Resource and time criticality based block spatial scheduling in a shipyard under uncertainty

Abstract

The block erection area is an important bottleneck resource that determines the throughput and productivity of a shipyard. This study addresses Block Spatial Scheduling (BSS) problem of a shipbuilding project comprising 72 blocks with uncertain erection duration. We adopted priority rules-based simulation approach to overcome the computational complexity of non-deterministic polynomial hard BSS problem. This is one of the earliest studies to introduce resource (space) based criticality index in BSS problem. Four time-based, one resource-based and six combinations of time criticality index (TCI) and resource criticality index (RCI) based priority rules are considered for achieving three objectives: minimisation of expected project duration, minimisation of expected average tardiness of blocks and maximisation of average area utilisation percentage. Seven important implications are derived from results, which can be applied by shipbuilding managers to BSS to increase the productivity of shipyard. Results reveal that priority rule based on TCI×RCI and shortest processing time yield the most and the least efficient trade-off, respectively, between time and resource-oriented objectives. Further, a sensitivity analysis, performed by varying degree of uncertainty, reveals negative effect of uncertainty by increasing variation in objectives. Overall, the derived implications underpin the importance of incorporating RCI in BSS context.