Kvalitet på vägdata : inventering av skogsbilvägars standard samt jämförelser med lokal bedömning och SNVDB

Abstract: During 2006 SNVDB (the national road data base for forestry) is being introduced to Holmen Skog. This data base contains all information about Holmen Skogs road systems. The information will then be used in different kinds of optimisation models which only produce correct and reliable results if the input data are of the adequate quality. Today there are reasons to believe that road data is of various qualities. The forest roads are often in a bad condition and have to be improved before a planned harvest. The cost of maintenance and construction of new roads is a large part of the total harvesting cost. To reduce the harvesting costs, road maintenance have been neglected. Another reason to suspect various qualities of road data is that Holmen is a geographically widespread company. The geological and meteorological conditions for a road in the southern region are far different from the conditions in the northern regions. The most probable reason for misleading road data is however that different people make different judgements based on different criteria. Today there are no standardized guidelines how to classify roads. There are also very few people inside Holmen Skog who have the knowledge and experience to make reliable estimations about road condition. The aim of this study was to compare the road standard (bearing capacity) classification according to SNVDB and local evaluation/register with the standard according to a formal inventory for a sample of roads in Holmen Skog forests. The study also investigates what any differences between these three classifications may be caused by. For the inventory classification, the whole road has first viewed from the car. Then the weakest section was classified according to soil type, material in the top section and damage/defects. The inventory classification was then compared with the classification according to SNVDB and local estimation in each of Holmen Skogs four regions. The results of the study show that there are large differences in road standard classification between local estimation, SNVDB and the inventory done in this study. This means that the data should not be used in optimisation models until it is controlled and adjusted. There are major differences in how forest roads are classified and a more homogenous classification system with standardised criteria is necessary.