A timber extraction method based on pavement serviceability and forest inventory data

Abstract

A methodology for integrating pavement classification and forest inventory data to determine the capability of forest access roads with weak subgrades to support timber extraction is described. GPS location data recorded in stand-alone mode was superimposed on forest and Ordnance Survey maps. Within a GIS, the acquired spatial data was manipulated and integrated with pavement attribute information and the current and projected forest inventory data. Potential pavement damage by a typical timber haulage truck with payloads of 22, 27, 30, and 35 tonnes (t) was then assessed. It was found that by overloading the truck by 3 and 8 t (GVW of 43 t and 48 t, respectively), the total volume of timber that could be conveyed without damaging the serviceable pavements reduced by an average of 16 and 44%, respectively. Rerouting of timber to avoid critical and failed sections could significantly increase the transportation costs. Rerouting was found to be impractical where forest compartments were accessible by single routes; hence, necessary repairs to facilitate the extraction are recommended in such cases. The final database could be extended to include specific costing of repair and maintenance requirements, and so determine the economic implications of respective routing strategies.