The Accuracy of Snapshot Observations in Determining the Structure of Tree Harvester Operating Times

Traditional time study methods are time-consuming and expensive and require experienced staff. Using a time sampling methodology based on video recordings might be a time-efficient and precise solution. This study scrutinized the accuracy and margin of error for various snapshot lengths and types (fixed and variable) when estimating the operating times of a tree harvester in clearcuts and thinnings of Scots pine stands. The study focused particularly on the impact of type, recognizing its potential to influence the accuracy of the estimates. The study examined interval lengths of 3–20 s (in 1 s increments), as well as 25, 30, and 35 s, in two types (fixed and variable length). While both the type and length of an interval affected the obtained levels of errors (particularly the mean absolute percentage error—MAPE), the random-length type usually resulted in a higher level compared to the fixed-length of the same length. The proportion of operating times did not differ from that obtained by a continuous time study for all lengths and types, for both thinnings and clearcuts. As fixed-length interval studies are much easier to conduct and result in lower error levels, it is recommended that the fixed-length intervals (up to 19 s in thinning and 17 in clearcuts) are used for this type of study.