Epsilon Archive for Student Projects

Abstract

The need for roundwood transport capacity vary throughout the year. The need during a period is influenced mainly by the volume transported the period, the number of days during which transport can be carried out, seasonal variations in road conditions and the weight of the roundwood, and the origin of the wood (private forest owners/ forest companies). The need for transport capacity generally increase during the winter and in spring, after thawing. Lack of logging trucks combined with a lack of drivers for these trucks make it hard to hire extra help during periods of increased transport capacity needs. It is also very expensive to keep logging trucks for use only during these periods.

In this thesis, two new concepts based on the partial transport by truck tractors have been examined, to find out the possibility for increased performance and flexibility. Concept 1 uses load exchange sites as the breaking point between logging trucks and truck tractors. The roundwood transport from the forest to the load exchange site uses logging trucks with attached dollys and semitrailers. At the load exchange site, the wood pile on the logging truck is reloaded to a link, which is then connected to the semitrailer. The link and semitrailer are then transported to the paper, pulp or sawmill using a truck tractor. Concept 2 uses an ordinary terminal as the breaking point, and roundwood transport from forest to terminal is carried out by regular logging trucks, which drop off the entire load at the terminal. Transport from terminal to industry is carried out by truck tractors and semitrailer.

Two different models were designed. Both were based on balancing the ingoing and outgoing wood flows to the load exchange site or terminal, to avoid any increase or decrease of stock in the terminal or to create a stock at the load exchange site. In concept 1 the waiting periods were limited to a maximum of 10 minutes.Both models could be applied, using combinations of 1-3 logging trucks and 1-3 truck tractors. At system level there were 12 logging trucks available.

For concept 1 a doubling of flexibility is possible to manage. For concept 2 there can be an increase of flexibility by one fifth. However, for Concept 1, the minimization of waiting periods leads to restrictions in possible distances from forest to load exchange sites. Transport planning will also be affected by Concept 1, since the fitting loading sites must be chosen several weeks in advance. Concept 2, on the other hand, will not alter transport planning much, as it quite similar to traditional use of terminals.

Kapacitetsbehovet vid rundvirkestransport varierar över året. Behovet per period påverkas främst av transportvolym, antal arbetsdagar under perioden, årstidsvariation i väglag och virkesvikt samt andelen virke från privat- respektive bolagsskog. Generellt är behovet störst vintertid samt efter tjällossning. Virkesbils- och chaufförsbrist gör det svårt att hyra in extrahjälp vid ökat kapacitetsbehov. Att ha virkesbilar som endast nyttjas vid ökat behov är kostsamt.
Två nya koncept, där transporten delvis sker med dragbil, har undersökts för att fastställa möjlig prestations- och flexibilitetsökning. I koncept 1 nyttjas rangerplatser, dit transport från skog sker med virkesbil med tillkopplad dolly och semitrailer. På rangerplatsen lastas virkestraven på virkesbilen över på en link, vilken kopplas samman med semitrailern. Detta transporteras vidare till industri med dragbil. I koncept 2 nyttjas en sedvanlig virkesterminal, dit transport från skog sker med konventionella virkesbilar som lastar av hela lasset. Vidaretransport till industri sker med dragbil och semitrailer.
Två modeller konstruerades med syftet att hitta balans mellan virkesflöde till och från rangerplats respektive terminal. För koncept 1 begränsades väntetider till maximalt 10 minuter. För båda modellerna kunde kombinationer av mellan 1-3 av vardera virkesbilar och dragbilar nyttjas. På systemnivå fanns 12 virkesbilar tillgängliga.
För koncept 1 är fördubbling av flexibiliteten möjlig, medan det för koncept 2 kan ske en ökning med upp till en femtedel. Dock innebär väntetidsbegränsningen hos koncept 1 begränsningar i avstånd skog – rangerplats. Transportplaneringen vid nyttjande av koncept 1 påverkas då trakter på lämpliga avstånd måste väljas i förväg. Vid koncept 2 blir transportplaneringen lik den vid traditionell körning mot terminal