This paper presents a two-echelon vehicle routing problem (2E-VRP) with vehicle synchronization at meeting points for the reverse logistic network to collect waste in the urban area. Low-capacity vehicles are utilized to perform collection only in the inner part of the city because of restricted access and limited infrastructure to be expanded. While, high-capacity vehicles are used to transform waste from the border of the inner city to the recycling centers located outside of city. Vehicles of the first and second echelons visit each other at meeting points, which do not have storage capacity mainly because of environmental and social consequences of the transshipment of waste. The timing aspect plays a critical role at meeting points to ensure the reasonable sequence of operations. So, temporal synchronization, a critical aspect of 2E-VRP, is considered in this paper, as well as minimization of waiting time of vehicles in meeting points to avoid long dwelling time. Moreover, because the previous study of 2E-VRP has not dealt with space limitation of meeting points, this paper presents a 2E-VRP that incorporates temporal synchronization, waiting time, and temporal capacity simultaneously for the first time to address a more practical model. To solve the mentioned problem a set of capable and latest metaheuristics are proposed as well as the hybrid ones to probe their efficiency and reasonably construct high quality routes. Moreover, the impact of the temporal capacity is investigated compared to temporal synchronization without considering temporal capacity.

中文翻译：

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垃圾收集系统中两梯队车辆路径问题的时空一体化同步

本文提出了一个两梯队车辆路径问题（2E-VRP），该问题在交汇点实现车辆同步，用于逆向物流网络收集城市地区的垃圾。由于通道受限且待扩建的基础设施有限，仅在城市内部使用低容量车辆进行收集。同时，使用大容量车辆将废物从内城边界转移到城外的回收中心。第一梯队和第二梯队的车辆在交汇点互相拜访，这些交汇点没有存储能力，主要是因为转运废物造成的环境和社会后果。时间安排在会议点起着至关重要的作用，以确保合理的操作顺序。因此，本文考虑了时间同步（2E-VRP 的一个关键方面），以及最小化车辆在交汇点的等待时间以避免长时间停留。此外，由于之前的2E-VRP研究没有解决交汇点的空间限制，因此本文首次提出了一种同时结合时间同步、等待时间和时间容量的2E-VRP，以解决更实用的模型。为了解决上述问题，提出了一组有效且最新的元启发法以及混合元启发法，以探讨其效率并合理构建高质量路线。此外，与不考虑时间容量的时间同步相比，研究了时间容量的影响。