The vehicle routing and scheduling problem has been studied with much interest within the last four decades. In this paper, some of the existing literature dealing with routing and scheduling problems with environmental issues is reviewed, and a description is provided of the problems that have been investigated and how they are treated using combinatorial optimization tools.
Although the fact that the major target of RHM is the minimization of the risk, there is no universally accepted definition of risk (for a survey on risk assessment, see @cite_89 ). The risk caused by hazmat transportation depends on many factors, the most important of which are: the risk categories (explosion, toxicity, radioactivity, etc), the transportation mode, the affected agents (population, territorial infrastructures and natural elements), the meteorological conditions and the temporal factor. It is pointed out in @cite_48 that the evaluation of risk in hazmat transportation generally consists of the evaluation of the probability of an undesirable event, the exposure level of the population and the environment, and the degree of the consequences (e.g., deaths, injured people, damages). In practice, these probabilities are difficult to obtain due to the lack of data and generally, the analysis is reduced to consider the risk as the expected damage or the population exposure.
@cite_48 @cite_89
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Transportation of hazardous materials (hazmats) is a decision problem that has been attracted much attention due to the risk factor involved. A considerable amount of models have been developed that employ single or multiple objective shortest path algorithms minimising the risks for a given origin-destination pair. However in many real life applications (i.e. transportation of gas cylinders), transportation of hazmats calls for the determination of a set of routes used by a fleet of trucks to serve a set of customers, rather than determination of a single optimal route as shortest path algorithms produce. In this paper, we focus on population exposure risk mitigation via production of truck-routes by solving a variant of the Vehicle Routing Problem. For this purpose we employ a single parameter metaheuristic algorithm. A case study of this approach is also demonstrated. The transport of hazardous materials is an important strategic and tactical decision problem. Risks associated with this activity make transport planning difficult. Although most existing analytical approaches for hazardous materials transport account for risk, there is no agreement among researchers on how to model the associated risks. This paper provides an overview of the prevailing models, and addresses the question "Does it matter how we quantify transport risk?" Our empirical analysis on the U.S. road network suggests that different risk models usually select different "optimal" paths for a hazmat shipment between a given origin-destination pair. Furthermore, the optimal path for one model could perform very poorly under another model. This suggests that researchers and practitioners must pay considerable attention to the modeling of risks in hazardous materials transport. Undesirable consequences of dangerous goods incidents can be mitigated by quick arrival of specialized response teams at the accident site. We present a novel methodology to determine the optimal design of a specialized team network so as to maximize its ability to respond to such incidents in a region. We show that this problem can be represented via a maximal arc-covering model. We discuss two formulations for the maximal arc-covering problem, a known one and a new one. Through computational experiments, we establish that the known formulation has excessive computational requirements for large-scale problems, whereas the alternative model constitutes a basis for an efficient heuristic. The methodology is applied to assess the emergency response capability to transport incidents, that involve gasoline, in Quebec and Ontario. We point out the possibility of a significant improvement via relocation of the existing specialized teams, which are currently stationed at the shipment origins. For survival, a living agent (e.g., human in Fig. 1(a)) must have the ability to assess risk (1) by temporally anticipating accidents before they occur (Fig. 1(b)), and (2) by spatially localizing risky regions (Fig. 1(c)) in the environment to move away from threats. In this paper, we take an agent-centric approach to study the accident anticipation and risky region localization tasks. We propose a novel soft-attention Recurrent Neural Network (RNN) which explicitly models both spatial and appearance-wise non-linear interaction between the agent triggering the event and another agent or static-region involved. In order to test our proposed method, we introduce the Epic Fail (EF) dataset consisting of 3000 viral videos capturing various accidents. In the experiments, we evaluate the risk assessment accuracy both in the temporal domain (accident anticipation) and spatial domain (risky region localization) on our EF dataset and the Street Accident (SA) dataset. Our method consistently outperforms other baselines on both datasets.