Analysis of construction sub-processes for the evaluation of the real performance of tower cranes

The productivity of work performed at construction sites is primarily dependent on the effective deployment and use of construction machinery. Nevertheless, manufacturers do not state the actual performance of their machinery because it is difficult to determine due to its dependence on the specific conditions present at each construction site. One of the most important machines used in the construction of buildings is the tower crane, which provides secondary transport of material onsite. In order to evaluate the effectiveness of the use of such machines using a deterministic or stochastic approach, a relatively extensive and exact set of data describing the activities of a given tower crane needs to be prepared. These data describe the real requirements of ongoing construction sub-processes with regard to the utilisation of tower cranes. This contribution concerns the analysis of key construction sub-processes during the building of monolithic reinforced concrete structures in connection with secondary transport at the construction site; in particular, it describes the preparation and processing of this data for the evaluation of real time requirements placed on tower cranes.

Predicting productivity of timber loading operations: a literature review

Loading is considered a bottleneck of the forest harvesting system as it acts as a connection between primary transport and secondary transport (from roadside/ landing to mills or central yards). Any delay during the loading component can cause delay in the primary wood extraction and/ or secondary transportation. This article reviewed the current knowledge on loading productivity studies. Based on the results, the main variables impacting the loading productivity include log size, log lengths, load volume per truck, number of logs (or pieces) per truck and number of safety straps. The productivity of loading operations ranged from 3.4 m3/PMH0 in a manual loading to 168.9 m3/PMH0 using mechanised loaders. The results of this review can assist the academic and industrial users for predicting, controlling and managing the productivity of loading operations.