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Optimization models and methods for harvest planning and forest road upgrading
Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The purpose of this thesis is to contribute to the development and the use of optimization models and methods to support efficient decision making in Swedish forestry. The main problem areas concerned are forest road upgrade planning and operational harvest planning. Today much of the planning is done manually by experienced managers. Forest management has a natural hierarchical structure based on the wide range of planning periods and organisational structure. The hierarchical harvest planning and the subdivision into strategic, tactical and operational levels are described from an Operations Research perspective. The description of the hierarchical structure differs between countries and there is a focus on the Swedish situation.

Road upgrading is becoming an increasingly important planning problem to secure a continuous supply of wood. In Sweden, during the periods of thawing and periods of heavy rain there is an uncertain accessibility to parts of the road network due to unfirm ground. The thesis addresses the optimization problem to minimize the combined road upgrade and transportation costs while meeting requirements on road standard such that accessibility to harvest areas is secured during all weather conditions. In this work mixed integer linear programming (MILP) models including multiple assortments, several time periods and a set of road classes are developed. For a typical forest district, the road upgrade problem becomes large and techniques to improve solution performance through model reformulations are discussed. The models are tested in a case study for a major Swedish company. For practical usage of the models we present the development of a new decision support system called RoadOpt. The development has involved the Forestry Research Institute of Sweden, two software companies and several participating forest companies. The system uses a GIS-based map user-interface to present and analyse data and results. The recently developed Swedish road database is an important part. The system is tested on a case study from Stora Enso.

The harvest planning problems addressed cover planning periods ranging from one year down to one month. Annual plans are required for budgeting, contracting harvest teams, contracting transportation firms and assuring road access. The main decisions deal with which areas to harvest, and by which team, during an annual period so that the industries receive the required volume of assortments. Overall decisions about transportation and storage are included. The monthly planning problem includes detailed scheduling of harvest crews, that is, the sequencing of areas for each team. The thesis addresses these planning problems and provides MILP models for each problem. Methods based on both a commercial solver and developed LP based heuristics are used. Models and methods are tested on case studies from Holmen Skog.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2005. , 6 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 956
National Category
Mathematics
Identifiers
URN: urn:nbn:se:liu:diva-28705Local ID: 13869ISBN: 91-85299-72-3 (print)OAI: oai:DiVA.org:liu-28705DiVA: diva2:249516
Public defence
2005-06-10, Glashuset, Hus B, Campus Valla, Linköpings Universitet, Linköping, 10:15 (English)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-12-10Bibliographically approved
List of papers
1. Operations research based hierarchical harvest planning in Sweden and elsewhere
Open this publication in new window or tab >>Operations research based hierarchical harvest planning in Sweden and elsewhere
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Harvest planning includes decision on different levels, both spatial and temporal,and is typically hierarchical in nature. Strategic forest planning includes decisions about nationwide forests and aims to maximize the sustainable production while preserving natural ecosystem processes and recreation areas on time horizons of one or several rotations, each representing 20-200 years. Tactical harvest planning decides which stands (or harvest areas) to be harvested over a several year rolling planning horizon under consideration of spatial aspects, e.g. road building and environmental concerns. On an operational level, annual plans are required for budgeting, contracting harvest teams and transportation companies and assuring road access. Moreover, managers decide weekly and monthly schedules for harvesting and transportation based on customer requirements. We provide an overview of hierarchical harvest planning and present the Swedish case. We also describe decision support systems, Operations Research (OR) models and methods more specific for the Swedish case, together with an international view of OR work within this problem area.

Keyword
forestry, hierarchical harvest planning, operations research, optimization, modelling, decision support system
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-86186 (URN)
Available from: 2012-12-10 Created: 2012-12-10 Last updated: 2012-12-10
2. RoadOpt: a decision support system for road upgrading in forestry
Open this publication in new window or tab >>RoadOpt: a decision support system for road upgrading in forestry
2006 (English)In: Scandinavian Journal of Forest Research, ISSN 0282-7581, Vol. 21, no S7. 7, 5-15 p.Article in journal (Refereed) Published
Abstract [en]

Road blocking due to thawing or heavy rains annually contributes to a considerable loss of profit in Swedish forestry. Companies have to build large stocks of sawlogs and pulplogs to secure a continuous supply during periods where the accessibility of the road network is uncertain. This storage leads to quality deterioration, which means loss in profit. One approach to reduce the losses due to blocked roads is to upgrade the road network to a standard that guarantees accessibility throughout the year. This article describes a decision support system called RoadOpt for the planning of forest road upgrading. The planning horizon is about one decade. The system uses a Geographical Information System (GIS)-based map user interface to present and analyse data and results. Two important modules are the Swedish road database, which provides detailed information about the road network, and an optimization module consisting of a mixed integer linear programming model. A case study from a major Swedish company is presented.

