Reduction of queuing delays at waste management facilities

ile waiting to unload materials at waste management facilities such as landfill sites, transfer stations, and material recovery facilities. These delays can be costly since the program operator must pay for these trucks and their crews to sit idly. Previous studies of delays at unloading facilities have often focussed on reducing unloading times, primarily through capital improvements such as providing twin scale houses and additional unloading bays. Most of these studies assume that the "arrival pattern of the collection vehicles is beyond the control of the analyst. This work assumes that the physical layout of the unloading facility is fixed and examines the effect that changes in the arrival times of collection vehicles will have on queuing delays at the facility. Both deterministic and fluid flow approaches to the analysis of queuing delays at unloading facilities are presented. The results show that congestion at unloading facilities is often caused by the assignment of approximately equal workloads to each collection crew and that relatively minor differences in workload assignments can substantially reduce queuing delays. The results of the analysis are confirmed through Monte Carlo simulation modelling.