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Yung-Cheng Lai

Bio: Yung-Cheng Lai is an academic researcher from National Taiwan University. The author has contributed to research in topics: Train & Track (rail transport). The author has an hindex of 16, co-authored 44 publications receiving 656 citations. Previous affiliations of Yung-Cheng Lai include University of Illinois at Urbana–Champaign.

Papers
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Journal ArticleDOI
TL;DR: In this article, train dispatching simulation software was used to analyze the effect of various combinations of intermodal, unit, manifest, and passenger trains on a hypothetical, signalized, single-track line with characteristics typical of a North American railroad subdivision.
Abstract: North American railroads are experiencing rapid growth in traffic demand and increasingly need to expand capacity to accommodate it. Efficient planning of new capacity requires understanding how the mixture of traffic interacts to affect capacity. Different train types can have substantially different operating characteristics, including maximum speed, power-to-ton ratio, and dispatching priority. Heterogeneity in the mix of characteristics of different train types creates greater delays than are created if traffic is homogeneous. Train dispatching simulation software was used to analyze the effect of various combinations of intermodal, unit, manifest, and passenger trains on a hypothetical, signalized, single-track line with characteristics typical of a North American railroad subdivision. Analyses included the influence on delay by various traffic and train characteristics. As has been shown by previous investigators, heterogeneity increases delay, but different types of heterogeneity had differing effects, which has implications for capacity planning. This paper attempts to provide a better understanding of the impacts of various aspects of train type heterogeneity to enable more effective planning and efficient rail operations. The results also suggest certain operating strategies that may reduce the delays caused by train type heterogeneity.

85 citations

Journal ArticleDOI
TL;DR: In this article, an enhanced parametric capacity evaluation tool has been developed to assist railroad companies in capacity expansion projects, based on the Canadian National Railway Company parametric model by incorporating enumeration, cost estimation, and impact analysis modules.
Abstract: Many railroad lines are approaching the limits of practical capacity, and estimated future demand is projected to increase 84% by 2035. Therefore, identifying a good multiyear capacity expansion plan has become a particularly timely and important objective for railroads. An enhanced parametric capacity evaluation tool has been developed to assist railroad companies in capacity expansion projects. This evaluation tool is built on the Canadian National Railway Company parametric model by incorporating enumeration, cost estimation, and impact analysis modules. Based on the subdivision characteristics, estimated future demand, and available budget, the proposed tool will automatically generate possible expansion alternatives, compute line capacity and investment costs, and evaluate their impact. For a particular subdivision, there are two outputs from this decision support tool: a plot that depicts the delay-volume relationship for each alternative and an impact and benefit table that shows the impact of the ...

63 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed an aerodynamic loading assignment model for intermodal freight trains based on an integer-programming framework to help terminal managers make up more fuel-efficient trains.
Abstract: We develop an aerodynamic loading assignment model for intermodal freight trains based on an integer-programming framework to help terminal managers make up more fuel-efficient trains. This is the first use of optimization modeling to address the aerodynamics and energy efficiency of railroad intermodal trains. Several recommendations regarding railway equipment use, operations, and policy are proposed to improve fuel-efficiency and reduce emissions from intermodal transportation. Analysis of one major railroad intermodal route reveals the potential to reduce fuel consumption by 15 million gallons per year with corresponding savings of $28,000,000. Greater benefits are possible through broader implementation of the model.

58 citations

Journal ArticleDOI
TL;DR: A network optimization model that selects cost-effective installation sites for wayside defect detection system over a railroad network that can be solved efficiently and has the capability of being applied to full-scale railroad networks at either regional or national levels is presented.
Abstract: Railroads have been using wayside inspec- tion technologies for many years to improve the safety and efficiency of operations. There has been a recent proliferation of new, more sophisticated, but also more costly inspection systems that are capable of detecting a wide range of subtle defects before a problem has actually occurred. This new class of "predictive" wayside detec- tion systems, as compared with the older "reactive" tech- nologies, requires a different deployment strategy. The higher cost of these new technologies means that it is par- ticularly important for railroads to maximize the benefit they derive from the investment. This article presents a network optimization model that selects cost-effective in- stallation sites for wayside defect detection systems over a railroad network. The objective is to maximize the total inspection benefits possible under any given investment budget. We develop solution techniques based on La- grangian relaxation to effectively solve the problem. The article also presents case studies with empirical data to illustrate the technique. The computational results show that the problem can be solved efficiently, and that the model has the capability of being applied to full-scale railroad networks at regional or national levels. There are a variety of ways that railroads can use this model to help them more efficiently invest in wayside inspection

