banking at the same location and (2) surface soil removal by wide cutting, followed by re-banking for construction of the road body. Through evaluation of soil compaction and penetration tests, we found that most spur roads exhibit less road body strength than public roads do. The ratio of compaction in spur roads was less than 85%, which is the value expected for public roads. Mixing removed soil with coarser soil and using the mixture for construction of the road body can be used to control the moisture content, as well as the maximum compaction characteristics, of road soil. Additionally, soil transportation in heavy vehicles during construction can enhance compaction. To improve spur road construction methods, better methods for on-site determination of soil type, moisture ratio, and soil compaction ratio without the need for laboratory tests are needed.

View full abstract

Drainage with rolling-grade seems cost-effective drainage method. However, its efficiency as a drainage method and water behavior on it remains unclear. In this study, we observed drainage along a spur road with rolling-grade to prove that the concaves of the rolling-grade function as drain spots. In addition, we also created a DEM of the road surface from stereo photographs to determine the impact of the concave shape on the efficiency and water behavior. The drainage quantity observed at the concaves far exceeded that outside the concaves, which indicates that the concaves function as drain spots. However, the drainage efficiency index, which is defined in this study reflecting the drainage ratio at the concave to rainfall, was low, particularly at the gradual and shallow concaves. It is possible that the actual extent of the area functioning as a drain spot exceeds our definition of "concave"; namely a 1-m long section including the lowest elevation part of the road. Conversely, the distribution of drainage within the 1-m long section was uneven, which implies that the drainage did not drain off from the whole extent of the section but threaded through the asperity of the road shoulder.

View full abstract

We focused on soil properties that appear to affect the strength of a surface and bed of a strip road. In addition, we clarified whether the properties of different soils caused differences in the strip road strength. The study area was a place covered by pyroclastic fall deposits in Numata City, Gunma. Two plots that were set in the same strip road were compared, and plot 1 was found to contain a lot more gravel but less clay and silt than plot 2. A difference in the Nd-values or dry densities was observed when a penetration test and a soil density test were performed. The difference in the values was attributed to the amount of gravel included in the soil. Further, a smaller difference in the compaction degree was observed between the two plots. This is because the operator increased the working hours for compaction in plot 2 so that the compaction degree in each plot was identical. In terms of bearing capacity using a simple instrument, plot 2 had a higher value than plot 1 in the cutting-side rut. The tendency observed in this case was opposite to that observed in other tests, but plot 1 had higher values in the fillingside rut, similar to the tendency observed in other test results. When the soil properties are unsuitable for compaction, it is important not to construct the road the strength of which is partly low by improving the poor soil properties through the use of soils suitable for compaction.

View full abstract

There is currently a focus on utilizing satellite yards as a means of reducing distribution costs in the Japanese roundwood supply chain. This study examined satellite-yard layout planning through roundwood procurement activities by a large-scale sawmill in Hyogo prefecture, and approximated the reduction effect of satellite yards on distribution costs. Satellite-yard layout plans were generated using a mathematical programming model, including a minimum of two satellite yards in each case. The reduction effects of satellite yards on distribution costs were 930.2 and 581.6 JPY/m^3, with fixed costs per satellite yard in the planning horizon (five years) of 5 million and 20 million JPY, respectively. The results confirmed the cost-reduction effect of satellite yards, and also suggested the importance of limiting their fixed costs to enhance the cost-reduction effect.

View full abstract

The collection of unused woody biomass resources left in forests such as logging residues has become the biggest issue in the biomass utilization business. To improve such collection status, it is necessary to consider how the enterprises, i.e. operators, make efforts. To clarify, a questionnaire survey was conducted on 461 companies, including forest cooperatives and raw material producers collecting actors and the covariance structure was analyzed based on the survey results. This analysis revealed that the key factor impacting on the collection status of enterprises was demand development. Not only did enterprises general management activities center on demand development, community-minded concepts also helped improve the collection status. In particular, regional partnerships play a key role.

View full abstract

The effect of intermediate support was analyzed in terms of reachability of mobile-yarder cable. Reachability shows the ability to set a cable from a point to another; judged on whether the cable comes into contact with the ground surface or not and averaging the ability results of each grid. The calculations of ability were performed by applying DEMs of the Chichibu in Saitama Prefecture, Kaneyama in Yamagata Prefecture, Thorl river basin in Austria, and Beartown state forest in Masatewsetts, United States. The maximum cable span was set to 300, 500, and 800 m respectively and the intermediate support increased reachability 1.5 to 3 times as compared to when it was not used.

View full abstract