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Wang Z.,China Sustainable Transportation Center | Koutsopoulos H.N.,KTH Royal Institute of Technology
Proceedings - Winter Simulation Conference | Year: 2011

Rail simulation model calibration is a process of adjusting model parameters while comparing model output with observations from the real rail system. There is a lack of systematic methodology for calibrating urban rail simulation models. Based on a simulator developed for urban rail operations and control, the paper demonstrates a methodology of calibrating model parameters, and specifically, fine-tuning some of the simulation inputs. The calibration process is modeled as a multi-variate optimization problem and solved by the Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm. A case study of the Massachusetts Bay Transportation Authority (MBTA) Red Line shows that the methodology improves the simulation model dramatically in terms of replicating the track block runtimes. At the same time, it upgrades the station specific dwell time parameters and enhances a-priori boarding rates at stations fairly effectively. © 2011 IEEE. Source


Wang Z.,China Sustainable Transportation Center | Li Y.,Kunming Urban Planning and Design Institute
Mitigation and Adaptation Strategies for Global Change | Year: 2015

Super block and giant road networks have been a dominant form of China’s new town development. This may lead to numerous urban problems, such as high automobile dependency, heavy traffic congestion, and unwalkable communities. In recent years, the transformation of superblocks to a new urban form with human-scale blocks and fine-grain grid road networks in certain cities in China has drawn much attention. Despite its recent positive attention, the following important questions have been raised: How will the transformation impact road network capacity? How will the changes contribute to transportation carbon emission (CE) reduction or increase? How will cities deal with rearranging the cost structure among the different stakeholders in road construction, maintenance, and management? Related factors and approaches for a solution to such issues are discussed in this study, followed by further analysis using a case study of the core area of Chenggong, a new town in Kunming, China. The study shows that concern about a negative impact on road network capacity is unfounded. Estimation using empirical data from other cities shows that a significant CE reduction is likely to be achieved; and through reasonable cost restructuring and management, a win-win situation is possible for all road construction, maintenance, and management stakeholders. Thus, an optimized societal cost-benefit arrangement can be reached through the transformation. © 2014, Springer Science+Business Media Dordrecht. Source


Jiang Y.,China Sustainable Transportation Center | Christopher Zegras P.,Massachusetts Institute of Technology | Mehndiratta S.,The World Bank
Journal of Transport Geography | Year: 2012

This paper examines BRT station walk access patterns in rapidly urbanizing China and the relationship between bus rapid transit (BRT) station context and corridor type and the distance people will walk to access the system (i.e., catchment area). We hypothesize that certain contextual built environment features and station and right-of-way configurations will increase the walk-access catchment area; that is, that urban design influences users' willingness to walk to BRT. We base our analysis on 1233 user surveys, conducted at 19 BRT stations along three existing (as of summer 2009) BRT corridors in the city of Jinan. Ordinary least squares regression is applied to estimate the relationship between walk access distances and aggregate station- and corridor-area characteristics, controlling for individual- and trip-specific attributes. The results suggest that people walk farther to BRT stations when the walking environment has certain features (median transit-way station location, shaded corridors, busy and interesting). Trip and trip maker characteristics play a relatively minor role in defining BRT walk access distance. Implications include the need for flexible transit station catchment area definitions in identifying transit-oriented development opportunities and estimating system demand. © 2011 Elsevier Ltd. Source


Wang J.,China Sustainable Transportation Center | He D.,Energy Foundation
Mitigation and Adaptation Strategies for Global Change | Year: 2015

China is undergoing rapid urbanization, along with economic growth and transport automation. Because it is densely populated, China is constrained by natural resource limitations and potential impacts of global climate change. Significant challenges for sustainable urban development include urban sprawl, traffic congestion, air pollution, city layouts not oriented to twenty-first century lifestyles, declining traditional urban culture, selective over-development, and social inequities. Increasing awareness of these pressing problems has led national and provisional governments and cities to seek sustainable urban development solutions. Central ministries and non-government organizations have implemented pilot projects demonstrating best practices in the Chinese context. These are being scaled up to develop local and national guidelines and policies. This paper describes China’s urbanization issues and national and local efforts toward the realization of sustainable urbanization. It is hoped that China’s urbanization trends and challenges will stimulate sustainable and low-carbon concepts and approaches that can enrich sustainable urbanization theory and practices in and beyond China. © 2015, Springer Science+Business Media Dordrecht. Source


Wang Z.,China Sustainable Transportation Center | Wang J.,China Sustainable Transportation Center | He D.,Energy Foundation
Transportation Research Record | Year: 2012

Promoting transit has been a national strategic policy as part of the effort to relieve traffic congestion in China. However, such promotion also offers a great potential benefit in carbon dioxide (CO2) abatement, to which insufficient attention has been paid. For the effects of transit priority policies on CO2 emissions to be understood, an evaluation and a sensitivity analysis were conducted. The relationship between public transit and CO2 emissions with respect to four contributing factors is discussed. The effectiveness of transit priority policies implemented in recent years was analyzed, and its correlation to CO2 emissions was identified. The magnitude of transit CO2 emissions from 2000 to 2008 was estimated. On the basis of varied assumptions, six scenarios were designed to analyze the sensitivity and the range of possible CO2 abatement potentials of different policies. Finally, some recommendations for future policies from the perspective of reducing CO2 are presented. Source

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