Keyword
Decision support system, Forestry, GIS, Mixed integer, Operations research, Road upgrading, Tactical planning, Wood flow
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-50303 (URN)10.1080/14004080500487102 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2012-12-10
3. Optimization models for forest road upgrade planning
Open this publication in new window or tab >>Optimization models for forest road upgrade planning
2007 (English)In: Journal of Mathematical Modelling and Algorithms, ISSN 1570-1166, E-ISSN 1572-9214, Vol. 6, no 1, 3-23 p.Article in journal (Refereed) Published
Abstract [en]

Road blocking due to thawing or heavy rains annually contribute to a considerable loss in Swedish forestry. Companies are forced to build up large stocks of raw material (saw and pulp logs) in order to secure a continuous supply when access to the road network is uncertain. Storage outdoors leads to quality deterioration and monetary losses. Other related costs due to road blocking are road damage and longer haulage distances. One approach to reduce the losses due to road blocks is to upgrade the road network to a standard that guarantees accessibility. We consider the road upgrade problem from the perspective of Swedish forest companies with a planning horizon of about one decade. The objective is to minimize the combined upgrade and transportation costs. We present two mixed integer programming models, which are uncapacitated fixed charge network flow problems including multiple assortments, several time periods and a set of road classes. One model is based on arc flows and one on route flows. For a typical planning instance, the models become large and we propose how to improve solution performance through model strengthening. The models are tested in a case study for a major Swedish forest company.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-86187 (URN)10.1007/s10852-006-9047-0 (DOI)
Available from: 2012-12-10 Created: 2012-12-10 Last updated: 2017-12-07
4. An optimization model for annual harvest planning
Open this publication in new window or tab >>An optimization model for annual harvest planning
2004 (English)In: Canadian Journal of Forest Research, ISSN 0045-5067, Vol. 34, no 8, 1747-1754 p.Article in journal (Refereed) Published
Abstract [en]

The problem we consider is annual harvesting planning from the perspective of Swedish forest companies. The main decisions deal with which areas to harvest during an annual period so that the wood-processing facilities receive the required amount of assortments. Each area has a specific size and composition of assortments, and the choice of harvesting areas affects the production level of different assortments. We need to decide which harvest team to use for each area, considering that each team has different skills, home base, and production capacities. Also, the weather and road conditions vary during the year. Some roads cannot be used during certain time periods and others should be avoided. The road maintenance cost varies during the year. Also, some areas cannot be harvested during certain periods. Overall decisions about transportation and storage are also included. In this paper, we develop a mixed integer programming model for the problem. There are binary variables associated with harvesting, allocation of teams, and road-opening decisions. The other decisions are represented by continuous variables. We solve this problem directly with CPLEX 8.1 within a practical solution time limit. Computational results from a major Swedish forest company are presented.

National Category
Mathematics
Identifiers
urn:nbn:se:liu:diva-22745 (URN)10.1139/X04-043 (DOI)2059 (Local ID)2059 (Archive number)2059 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2012-12-10
5. Short-term harvest planning including scheduling of harvest crews
Open this publication in new window or tab >>Short-term harvest planning including scheduling of harvest crews
2003 (English)In: International Transactions in Operational Research, ISSN 0969-6016, E-ISSN 1475-3995, Vol. 10, no 5, 413-431 p.Article in journal (Refereed) Published
Abstract [en]

The problem we consider is short-term harvesting planning for a total planning period of 4–6 weeks where we want to decide the harvest sequences or schedules for harvest crews. A schedule is an order or sequence of harvest areas assigned to each crew. The harvesting of areas is planned in order to meet industrial demand. The total cost includes harvesting, transportation, and storage. One considerable cost is due to the quality reduction of logs stored at harvest areas. There are a number of restrictions to be considered. Areas are of varying size and the composition of assortments in each area is different. Each harvest team has different skills, a different home base, and different production capacity. Another aspect is the road network. There is a cost related to road opening (restoring, snow removal). In this paper, we develop a mixed integer programming (MIP) model for the problem. The schedules are represented by 0/1 variables. With a limited number of schedules, the problem can be solved by a commercial MIP solver. We have also developed a heuristic solution approach that provides high-quality integer solutions within a distinct time limit to be used when more schedules are used. Computational results from a major Swedish forest company are presented.

National Category
Mathematics
Identifiers
urn:nbn:se:liu:diva-22331 (URN)10.1111/1475-3995.00419 (DOI)1532 (Local ID)1532 (Archive number)1532 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2012-12-10

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