A break-even model for evaluating the cost of container ships waiting times and berth unproductive times in automated quayside operations

The planning, design and development of a container terminal with optimum size and capacity and with a minimum capital cost is fundamentally dependent upon the loading and discharging operations at the quayside. The quayside function of container terminals is dependent basically on the number of berths available to service the incoming container ships. The objective of the container terminals dealing and admitting the ongoing ship calls is to provide immediate berth and loading and discharging services to the container ships with a minimum costly waiting time and a maximum efficiency. Previously terminal planners used to build extra berths to provide service. During the last two decades the terminal operators have adopted automation technologies in loading and discharging operation of the container ships as an alternative to designing extra berths. Ship owners naturally expect least waiting times for their container ships. On the other hand, it is also natural for port operators in a container terminal with costly facilities to see a high berth occupancy and productivity at the quayside. This study uses queuing theory to find a break-even point as a way of evaluating the cost of container ship waiting times and the cost of berth unproductive service times for container terminals aiming to automate their quayside operation. The analysis illustrates that automation devices installed on conventional Quayside Cranes (QSCs) significantly reduce the turnaround time of the container ships calling at the ports. It argues, however, that there should be a balance between the cost of berth unproductive service times and the cost of vessel waiting times. The study introduces a break-even point to be considered as a benchmark for calculating such a balance. The analysis in this study can be used as a decision tool for the operators of container terminals in the medium to small ports to appraise the feasibility of an investment in automation or expansion of the quayside facilities.     

Transfer penalties: Another look at transit riders' reluctance to transfer

Two on-board surveys were conducted to determine how transit riders perceive transfers. The surveys were conducted before and after the imposition of a transfer in the middle of an existing bus route. Results of the surveys showed that riders perceive bus transit trips as significantly worse when the trip requires a transfer, even if transfer time is neglibible.     

船队运力过剩的解决方案

我想就航运界普遍担忧的运力过剩问题谈谈自己的看法. 首先来看一组数据:根据克拉克森统计,今年1～10月份全球新接订单合计9512万载重吨,同比增长162%.而截至2010年9月初,油轮、货轮和集装箱船的订单占现有船队的比例分别高达28.5%、54.5%和24.9%.今年1～9月份,中国新船订单5071万载重吨,是去年同期1692万载重吨的三倍.中国承接的新船订单占了全球订单总量的45.6%.航运市场今后如何消化这么庞大的运力?这是航运界需要审慎对待的问题.     

Quantitative assessment of effect of enforcement intensity on violation rates of vehicle weight and dimension regulations

A theory of upper bound limit describing the relationship between maximum possible violation rate as a function of the intensity of enforcement of vehicle weight and dimension regulations and indeed other transport administrative regulations is postulated. The model is an exponential function that determines the maximum violation rate for given inspection capacity. The constant of the function depends on the method of enforcement. The theory is demonstrated to be valid. It has potential for facilitating important policy issues relating to enforcement of transport administrative regulations and within the framework of infrastructure management to be addressed.

The relative effectiveness of enforcement methods is quantified by two parameters namely, the effectiveness index and the truckers’ relative perceived probability of detection. These parameters facilitate evaluation of the performance of various enforcement methods and operation strategies. It is found that patrol teams are, on average, 30 times as effective in detecting violations as continuously operated permanent weigh scales. High perceived detection probabilities are associated with high inspection capacities. To increase the perceived detection probability (reduce violation rates) therefore implies increasing the inspection capacity.     

Maritime investment strategies with a portfolio of real options

The maritime industry operates in a dynamic global environment subject to a great number of variables. In this context, the investment challenge facing shipowners is correctly to value alternate mutually exclusive investment strategies before proceeding with confidence to commit to a project which will add the greatest value to the firm. To survive in the competitive market environment shipping companies must be flexible. Companies that rely solely on traditional discounted cash flow analysis may be underestimating the true value of their investment by not valuing any embedded real options specifically. To avoid misallocation of resources, the true value of these embedded options (strategies) should be recognised and quantified where possible for inclusion in the capital budgeting process. Using real options analysis, (ROA), as a development of the financial pricing advances of the 1970s, flexibility is valued like a financial option using non-arbitrage and added to the present value of the original strategy to derive the present value of the flexible strategy. The more uncertainty (risk) present, the greater will be the value of the real options. Similarly, the larger the shipowner's portfolio of options (strategies) from which to choose, the greater will be the valuation of the project. Real options give the shipowner the flexibility to exchange one risky income stream associated with one strategy for that of another. The analysis shows that if managers have the flexibility of more than one embedded option (in this paper, a European put associated with a replacement investment and an option on the maximum of two operating strategies, trading or chartering out) then the project will have greater value than if the there was no choice or if it was limited to one or the other strategy. Sensitivity analysis extends the analysis to demonstrate that if the volatilities of the risky income streams are highly correlated then the additional value of this flexibility will diminish.     

