Utvärdering av CTI på virkesfordon : CTI-projekt Holmen Skog/Örnfrakt 2005-2006

Sammanfattning: The low bearing capacity of roads during the spring thaw and periods in the autumn leads every year to increases costs for Holmen Skog. To reduce costs and increase accessibility Holmen Skog decided to install and test a CTI-system. Central tire inflation (CTI) is a system that makes it possible to monitor and vary a vehicle's tire inflation pressures from the cabin, while the vehicle is in motion. When tire pressures are reduced, the area of the contact surface between the tire and the road increases, thus reducing the ground pressure. The purpose of this study was to evaluate the CTI-equipped vehicle and analyze if the CTI technology is economical defensible during the thaw 2005. The study consisted of three parts. First, a follow-up of the CTI-equipped vehicle that consisted of a rutting depth study and interviews with the drivers in the CTI-truck. Secondly, a calculation was made to evaluate potential savings. At last, a calculation was made to compare the economy between the CTI-equipped vehicle and a conventional timber transport vehicle. The rutting-depth study conducted late in the spring showed that the road damage is reduced and the mobility is increased when the tire pressure was reduced. The combined experience from the drivers were also that the CTI system contributed to softer ride, which lead to better working environment and reduced wear on tires and vehicle. Theoretically, the transport cost can decrease with 0,5 % if the CTI-equipped vehicles are allowed to carry full payloads on roads that have restrictions of maximum 30 tonnes payload. The study also showed that the machine utilization increased with 1-2 %. The economical comparison between the CTI-equipped vechicle and a conventional timber transport vehicle showed a cost reduction of 4-6 % per hour for the CTI-truck when the CTI systems positive effects were taken in consideration.