Harvest and transport account for 70% of the total roundwood production costs in South Africa. A full costing of the existing and modified transport system was completed and significant cost savings were demonstrated, excluding the cost of upgrading the roads. These were used to determine the economic feasibility of the upgrades and to evaluate the suitability of the model.
Ferrer, Agricultural Economics Department, University of KwaZulu-Natal, for advice and assistance with the economic aspects of the project. Zaverdinos, School of Mathematics, Statistics and Information Technology, University of Kwazulu-Natal, for his mathematical assistance with the derivation of the model.
INTRODUCTION
In South Africa, primary and secondary transport together can account for up to 55% of the mill-delivered cost of pulpwood (Morkel, 2000). Transport costs in forestry are composite costs, which consist of road use costs (vehicle operating costs), road construction costs and road maintenance costs. Objective one: To assess timber extraction in forest harvesting systems to understand the equipment and methods used and the impact it has on the South African forestry industry.
This will be done to minimize the overall cost by making optimal use of the available transport systems. Objective four: Apply the model to two case studies to test the functionality and economic viability of the model.
A REVIEW OF TIMBER EXTRACTION IN FOREST HARVESTING SYSTEMS
- Aerial
- Cable
- Intermediate technology (motor-manual)
- Highly mechanised technology
- Cable skidders
- Grapple skidders
- Forwarding
- Articulated forwarders
- Tractor and trailer as a forwarder
- Conclusion
Landings require a larger area than that of the cut-to-length method due to the bucking and debarking carried out on the landing (Pulkki, 2002). This can be attributed to the increase in labor costs, but also to the decrease in labor availability due to the advent of the AIDS pandemic. The soil-based harvesting systems described in section 2.2.3 provide an overview of how the equipment described in this section contributes to the harvesting system as a whole.
Slogans can also smother trees before the skidder returns, reducing delay times (de Wet, 2000). In general, the smaller the timber being harvested, the greater the need to bundle the timber into bunches corresponding to the size of the grab (Ackerman, 1998). The tractor-trailer combinations (see Figure 2.12) are relatively low-capital alternatives to the purpose-built freight forwarders for bulk lumber transportation (Wilhoit and Rummer, 1999).
Forwarding with combinations of conveyors and tractor trailers contributes the largest proportion of timber harvested in South Africa, as it is most suitable for the cut-to-length method, which is a well-established practice.
A REVIEW OF FOREST ROADS IN SOUTH AFRICA
- Forest Road Classification and Standards
- Conclusion
The subgrade plays a critical role in the drainage and performance of the final road surface (ODF, 2000). A and B axis roads, the subgrade must be shaped (crowned, beveled or sloped) to the correct dimensions and compacted to the correct moisture content prior to the application of the wear layer. On roads that will be used during wet weather, a wear layer also improves traction and improves the road's resistance to erosion.
This can be primarily attributed to the lack of awareness of the importance of maintaining forest roads and the financial implications for transport operations and forest management (Ackerman and Strydom, 2000). The purpose of forest road maintenance is to maintain the road and structures to the original intended design standard. For safety reasons and fire protection, bushes should be cleared and grass cut adjacent to the road.
Drainage can be considered as one of the most important elements for the design and successful service of forest roads. During dry weather, the smoothness of the road should be maintained by removing wrinkles and scratches by blading. If excessive defects appear on the road surface, such as abrasion or structural failure of the coating flow, either from lack of maintenance or extreme weather conditions, then rework and compaction may need to be performed.
Surface material gradually breaks down or is lost to the side of the road after prolonged time. Once the stage is reached where the road standard can no longer be maintained due to the loss of material, surfacing material must be added to restore the original design standard of the road (ODF, 2000). The main factors affecting the safe serviceability of a road depend mainly on the characteristics of the design vehicle.
THE DEVELOPMENT OF AN OPTIMUM ROAD UPGRADING MODEL
- Model Description
- Derivation of a Single Compartment Model with no Double Handling
- Derivation of a Single Compartment Model with Double Handling
- Derivation of a Multiple Compartment Model with no Double Handling
- Derivation of a Multiple Compartment Model with Double Handling
- Model Demonstration
Second, the distance to which the road needs to be improved, either at the edge of the divide, remains at the existing depot or at a point between the two. At this stage it is assumed that the same vehicle moves the timber from the log across the edge of the compartment to the existing storage in Figure 4.2. Second, the cost of moving timber by STT from the end of the improved road to the existing A or B-elass road.