47 citations

Journal ArticleDOI
TL;DR: In this paper, a decision support framework with three stand-alone tools for strategic railway capacity planning is presented, namely, Alternatives Generator, Investment Selection Model, and Impact Analysis Module, which evaluate the trade-off between capital investment and delay cost.
Abstract: The potential growth of railway traffic is expected to be substantial worldwide; hence, railway companies and agencies are looking for better tools to allocate their capital investments to capacity planning in the best possible way. This paper presents a comprehensive decision support framework with three stand-alone tools for strategic railway capacity planning: (1) “Alternatives Generator,” which enumerates the possible expansion options along with their cost and capacity effects; (2) “Investment Selection Model,” which determines the portions of the network that need to be upgraded with certain capacity improvement alternatives; and (3) “Impact Analysis Module,” which evaluates the trade-off between capital investment and delay cost. This research also developed and implemented a specific decision support framework for North American class 1 railroads. On the basis of the network characteristics, estimated future demand, and available budget, this decision support framework can successfully determine t...

47 citations


Cited by
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Book
01 Jan 1988
TL;DR: In this paper, the evolution of the Toyota production system is discussed, starting from need, further development, Genealogy of the production system, and the true intention of the Ford system.
Abstract: * Starting from Need* Evolution of the Toyota Production System* Further Development* Genealogy of the Toyota Production System* The True Intention of the Ford System* Surviving the Low-Growth Period

1,793 citations

Posted Content
TL;DR: From smart grids to disaster management, high impact problems where existing gaps can be filled by ML are identified, in collaboration with other fields, to join the global effort against climate change.
Abstract: Climate change is one of the greatest challenges facing humanity, and we, as machine learning experts, may wonder how we can help. Here we describe how machine learning can be a powerful tool in reducing greenhouse gas emissions and helping society adapt to a changing climate. From smart grids to disaster management, we identify high impact problems where existing gaps can be filled by machine learning, in collaboration with other fields. Our recommendations encompass exciting research questions as well as promising business opportunities. We call on the machine learning community to join the global effort against climate change.

441 citations

Journal ArticleDOI
TL;DR: The academic literature on urban policy and planning which explicitly links to Neo-liberalism is huge as mentioned in this paper, with an emphasis on journals of urban planning, urban geography, and urban studies.

378 citations

Journal ArticleDOI
TL;DR: It is convenient to develop reasoning in analytical terms and for simplicity to restrict the flow to two dimensions and the engineer will find special scope in this part of aerodynamics for graphical methods in the solution of particular problems.
Abstract: WE found, on experimental grounds in Article I, that the field of air‐flow past a short body of low resistance shape, such as an aerofoil, comprises two dissimilar parts: (a) a thin boundary layer enveloping the body and dominated by viscous effects, and (b) a motion outside the boundary layer in which viscosity is much less important. It will be remembered that in the external motion occur the large pressure changes, which, transmitted through the boundary layer, account for nearly all the lift and for part of the drag. These pressures we observed to be calculable from the velocities without appreciable error by Bernoulli's equation. In the present Article we confine attention to this external flow, assuming it to be steady, incompressible, and inviscid. Its dependence upon (a), already discussed to some extent, we ignore; the boundary layer is conceived to be everywhere very thin, so that the only role it plays is to allow of relative velocity at the surface of the body. The assumptions made, excepting that of incompressibility, will appear drastic, and it will not be surprising if some of our deductions prove discordant with experimental fact. Nevertheless, they lead to a theory which finds many applications and uses in real fluid motion, and, in particular, gives an intimate view of aerofoil flow that is very close to the truth. It is convenient to develop our reasoning in analytical terms and for simplicity to restrict the flow to two dimensions (Article 1, §5). But the engineer will find special scope in this part of aerodynamics for graphical methods in the solution of particular problems.

373 citations

01 Jan 2008
TL;DR: In this article, the authors present applications of the Transit Capacity and Quality of Service Manual (TCQSM) methodologies to fixed-route transit systems in Mexico, focusing on the quality of service part of the manual.
Abstract: This paper presents applications of the Transit Capacity and Quality of Service Manual (TCQSM) methodologies to fixed-route transit systems in Mexico. The applications are focused on the quality of service part of the manual. The TCQSM provides a simple and clear way to analyze transit systems in other countries such as Mexico as there are no significant differences with transit systems in the US. However, several factors and thresholds such as walking distance, passenger load factors, transit supportive areas and the difference between transit and auto travel times should be further researched and adapted to local conditions since these values have a significant effect on the determination of the appropriate level-of-service (LOS). Furthermore, there are other performance measures such as on-time reliability, safety and security, and headway adherence that are not commonly reported by transit systems in Mexico and therefore, the TCQSM methodologies are not applicable. The paper describes the applications and the adjustments necessary to apply such methodologies and highlights its advantages and limitations for applications in Mexico.

295 citations