In this work we consider the following hazmat transportation network design problem. A given set of hazmat shipments has to be shipped over a road transportation network in order to transport a given amount of hazardous materials from specific origin points to specific destination points, and we assume there are regional and local government authorities that want to regulate the hazmat transportations by imposing restrictions on the amount of hazmat traffic over the network links. In particular, the regional authority aims to minimize the total
transport risk induced over the entire region in which the transportation network is
embedded, while local authorities want the risk over their local jurisdictions to be the lowest possible, forcing the regional authority to assure also risk equity. We provide a linear bilevel programming formulation for this hazmat transportation network design problem that takes into account both total risk minimization and risk equity. We transform the bilevel model into a single-level mixed integer linear program by replacing the second level (follower) problem by its KKT conditions and by linearizing the complementary constraints, and then we solve the MIP problem with a commercial optimization solver. The optimal solution may not be
stable, and we provide an approach for testing its stability and for evaluating the range of the its solution values when it is not stable. Moreover, since the bilevel model is difficult to be solved optimally and its optimal solution may not be stable, we provide a heuristic algorithm for the bilevel model able to always find a stable solution. The proposed bilevel model and
heuristic algorithm are experimented on real scenarios of an Italian regional network.

A Bilevel flow model for HazMat transportation network design

Transporting hazardous materials (HAZMAT) often involves multiple modes, especially for long-distance transportation. Based on the recent US Commodity Flow Survey data, the amount of HAZMAT transported by multiple modes has increased from 18.7 million tons in 2002 to 111.0 million tons in 2007. However, not much research has been conducted on multimodal HAZMAT transportation. Most existing studies focus exclusively on single-mode (either highway or railway) HAZMAT transportation, investigating topics such as vehicle routing and scheduling, network design, facility location, and risk analysis. Motivated by the lack of research on multimodal HAZMAT transportation and the fact that there is an increasing demand for it, this research proposes a multimodal HAZMAT model that simultaneously optimizes the locations of transfer yards and transportation routes. The developed model is applied to two case studies of different network sizes to demonstrate its applicability. The results are analyzed and suggestions on future research are provided.

Multimodal Location and Routing Model for Hazardous Materials Transportation

/pdf/a-review-of-train-delay-prediction-approaches-1gvmcazs.pdf

A review of train delay prediction approaches

The symmetry concept is mainly used in two senses. The first from the aesthetic point of view of proportionality or harmony, since human beings seek symmetry in nature. Or the second, from an engineering point of view to attend to geometric regularities or to explain a repetition process or pattern in a given phenomenon. This special issue dedicated to geometry in engineering deals with this last concept, which aims to collect both the aspects of geometric solutions in engineering, which may even have a certain aesthetic character, and the aspect of the use of patterns that explain observed phenomena.

https://www.mdpi.com/2073-8994/11/6/797/pdf

Symmetry in Engineering Sciences

Modeling the effects of leakage in the transport of hazardous liquids is a highly topical issue, not only in the field of environmental engineering. This article’s introduction presents relevant information and statistical sources, analyzes selected scientific and professional publications, and characterizes the results of selected research projects. The applied approaches, methods, and results of our research specify the processes of developing and testing a theoretical model of spreading the impacts of leakage of hazardous liquids on biological components of the environment. The proposed model for predicting the environmental impacts of hazardous liquid (HL) leakage during transport is a crucial risk management tool in the planning of transport of dangerous goods. It also enables the creation of comprehensive information systems that monitor the transport unit in real-time, indicate the presence of significant habitats along the transport route, and draw attention to possible threats, in particular to the health and lives of people and the environment. The main result of the presented research is the application of a computational model for determining the parameters of the dangerous zone in case of HL leakage and its graphical plotting along the transport route, estimating the probability of impacting the selected place by leaking HL. The model application results are presented in the form of calculated frequency of impacting the set of points in the vicinity of the HL transport route. Defined standardized frequencies of HL infiltration above a specified limit in liters per square meter in the event of leakage of the entire volume of HL from a road tanker (leaked volume of 30 m3) form the basic set of information for creating relevant risk maps near busy traffic routes and subsequent selection of ecologically and spatially optimal routes.

Environmental Impact Modeling for Transportation of Hazardous Liquids

Hazardous materials (HAZMAT) are important for daily production in cities, which usually have a high population. To avoid the threat to public safety and security, the routes for HAZMAT transportation should be planned legitimately by mitigating the maximum risk to population centers. For the objective of min-max local risk in urban areas, this study has newly proposed an optimization model where the service of a link for HAZMAT transportation was taken as the key decision variable. Correspondingly, the symmetric problem of min-max optimization takes significant meanings. Moreover, in consideration of the work load of solving the model under a lot of decision variables, a heuristic algorithm was developed to obtain an optimal solution. Thereafter, a case study was made to test the proposed model and algorithm, and the results were compared with those generated by deterministic solving approaches. In addition, this research is able to be an effective reference for authorities on the management of HAZMAT transportation in urban areas.

https://www.mdpi.com/2073-8994/11/9/1091/pdf

Routing for Hazardous Materials Transportation in Urban Areas

The invention provides a train section delay prediction error control method, which belongs to the technical field of rail transit operation control, and comprises the following steps of: firstly, determining a state variable for describing a train section delay prediction error, and establishing an ordinary differential equation set for describing the train section delay prediction error; constructing a delay prediction error cascade control model according to the ordinary differential equation set; secondly, determining optimal control parameters of the delay prediction error cascade controlmodel through a method of combining an artificial fish swarm intelligent algorithm and an SIMULINK simulation tool; and finally, minimizing train arrival time prediction errors and departure time prediction errors of the current station and the previous station according to the optimal control parameters. According to the method, a new analytical optimization process is introduced, the control theory is applied to the train section delay prediction error problem, and automatic control reduction of the train section delay prediction error is achieved.

Train section delay prediction error control method

Delay prediction is significant for the well-organised operation of trains. Meanwhile, the accurate prediction is interfered by comprehensive factors in practice, hence there are always quite a few predicted errors due to cascading effect in operation. This study newly proposes a method based on state-space equations to mitigate errors of predicted delays of a train at neighbouring stops. A linear quadratic regulator for reducing errors is developed from modern control theory. Moreover, necessary derivation and proof processes are made to support the method. An artificial fish swarm algorithm is designed to determine necessary parameters of the regulator, and the corresponding simulation is achieved by the SIMULINK architecture. The new method is able to be an effective reference for theoretical innovation and practical application in the operation of railway systems.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-its.2019.0365

Mitigating errors of predicted delays of a train at neighbouring stops

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Routing for Hazardous Materials Transportation in Urban Areas

Train section delay prediction error control method

Mitigating errors of predicted delays of a train at neighbouring stops