Quantitative analysis of blind tower-crane lifts using laser-scanning information

Purpose – This study aims to show how laser scanning data can be utilised to quantitatively assess “blind lifts” with respect to their rate and spatial distribution. Design/methodology/approach – This study employed time study of crane cycles for quantitative measuring of the crane’s work periods in dead areas and mapping the crane operator’s field of view and developing a model that allows the spatial analysis of blind lifts. Findings – This study found a discrete geometric laser scan-based model that is capable of locating and quantifying the visible and invisible zones from the crane operator’s cabin; 28 per cent of the analyzed crane’s work area represented by the model were found to be invisible, which corresponds fairly to 35 per cent of the half-cycles measured manually that were found to involve blind lifting; the range of blind lifts duration derived from the spatial information-based model was 50 to 84 per cent, which is in excellent correspondence with the 54 per cent to 82 per cent range obtained from the time unit-based analysis. Research limitations/implications – The laser-based model and the ensuing analyses are limited to the type of buildings whose envelope can practically be represented by the vertical extrusion of their footprint. Practical implications – The practical implications of the study are reduction of blind lifts as a factor when selecting the location of the crane and staging areas; more effective preplanning of signallers positioning; and ad hoc consideration of analysed dead space for various lift task-based decision-making during construction. Originality/value – This study demonstrates the ability to capture the geometric relations that characterise the work scene around the tower crane by harnessing the increasingly available laser technology and correlates the results of the manual observations with those obtained from the laser-based model.