The paper considers the design of a multimodal and multilayer inbound logistics network for iron ore to be delivered from suppliers to steel plants. To make cost-efficient logistics and ...transportation planning decisions, steel companies should account for uncertainty in the demand for iron ore and the economies of scale during transshipment process in the port, which are two critical elements affecting decisions. To this end, we propose a two-stage nonlinear stochastic programming model with the first stage determining the choice of the port to perform transshipment operations and the needed capacity, and the second stage selecting transportation modes after demand uncertainty has been realized. To solve this problem, we first reformulate and linearize the model based on a quantity discount policy applied to the transshipment ports, and then, we develop a scenario-based decomposition algorithm. We conduct a case study based on the data of a steel company in China to illustrate the applicability of our proposed model. Moreover, we perform numerical experiments to demonstrate the effectiveness of our algorithm.
The study of how people jointly use different travel means is one of the key issues in contemporary transport research. However, measuring multimodality behaviours presents some intricacies that ...deserve more attention in order to come up with an instrument that is effective both on a modelling and on a policy viewpoint. The present work considers some methods that have been proposed in different disciplinary ambits to measure diversity and assesses to what extent they are useful to measure multimodality. A broad set of indices is then analysed, ranging from welfare economics (Gini, Dalton and Atkinson indices) to information theory and ecology (entropy, Herfindahl index). Theoretical investigations and empirical experiments on the properties of such indices show that there is not a measure of multimodality that consistently outperforms all the others in any circumstance. On the other hand, it emerged that some methods are clearly preferable for specific problem instances, as discussed in the conclusions.
Many public transport services receive operating subsidies from national, regional, or local Governments, part of which are directed to reducing fares. In recent years, different cities, most of them ...located in Europe, have advanced in the provision of free-fare public transport, which could help reduce car use and thus limit negative externalities related to its use. Using cost minimization models with variable mode share, in a circular structure with radial lines, optimal fares for bus services were estimated for 33 small and medium-sized cities in Chile. Through a linear regression model, we determined that the optimal fares decrease for cities with higher population, lower average income, a higher proportion of students, and with a CBD surrounded by natural boundaries such as seacoast. Based on the model's results, together with feasibility criteria that included competition of buses with other transportation modes, the regulation of existing systems and the quality of available data, recommendations are provided to select the best cities for a test of free-fare public transport in Chile. The methodology is applicable to cities in other countries, and future research may incorporate the effect of the valuation of crowding by users, as well as the generation of additional trips due to a drop in bus fares.
The protection of pedestrians, cyclists, and public transportation passengers from environmental pollution is a global concern. This study fills the gap in the existing knowledge of temporal exposure ...to air pollution in Latin American metropolises. The paper proposes a methodology addressing the relationship between two objects of study, i.e., the users of active modes of transport and air quality. This new methodology assesses the spatiotemporal concurrence of both objects with statistical analysis of large open-access databases, to promote healthy and sustainable urban mobility. The application of the empirical methodology estimated the number of users of active transportation modes exposed to poor air quality episodes in the Guadalajara metropolitan area (Mexico) in 2019. The study considered two pollutants, ozone (O3) and particulate matter (PM10), and two active modes, cycling and bus rapid transit (BRT). Spatiotemporal analyses were carried out with geographic information systems, as well as with numeric computing platforms. First, big data were used to count the number of users for each mode within the area of influence of the air quality monitoring stations. Second, the number of air pollution episodes was obtained using the air quality index proposed by the Environmental Protection Agency (USA) on an hourly basis. Third, the spatiotemporal concurrence between air quality episodes and active mode users was calculated. In particular, the air quality monitoring data from the Jalisco Atmospheric Monitoring System were compared to users of the public bicycle share system, known as MiBici, and of a bus rapid transit line, known as Mi Macro Calzada. The results showed that the number of cyclists and BRT passengers exposed to poor air quality episodes was considerable in absolute terms, that is, 208,660 users, while it was marginal when compared to the total number of users exposed to better air quality categories in the study area, who represented only 10%. To apply the results at the metropolitan scale, the spatial distribution of the air quality monitoring system should be improved, as well as the availability of data on pedestrians and conventional bus passengers.
