EPO: A Knowledge Based System for Wood Procurement Management

Enso-Gut&t is a Finnish company operating in pulp and paper industry. It has 1200 employees and its annual turnover is 700 million US Dollars. For its factories and sawmills it requires more. than 600 million cubic feet of timber as raw material annually, equalling to about 4CQNXl truckloads. Most of the timber is loaded from forests located all around Finland. About 85% of the logs are transported directly to the factories and sawmills by 250 trucks operated by Enso. Alternatively parts of the transportation are carried out by trains or waterways. The available timber is classified to several tens of categories, depending not only of the species of trees, but also of the quality and length of the logs. Every factory estimates its daily need in each category. Traditionally the dispatch centers have allocated one or more trucks for each foreman in the forests, depending on the amount of available timber, and the foremen have taken care of the control of trucks. Through increasing competition it became evident that this mode of operation had to be changed. Without more global guidance the trucks drove unloaded 50% of all their driving, and in worst cases two trucks loaded with the same type of timber passed each other on the road, driving into opposite directions. To guarantee the needs of the factories, rather large piles of logs were stored both in the forests and around factories. This storage period caused waste of money, and also the quality of the timber decreases when it is stored. Also a law was made recently in Finland stating that it is illegal to store timber in the woods more than a couple of weeks in summertime, because they provide an excellent reproduction environment for pests. On the other hand, when the factories have practically no buffer storage, quite exact schedules for arriving timber are mandatory. The existing, mainly manual system for wood procurement was far too inaccurate and slow to face the new challenges. Solution: the EPO system In the turn of the decade, Enso decided to develop EPO, a completely new system for its wood procurement, based on the highest available information technology. EPO is the Finnish acronym for Enso-Gutzeit’s Wood Procurement Management System. The EPO system as a whole covers all the operations of the wood procurement from strategic planning to actual deliveries to the factories and sawmills. The necessary data is collected on-line from the computing equipment of the forest foremen, forest harvesters and tractors, trucks, and plant receptions. In addition to data transmission through telecommunication cables, mobile data transmission is used where necessary. The foremen register the locations of forthcoming wood batches, consisting of piles of logs, on their electronic maps. The trucks can see their destinations on the electronic maps in their cabins, as well as the locations of themselves, determined by GPS satellite navigation (see Fig. 1). Tbe heart and the most challenging part of the system is EP02 software running in UNIX workstations of regional dispatch centers, each managing about 20 trucks. The main focus of this paper is in EP02 software, developed by VTT (Technical Research Centre of Finland) as a subcontractor of Carelcomp. Carelcomp is a Finnish software house specialized in information systems for forest industry. It has been responsible of the development of EPO as a whole. The purpose of the EP02 subsystem is to determine optimal weekly routes for the trucks, knowing the availability of timber and transportation vehicles, and the needs of the plants. The complexity of the problems solved in EP02 are caused by nutnerous reasons. There are lots of conflicting goals that should be optimized, and hundreds of different kinds of strict and desirable constraints are involved in the problem, some of which are very difficult to express in a mathematical format. To give an idea of the nature of the existing constraints, some of them are briefly described here. Each wood batch has a maximal life span. It cannot be transported before it is piled up, and regulations indicate