Nam Seok Kim

Trade-off between carbon dioxide emissions and logistics costs based on multiobjective optimization

This paper examines the relationship between the freight transport costs and the carbon dioxide (CO2) emissions in given intermodal and truck-only freight networks. When the trade-off, which is represented as the relationship, is changed, the freight mode share and route choice are also modified. To show the ever changing trade-off and mode and route choice, a decision-support tool was developed. The given intermodal freight networks represent different freight combinations (i.e., a truck-only system, a rail-based intermodal system, and a short sea-based intermodal system). Because CO2 constraints in logistics markets will need to be realized in the near future, a modal shift in freight transportation could be expected to reduce the CO2 emissions within the reasonable cost and time constraints. The technique of multiobjective optimization is used as the core of the decision-support tool for clarifying the relationship. The tool that was developed is applied to a simplified freight transport network connecting two large European ports: the Port of Rotterdam (the Netherlands) and the Port of Gdansk (Poland). The initial solution, based on the minimization of freight costs, shows that the mode share of freight is local and regional freight transportation situations, whereas the other solutions balanced with CO2 emissions show that the mode share is changed into an intermodal freight system, which is based on a hub-and-spoke network. In considering the changing demands and capacities of freight systems, five scenarios are tested to examine the impact of mode and route change on the trade-off. The results of scenario analyses show that the trade-off is significantly influenced by the demands and capacities of systems.

Assessment of CO2 emissions for truck-only and rail-based intermodal freight systems in Europe

Abstract Rail-based intermodal freight transportation systems in the European Union have been regarded as being more environmental friendly than truck-only freight systems, particularly for long-distance haulage and in terms of CO2 emissions. However, to date there has been no clear comparison of CO2 emissions between different freight systems. Therefore, this paper examines whether the intermodal freight system really does emit less CO2 than their road-based counterparts. A research framework is established in which the methods and data of earlier studies are assessed. Based on a conceptualisation of intermodal and truck-only systems, the semi-life cycle assessment technique, which excludes emissions from infrastructure and vehicle manufacturing and includes emissions from the production of fuel and direct emissions, is used in order to examine the short- and medium-term environmental impact of different freight systems. The main conclusion is that in general rail-based intermodal freight systems emit less CO2 than truck-only systems, regardless of the type of locomotive. For electric locomotives, the electricity power-generating source is the definitive factor in deciding which type of train in an intermodal freight system offers the most environmental friendly alternative: if power plants use only coal or oil fuel sources, intermodal systems using electric trains could emit more CO2 than their competitors.

Estimating trade-off among logistics cost, CO2 and time: A case study of container transportation systems in Korea

One of the basic necessary conditions for successful implementation of policies which encourage the use of intermodal freight transportation systems is to understand “what the desired mode share of the intermodal freight transportation systems is” and also “what the trade-off relationships among various concerns such as logistics cost, time and CO2 emissions are”. The objective of this study is to estimate the trade-off relationships among logistics cost, time and CO2 emissions of the freight transportation systems of Korea. For this, container cargo data, the road network for trucks and the railway network are used as a case study. The relationships are estimated by assigning container cargoes between production zones and consumption zones and by solving linear-programming-based transportation problems. This study clearly shows the trade-off relationships between attributes. The desired levels of modal split of the railway-based intermodal freight transportation system with respect to different aspects are identified. It is considered that the findings of this study would be valuable as anchor points for setting national policy directions on freight transportation system development and determining the level of subsidies for shippers or carriers who shift from trucking to a railway-based intermodal freight transportation system.

Toward a Better Methodology for Assessing CO2 Emissions for Intermodal and Truck-only Freight Systems: A European Case Study

ABSTRACT This study aims to examine whether the intermodal freight system emits less CO2 than its road-based counterpart. Three types of freight systems are considered: a truck-only system, a rail-based intermodal freight system, and a vessel-based intermodal system. Furthermore, nine scenarios are designed in terms of four different power sources for an electrified rail-based intermodal system and three different sized ships for a vessel-based intermodal system. The results show intermodal systems generally emit less CO2 than the truck-only system. However, intermodal systems can emit more CO2 than truck-only systems under certain extreme conditions of electricity production, vessel size and detour factors.

A knowledge based freight management decision support system incorporating economies of scale: multimodal minimum cost flow optimization approach

This study developed a framework incorporating economies of scale into the multimodal minimum cost flow problem. To properly account for the economies of scale observed in practice, we explicitly modelled economies of scale on quantity, distance and vehicle size in a given multimodal freight network. The proposed multimodal minimum cost flow problem formulation has concave equations due to economies of scale for quantity, non-linear equations due to economies of scale for both quantity and distance, and non-continuous equations due to the economies of scale for vehicle size. A genetic algorithm was applied to find acceptable route, mode, and vehicle size choices for the multimodal minimum cost flow problem. We demonstrated how the economies of scale influenced system (mode), route choices, and total cost under various demand/service capacity scenarios. Our results will lead into more realistic assessments of intermodal system by explicitly considering the three types of economies of scale.

Deep-sea container carrier performance: how efficient are the respective container carriers?

The central research question in this article is: how efficient are globally operating deep-sea container carriers compared with each other? The answer is that most deep-sea container carriers are quite efficient. A point efficiency analysis shows that, first, the differences between the respective container carriers are considerable, and secondly, that efficiency depends on the carriers’ strategy if performance in terms of a certain indicator is ‘good’ or ‘aimed for’. From the input-oriented data envelopment analysis (DEA) under constant returns to scale (CRS) it follows that most carriers are efficient or close to being efficient. Actually, this range of efficiency for deep-sea container carriers in such a volatile business environment is a good performance, and indicates that the carriers are successful in dealing with the Cob-Webb theorem. The input-oriented DEA [under variable returns to scale (VRS)] also shows that most carriers are efficient. The output-oriented analysis [under both CRS and VRS] again indicates that most deep-sea container carriers are efficient.