Optimization of ship traffic at berthing areas of maritime container terminals via Simulation Experiment

Maritime transportation plays a leading role in the movement and minimization of transportation costs of goods between regions. One of the major challenges faced by port managers/operators is the growing number of containers or ship traffic which can affect the port container terminal productivity. Mathematical and simulation based models for berth assignments can help to solve such logistic problems in container terminals. However, existing simulation approaches are computationally intensive for optimizing the relevant factors that may affect the berth operation or port productivity. In this study, we propose a computationally efficient approach of combining simulation with Design of Experiments (DOE) to optimize the container port productivity. Further, based on a case study of container port terminal in Malaysia, we systematically examine the effect of tug pilots, berths numbers, cranes numbers and type of queue on port container terminal productivity. We found that only berth numbers, crane numbers and type of queue had significant effect on port productivity. It is recommended to adopt low container value, first serve queuing approach for serving the ships. We could achieve a maximum productivity of around 86% through our optimization model. Further, an increase of about 22% in port productivity as compared to the existing port productivity of the terminal was observed through our method

Evaluating passenger dispersal in metro train carriages through a pedestrian crowd modelling simulation

Increased patronage of suburban metro rail in many cities of the world has effected network performance. Crowding, especially during peak travel times detrimentally effects dwell times thus reducing network capacity. The authors' suggest that station dwell times are a significant factor in service punctuality and are determined by a number of variable factors such as passenger movement through doors, crowding on board, and the carrying of objects, and that these relate directly to the design of the carriage. Poor passenger dispersal within the carriage is a major factor in doorway occlusion and therefore delayed boarding and alighting. In this study, the efficacy of an experimental interior design of carriage was compared with an existing carriage interior for the Melbourne network. For that, a pedestrian crowd modelling simulation tool was used to evaluate the passenger dispersal and egress time. Results showed that with the adjustment of the structural feature within the carriage, an increase in the efficiency of egress by around 13% could be achieved. This is a significant improvement which can enhance the punctuality of the service as well as the performance of the networ

Congestion pricing with distance tolls: A review and new developments

This paper discusses the optimal toll design problem of cordon-based pricing with nonlinear distance tolls. In the previous studies, however, the cordon-based congestion pricing scheme usually takes the area-based pricing scheme or a flat toll charge method, which are not equitable and efficient. Thus, distance tolls are recently proposed by the researchers to be the new generation of cordon-based pricing. An in-depth review is first provided on the state-of-arts of the addressed topic. Then, using the similar bi-level formulation framework, some formulations are first provided in the context of stochastic user equilibrium, including four different formulations for the stochastic social optimum

An investigation of the environmental sustainability of palm biomass supply chains via dynamic simulation modeling: A case of Malaysia

With the ever-increasing need for clean and accessible energy sources, biomass has long been considered as a potential prospect. Malaysia is one of the leading suppliers and has the largest palm oil plantation in the world. Therefore, biomass from the palm oil industry appears to be a very promising alternative source of raw materials, including for renewable energy, in Malaysia. However, ensuring the environmental sustainability of the biomass supply chain (BSC) is one of the major challenges faced by the biomass industry. Therefore, this paper aims to assess the effect of changing the efficiency of transportation technology (TT) and production technology (PT) on the environmental sustainability of the palm oil BSC. We developed a dynamic simulation model to explore the greenhouse gas (GHG) emissions for 50 years (2000e2050) for three palm biomass suppliers (Johor, Perak and Pahang) in Malaysia. Results show that supplier in Perak produced the highest rate of GHG emissions in the whole system. Also, suppliers in Johor and Perak had the highest GHG emissions with 180e240 million tonnes (mt) CO2 equivalent (CO2e) and 375e400mt CO2e, respectively, from transportation of empty fruit bunches (EFB) product. In terms of production, the supplier in Perak had the highest (and constant value) of GHG emissions (up to 160 mt CO2e). The analysis shows that the supplier in Pahang generated the lowest level of GHG emissions. Our findings suggest that improvement of the transportation and production efficiency of BSC should be the priority to work towards the sustainable development of the palm biomass industry

Empirical investigation on safety constraints of merging pedestrian crowd through macroscopic and microscopic analysis

A recent crowd stampede during a New Year's Eve celebration in Shanghai, China resulted in 36 fatalities and over 49 serious injuries. Many of such tragic crowd accidents around the world resulted from complex multi-direction crowd movement such as merging behavior. Although there are a few studies on merging crowd behavior, none of them have conducted a systematic analysis considering the impact of both merging angle and flow direction towards the safety of pedestrian crowd movement. In this study, a series of controlled laboratory experiments were conducted to examine the safety constraints of merging pedestrian crowd movements considering merging angle (60°, 90° and 180°) and flow direction under slow running and blocked vision condition. Then, macroscopic and microscopic properties of crowd dynamics are obtained and visualized through the analysis of pedestrian crowd trajectory data derived from video footage. It was found that merging angle had a significant influence on the fluctuations of pedestrian flows, which is important in a critical situation such as emergency evacuation. As the merging angle increased, mean velocity and mean flow at the measuring region in the exit corridors decreased, while mean density increased. A similar trend was observed for the number of weaving and overtaking conflicts, which resulted in the increase of mean headway. Further, flow direction had a significant impact on the outflow of the individuals while blocked vision had an influence on pedestrian crowd interactions and merging process. Finally, this paper discusses safety assessments on crowd merging behaviors along with some recommendations for future research. Findings from this study can assist in the development and validation of pedestrian crowd simulation models as well as organization and control of crowd events