Location optimization of tower crane and allocation of material supply points in a construction site considering operating and rental costs

The choice of a suitable tower crane along with its location may considerably affect the costs and duration of the construction process. The location of the tower crane determines the travel time of transporting material between the supply and demand points and thus the operation costs. On the other hand, the distance between the tower crane and supply points as well as the distance between the tower crane and demand points considerably affects the minimum required load moment capacity of the cranes and thus the cranes' rental and operating costs. Previous studies on optimizing the location of tower cranes on a construction site have focused mainly on minimizing the crane operation costs through minimizing their operation time, overlooking the effect of tower crane location on its required capacity and thus rental and operation costs. This paper presents a modified crane location optimization model that also accounts for the effects of crane location on its required capacity, on top of operating time, when minimizing the total costs of lifting operations. A mixed-integer programming model is developed and applied to an actual case study to illustrate the importance of accounting for the effect of crane location on its required capacity in crane location optimization. Furthermore, using a hypothetical case study, the presence of substantial differences between the weights of the elements required at different demand points is identified as an important project-specific parameter affecting the magnitude of the errors occurred by overlooking the capacity requirements and its effects on rental and operating costs in the crane location optimization problem.