A high-quality data set for forest truck roads is an important prerequisite for road infrastructure management and transport route selection, as well as for the analysis of the ecological impact and recreational use of these roads. To support management decisions, the data set needs to fulfil various quality requirements, such as accuracy, relevance (fitness for use), consistency and completeness. In this section, we introduce the steps necessary to produce a reliable forest road data set, following a clearly defined procedure to ensure reproducibility, as well as consistency for the entire country and between inventory cycles. Furthermore, we point out potential error sources and how the Swiss National Forest Inventory (NFI) tries to avoid them, choosing appropriate measures for error prevention as well as error detection and adjustment of methods.