Dynamic ride-sharing: A simulation study in metro Atlanta

Smartphone technology enables dynamic ride-sharing systems that bring together people with similar itineraries and time schedules to share rides on short-notice. This paper considers the problem of matching drivers and riders in this dynamic setting. We develop optimization-based approaches that aim at minimizing the total system-wide vehicle miles incurred by system users, and their individual travel costs. To assess the merits of our methods we present a simulation study based on 2008 travel demand data from metropolitan Atlanta. The simulation results indicate that the use of sophisticated optimization methods instead of simple greedy matching rules substantially improve the performance of ride-sharing systems. Furthermore, even with relatively low participation rates, it appears that sustainable populations of dynamic ride-sharing participants may be possible even in relatively sprawling urban areas with many employment centers.     

A numerical model of the long term flow along the Malin-Hebrides shelf

A three dimensional hydrodynamic model of the Malin-Hebrides shelf region is used to investigate the spatial variability of the wind and tidally induced residual flow in the region and the influence of flow from the Irish Sea and along the shelf edge. By this means it is possible to understand the spatial variability in the long term observed flow fields in the region and the range of driving forces producing this flow. The model uses a sigma coordinate grid in the vertical with a finer grid in the near surface and near bed shear layers. The vertical diffusion of momentum in the model is parameterised using an eddy viscosity coefficient which is derived from turbulence energy closure models. Two different turbulence models are used to compute the eddy viscosity, namely a two-equation (itq²−q²ℓ) model which has prognostic equations for both turbulence energy and mixing length and a simpler model in which the mixing length is a specified algebraic function of the water depth.The wind induced response to spatially and temporally constant orthogonal wind stresses, namely westerly and southerly winds of 1 N m⁻², are derived from the model. By using orthogonal winds and assuming linearity, then to first order the response to any wind direction can be derived. Computed flows show a uniform wind driven surface layer of magnitude about 3% of the wind speed and direction 15 ° to the right of the wind, in deep water. Currents at depth particularly in the shelf edge and near coastal region show significant spatial variability which is related to variations in bottom topography and the coastline.Calculations show that tidal residual flows are only significant in the near coastal regions where the tidal current is strong and exhibits spatial variability. Flow into the region from the Irish Sea through the North Channel although having its greatest influence in the near coastal region, does affect currents near the shelf edge region. Again the spatial variability of the flow is influenced by topographic effects.A detailed examination of wind induced current profiles together with turbulence, mixing length and viscosity, at a number of locations in the model from deep ocean to shallow near coastal, shows that both turbulence models yield comparable results, with the mixing length in the two equation model showing a similar dependence to that specified in the simpler turbulence model.Calculations clearly show that flow along the shelf edge area to the west of Ireland and from the Irish Sea entering the region, together with local wind forcing can have a major effect upon currents along the Malin-Hebrides shelf. The flow fields show significant spatial variability in the region, comparable to those deduced from long term tracer measurements. The spatial variability found in the calculations suggests that a very intense measurement programme together with inflow measurements into the area is required to understand the circulation in the region, and provide data sets suitable for a rigorous model validation.     

The Application of Roller Rigs to Railway Vehicle Dynamics

Roller rigs have been built world-wide to research into the dynamics of railway vehicles and they have particularly been applied to the development of high-speed trains. This survey takes into consideration both full scale as well as small scale model roller rigs. Besides performance, most important experimental work and the emphasis of application, the scaling strategies of model test rigs and the differences involved in roller rig experiments are treated. Suggestions for potential future uses and developments are also given for this tool which is useful for demonstration and analysis of railway vehicle dynamic behaviour.