Selection of a lifting mechanism for a small-scale construction project: A comparative method based on building volume and an automated schedule

Abstract

The selection of construction machinery for a project is a very important part of the construction process. Rigorous preparation for construction is very often neglected in practice even though three fifths of the construction companies in the Czech Republic operate at prices that lie below the safe pricing threshold. For small-scale buildings this ratio is even more pronounced. This fact can be understood as meaning that the price of construction is undervalued in such a way that it also has a negative impact on construction safety. On the other hand, the selection of a lifting mechanism usually relies on the individual decision-making capabilities of the construction manager, and the decision is mostly based on the options that are locally available. In such cases, the result is often that the total cost is disproportionately high and/or the lifting mechanism is oversized. The proper selection of the main lifting mechanism for a project depends on many factors and criteria, such as crane position, load characteristics, economic criteria and the flexibility of the schedule. Effective lifting mechanism selection fundamentally depends on the definition of the economic and technological criteria for each individual structure at the beginning of the project. This paper presents an approach developed by the authors to assess the suitability of a lifting mechanism for small-scale construction work based on an automated schedule in combination with the volume of the structure. A case study comparing two types of small self-erecting crane and a mobile crane is presented in order to prove the usefulness of this method. The results include a graph from which the suitability or unsuitability of each individual mechanism can be found. A cost curve with a transition point depicted for a range of six small-scale structures with different building volumes is shown for each mechanism. A clear transition point was found at a building volume of 6030 m3.

The selection of construction machinery for a project is a very important part of the construction process. Rigorous preparation for construction is very often neglected in practice even though three fifths of the construction companies in the Czech Republic operate at prices that lie below the safe pricing threshold. For small-scale buildings this ratio is even more pronounced. This fact can be understood as meaning that the price of construction is undervalued in such a way that it also has a negative impact on construction safety. On the other hand, the selection of a lifting mechanism usually relies on the individual decision-making capabilities of the construction manager, and the decision is mostly based on the options that are locally available. In such cases, the result is often that the total cost is disproportionately high and/or the lifting mechanism is oversized. The proper selection of the main lifting mechanism for a project depends on many factors and criteria, such as crane position, load characteristics, economic criteria and the flexibility of the schedule. Effective lifting mechanism selection fundamentally depends on the definition of the economic and technological criteria for each individual structure at the beginning of the project. This paper presents an approach developed by the authors to assess the suitability of a lifting mechanism for small-scale construction work based on an automated schedule in combination with the volume of the structure. A case study comparing two types of small self-erecting crane and a mobile crane is presented in order to prove the usefulness of this method. The results include a graph from which the suitability or unsuitability of each individual mechanism can be found. A cost curve with a transition point depicted for a range of six small-scale structures with different building volumes is shown for each mechanism. A clear transition point was found at a building volume of 6030 m3.