Schematic of the road upgrade and transport problem for a single compartment, where tdis is the total distance from the edge of the compartment to the existing depot. Distance of EPT from the edge of the space to the end of the upgraded road (km). There is therefore no optimal point somewhere between the existing depot and the edge of the room.
During cable and slip work it is often not possible to slide wood along the edge of the compartment. A vehicle moves the timber from the stump along the edge of the compartment to the improved road (EPT) and the costs of moving timber within the compartment were excluded. The decision to upgrade depends only on the compartments in front of the existing improved road.
Therefore, equation 4.3 still applies to the multicompartment model and is expressed in terms of the threshold quantity (TTin t, equation 4.11). If upgrading the road to the next compartment reduces the number of tonnes of timber before the proposed road upgrade to a value lower than the threshold tonnage(77), then the road may not be further upgraded. Threshold tonnage for the next compartment before the improved road (t) Distance from the end of the improved road to the next compartment (km).
III 0
MODEL APPLICATION IN TWO CASE STUDIES
- Machine and road upgrading costs
- Influence of road upgrades on travel distances and cost saving
- Conclusion
First objective: To demonstrate the application of the model by recommending certain road improvements in the study areas. The layout of the existing configuration was identified in terms of roads, warehouses and the distribution of timber delivered to the various warehouses (c! Figure 5.1 and Figure 5.2). To determine whether implementing the road improvements in Table 5.6 will create a more cost-effective transportation system, a cost comparison should be made between the existing and the modified configuration.
STT costs from the sink to the processing plant are excluded, since all the wood is transported along the same route with the same vehicle, regardless of the road upgrade. In Table 5.1 0, a large number of compartments are cut in the first year and represent 61% of the returned investment. On further investigation after the second rotation, only 75% of the road upgrade investment was recovered.
The upgrade to Depot C was fundamentally incorrect, but was included in this discussion to point out possible shortcomings of the model. The three capital budgets demonstrated in this section reaffirm the suitability of the model developed in Chapter 3. The road improvements used to demonstrate the application of the optimal road improvement model used location and time specific input.
These data were related to the specific study area in terms of the harvesting system used, the costs of renewing machinery and roads. Figure 5.7 Sensitivity of border tonnage to road improvement cost and change in extended primary transport rate (Rept) and secondary terminal transport rate (Rstt) for the model described in equation 4.11. While a detailed economic analysis, including a cost savings calculation and a capital budgeting system was used to verify the road improvements and applicability of the model in a real-world scenario.
The model was shown to perform well under appropriate assumptions and with a simple analysis of the study area. A limitation of the model is that for the road upgrade to be viable, the road accessing the threshold area must be placed on the general route along which the timber would have flowed in the existing configuration.
CONCLUSIONS AND RECOMMENDATIONS
Two of the three upgrades returned the capital invested in the road upgrade after one rotation (14 years). Therefore, in the second round, provided that the road is maintained to the original design standard, a significant cost saving will be made in the transport system. In the derivation of the optimal road upgrade model, it was determined that the threshold tonnage is the minimum required tonnage to be transported over a particular road to warrant the upgrade costs.
The model did not perform well due to certain terrain constraints which limited the location of the road upgrade. This showed the limitation that the model cannot be used to consider alternative extraction routes. A sensitivity analysis performed on the model illustrated that the smaller the difference between the primary and secondary transport rates, the more sensitive the model becomes to the upgrade costs.
Therefore, if the difference between the transport costs is less than about R4fI.km-I, the upgrade costs must be carefully calculated. For one of the successful upgrades. Given the current economic situation in South Africa, it is likely that the tax rate will decrease rather than increase in the coming years. While curbside loading is limited by terrain in many cases, it is more often than not done because of the primary and secondary phases of transportation performed by different companies.
The model does not help in planning new roads, but focused on the decision to improve existing roads. It is assumed that the network is already optimal in terms of alignment and only needs improvement in the standard of certain routes to allow the secondary terminal. With these different rates, the model would have to be run iteratively until the optimal transport system is reached.
Proceedings of the International Conference on Timber Harvesting and Transport Technologies for Forestry in the New Millennium. USDA Forest Service, New Orleans, Louisiana, USA www.pfmt.org/glossary/publication/default.htm Accessed November 21, 2002.
APPENDICES
KmI IShift l~avall 85% avad Rlton Rltlkm MinIIo8d Rlton AMun Man Rltlkm Man Rltlkm Rltonlkm R lTonne I.
