## 2 Recent Trends in VRPs  
Knowing the importance of the VRP in the real world as it was depicted in the Introduction section, it is possible to highlight a long list of recent applications of routing models in many practical arenas. Some of the practical contributions of the VRP were historically presented by [PERSON] [15] and, more recently, by [PERSON] et al. [2]; this last reference envisioned the would-be VRP applications and models for the following years. In a parallel way, [PERSON] et al. [16] presented the green vehicle routing problem as a rich new paradigm that presented new challenges for supply chain management and transportation. Later, the general overview written by [PERSON] et al. [17] highlighted the importance of dynamic models in uncertain scenarios as the key problem for transportation and distribution problems in the near future. Furthermore, [PERSON] et al. [18] offered a detailed description of the current taxonomy of dynamic VRPs and their relationship with applied problems in the real world. Apart from the previous dynamic scenarios, the novel paradigm of urban mobility based on non-internal-combustion vehicles (mainly electric vehicles) has suggested the need for the design of dynamic VRP models adapted to city logistics [19]. Hence, we can currently consider the following great topics as critical in the design and use of dynamic VRP models:  
* Minimization of pollutant emissions: The problem of minimizing pollutant emissions in routing, which is included in the green vehicle routing problem, was profiled in the period of 2005-2010. Even though the complete analysis is still in progress, this represents an essential challenge in current mobility paradigms [20]. This topic lies on the basis of the three typical sustainability dimensions of the VRP--the economic, environmental, and social dimensions--which are now omnipresent in the transporta  
Figure 2: List of journals that published articles on VRPs under uncertainty or in dynamic scenarios. tion and routing literature [21]. Usually, the environmental and social dimensions are considered key externalities associated with transportation [22]. * Consideration of social issues related to transportation: In the last decade, the social externalities due to transportation--e.g., congestion, pollutant emissions, noise, infrastructure wearing, etc.--have been revealed as critical in the way of designing sustainable modes of mobility [21; 22; 23]. These traits also assume a very dynamic behavior in mobility problems, which should be contemplated in VRP modeling. * Greater importance of the urban scenarios: Knowing the importance of the previously mentioned sustainability dimensions, in recent years, it has become clear that the urban arena is the key location in which those dimensions present their critical facets [24]. Urban mobility problems need the support of agile procedures more and more [25]. * Increase in scenarios based on accidents and catastrophes: Due to the higher demand for transportation and mobility, along with an increase in requests for logistic support in disaster scenarios [26], the quicker responses and solutions have been revealed as essential [27]. * Greater importance of energetic objectives and constraints in the transportation programs: It is clear that most of the new challenges that transportation is going to face are going to be related to energy, not only for the use of more sustainable means of mobility, but also for the need to optimize consumption and production [28]. * Necessity of collaboration as a way of facing complex distribution processes: Collaborative and cooperative approaches are becoming quite common in goods and merchandise distribution [29]. They allow for good performance in the sustainability dimensions, as presented by [PERSON] et al. [30]. Finally, the dynamic VRP was contemplated by [PERSON] et al. [31].