In this paper an original approach for setting taxi fares is proposed. The approach is based on origin-destination fares and aims to increase the equity of transportation supply in an urban area: ...routes in certain urban areas can be very well served while others may be served poorly or not at all. Yet most citizens contribute indirectly to transit systems that are often subsidized to a considerable extent by public money. The proposed method seeks to balance this asymmetry, reducing taxi fares on origin-destination pairs that are poorly served by other transportation modes. An optimisation problem based on this principle is formulated and solved. The proposed approach is tested on a small test network and on a real-scale network. Numerical results show that the approach is applicable and useful to enhance equity in transit services.
•An origin-destination method for defining taxi fares is proposed.•The objective of the pricing structure is to increase the equity of the transportation supply.•The proposed method is formulated with an optimisation model and solved.•The method is tested on a small test network and on a real-scale network.•Numerical results show the applicability of the method and its financial sustainability.
•The attractiveness of Shanghai as a gateway to its hinterland over 31 provinces is measured.•It is empirically explained by transport facilities, geographical condition and location.•Seaport has the ...highest positive impact, followed by waterway, highway, and airport.•The impact of rail is negative until certain limit, showing a U-shaped distribution.
This paper analyzes the spatial–temporal evolution of the attractiveness of a country’s gateway for its international trade, using Shanghai as an example. The attractiveness is regressed on the transportation facilities and geographical conditions. Seaport development is found to have a major positive impact, followed by inland waterway, highway, and airport development. These positive impacts decrease with the need for highway haulage and with the distance from Shanghai—showing an inverse U-shape distribution. Rail appears to have a U-shape distribution, implying a low application of multimodal transportation. A geographical pattern for the impacts of different transportation modes is delineated.
This paper studies to what extent subway demand increased after the Beijing city government imposed restrictions on private driving in October, 2008. Utilizing a pseudo-repeat sale approach in a ...short sample period that includes 6months before and after this exogenous shock, we mitigate the omitted variables problem, a common limitation in existing subway capitalization studies. We estimate the incremental effect of subway capitalization, and infer a 1.8 to 2.7 percentage point increase in people's willingness to pay for subway proximity, which is roughly 36% to 60% of the initial price premium for subway proximity. This increase is mainly due to the change in transportation mode following the driving restriction policy. We also find that the increase in demand for subway proximity exhibits significant spatial heterogeneity. Locations where subway travel time can better match that of car travel experience relatively higher housing price appreciation. Moreover, we find evidence that the increase in subway premium persists over time. Our estimation provides a basis for a sound cost–benefit analysis regarding how much and where the government should increase the supply of subway services after imposing restrictions on private driving.
•This paper studies to what extent subway demand increased after Beijing imposed restrictions on private driving in October, 2008.•Utilizing a pseudo-repeat sale approach, we mitigate the omitted variables problem in the hedonic method.•We estimate a 1.8 to 2.7 percentage point increase in people' s willingness to pay for subway proximity.•Locations where subway travel time can better match that of car experience relatively higher housing price appreciation.
In this paper, transportation problem of hazardous materials (hazmat) by various transportation modes is considered. Accident probabilities related to human and ecologic risks are assumed for each ...transportation mode including road, rail, and marine modes. Thus, a two-stage approach following the fault tree analysis (FTA) first, a mathematical modeling approach second is provided. In the first stage, FTA is employed to analyze the risks for each transportation mode. In the second stage, a mixed integer nonlinear programing model is formulated by using the results of the FTA to minimize the transportation cost and risk cost for each mode. Computational results for the instances in the literature and generated instances are provided. Results show that the two-stage approach is able to produce high-quality solutions. Most effective parameter is human-based possibility with 82% for the road accident, vehicle-based possibility with 64% for the rail accident, material-based possibility with 76% for the marine accident during the hazmat transportation.
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