Utvärdering av Hultdins prototyp för portabel bro (drivningsbro)
Stronger demand has been put on forestry to show environmental considerations during harvesting. This is especially for crossings of brooks with sensitive elements and great care should be observed when they are to be crossed during harvesting by logging machines. For that reason Hultdins has constructed a portable bridge that can be used for those occasions. The bridge has been developed in accordance with wishes from SCA forest, since they have a great deal of brooks in their forests and in private forests from where they buy part of their wood supply.
The aim for this report is to investigate if this portable bridge can be of interest for the forestry market. The research has been made at SCA skog in Medelpad and Norrskog in Medelpad. A survey was been made among categories of working teams as production leaders, entrepreneurs of forest machines, wood buyers and supervisors for nature conservation. Their opinions vary but all had a positive attitude to the portable bridge.
The entrepreneurs told that they had on average built bridges to cross brooks one of five harvests in the past period. It took them on average 20 minutes to build a timber bridge. This can be compared with the portable bridge witch it takes 5-10 minutes to lay out.
The operational leader?s answers indicated a possible interest (11%) to change winter posts to summer posts when using a portable bridge. How many SEK/m3fub it was possible to gain with such shift only three persons answered and thought they could gain 32 SEK/m3fub, since prices for wood is higher in summer time. All persons were positive towards this solution considering that planning would be easier and less damage would occur during operation.
Wood buyers answered that on advantage in 14 % of the cases it would a benefit to offer a portable bridge when buying wood. The buyer thinks the landowner would gain about six meter per cubic metre. Five of six buyers thought it was possible to buy more wood if one offers a portable bridge when buying wood. The buyers estimated the amount of wood used for building bridges could be 16 m3fub worth 2 700 SEK when buying wood.
Supervisors for environmental care gave only viewpoints concerning the consideration shown in relation to brooks. They thought that the responsibility was taken seriously and decent among the operators, and that there were no problems of combining nature conservation with production. How many SEK/m3fub one could earn with the portable bridge in terms of nature conservation, no one wanted to answer, since nature conservation cannot be measured in money. The also thought the use of a portable bridge will be used in the future considering increased careful harvesting must be done when there is no snow on the ground.
On average this study showed that a portable bridge from Hultdins can prevent harm on land and sensitive water systems. It also gives economic gains, considering both operational leaders and wood buyers viewpoint. With a possible long life span for this bridge, it should be profitable in a long term perspective.