Optimization of multiple-crane service schedules in overlapping areas through consideration of transportation efficiency and operational safety

Abstract

Tower crane scheduling is a classic conundrum. It is further complicated to prevent collisions and reduce idle transportation time among multiple overlapping tower cranes. Unlike previous research attempts, this study aims to provide an optimal solution to this multiple crane service scheduling problem (MCSSP). Firstly, the MCSSP was translated to a Mixed Integer Linear Programming (MILP) model. Then, the model was optimized by 1) distributing the lifting requests in overlapping areas to the proper tower cranes; 2) selecting the appropriate supply location to serve each lifting request; and 3) arranging the lifting sequences of each tower crane to complete the requests. Compared with previous methods, the proposed MILP model (solved using Gurobi™) can result in the saving of 6.54%–18.07% of total operation costs meanwhile achieving the non-collision goal. The findings of this research can be deployed in optimizing efficiency and safety in the real-life scheduling of multiple overlapping tower cranes.