Comments on: Routing problems with loading constraints

Vehicle routing problems are among the most applicable and applied models of operations research in the economically important area of logistics. Due to their inherent high complexity, even for the most simplified model-formulations it often remains intractable to solve exactly realistically sized instances, and therefore they have and still are one of the important sources of hard problem-types for heuristic approaches to tackle. On the other hand, the requirements from the logistics industry call for consideration of various additional constraints adding many new layers of complexity, thereby pushing research into the metaheuristic field to new heights in order to meet these challenges. Examples of already well-studied extensions are time-windows, real-time dynamic call situations, pickup and delivery, etc.