Simulation-based vulnerability assessment in transit systems with cascade failures

2021 ◽  
Vol 295 ◽  
pp. 126441
Author(s):  
Hongyu Chen ◽  
Limao Zhang ◽  
Qiong Liu ◽  
Hongtao Wang ◽  
Xiaosong Dai
2010 ◽  
Vol 13 (3) ◽  
pp. 79-100 ◽  
Author(s):  
Eirini Veliou ◽  
Konstantinos Kepaptsoglou ◽  
Matthew Karlaftis

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Bowen Hou ◽  
Shuzhi Zhao ◽  
Huasheng Liu ◽  
Jin Li

Traditional transit systems are susceptible to unexpected costs and delays due to unforeseen events, such as vehicle breakdowns. The randomness of these events gives the appearance of an imbalance in the number of operating vehicles and of unreliable transit services. Therefore, this paper proposes the queueing theory as a means to characterize the state of any given transit system considering the risk of vehicle breakdowns. In addition, the proposed method is used to create an optimized model for reserve fleet sizes in transit systems, in order to ensure the reliability of the transit system and minimize the total cost of any transit system exposed to the risks of vehicle breakdowns. The optimization is conducted based on the two main characteristics of all bus systems, namely, operator costs and user costs, in both normal and disruptive situations. In addition, the situations in our optimization are generated in scenarios that have a certain degree of probability of experiencing delays. This paper formulates such an optimization model, presents the formulation solution method, and proves the validity of the proposed method.


2019 ◽  
Vol 31 (4) ◽  
pp. 387-395
Author(s):  
Nikola Marković ◽  
Myungseob (Edward) Kim ◽  
Eungcheol Kim ◽  
Sanjin Milinković

This paper considers vehicle dispatching for a flexible transit system providing doorstep services from a terminal. The problem is tackled with an easy-to-implement threshold policy, where an available vehicle is dispatched when the number of boarded passengers reaches or exceeds a certain threshold. A simulation-based approach is applied to find the threshold that minimizes the expected system-wide cost. Results show that the optimal threshold is a function of demand, which is commonly stochastic and time-varying. Consequently, the dispatching threshold should be adjusted for different times of the day. In addition, the simulation-based approach is used to simultaneously adjust dispatching threshold and fleet size. The proposed approach is the first work to analyse threshold dispatching policy. It could be used to help improve efficiency of flexible transit systems, and thereby make this sustainable travel mode more economical and appealing to users.


1987 ◽  
Vol 113 (2) ◽  
pp. 168-177 ◽  
Author(s):  
Mark Abkowitz ◽  
Robert Josef ◽  
John Tozzi ◽  
Mary K. Driscoll
Keyword(s):  

Author(s):  
Stephanie Pollack ◽  
Anna Gartsman ◽  
Timothy Reardon ◽  
Meghna Hari

The American Public Transportation Association's use of a “land use multiplier” as part of its methodology for calculating greenhouse gas reduction from transit has increased interest in methodologies that quantify the impact of transit systems on land use and vehicle miles traveled. Such transit leverage, however, is frequently evaluated for urbanized areas, although transit systems serve only a small proportion of those areas. If transit leverage is stronger in areas closer to transit stations, studies based on larger geographies may underestimate land use and travel behavior effects in transit-served areas. A geographic information system–based data set was developed to understand better the leverage effects associated with the mature and extensive Massachusetts Bay Transportation Authority transit system in areas proximate to its stations throughout Metropolitan Boston. The region was divided into the subregion that was transit-proximate (within a half mile of a rapid transit station or key bus route), the portion that was commuter rail–proximate, and the remaining 93.3% of the region that was not proximate to high-frequency transit. Households in the transit-proximate subregion were significantly more likely to commute by transit (and walking or biking), less likely to own a car, and drove fewer miles than households in the non-transit-served areas of the region. Commuter rail–proximate areas, although denser than the region as a whole, exhibited more driving and car ownership than regional averages. Given these spatial and modal variations, future efforts to understand transit leverage should separately evaluate land use and travel effects by mode and proximity to transit stations.


Author(s):  
Vania Ceccato ◽  
Anastasia Loukaitou-Sideris

AbstractEvaluating patterns of sexual violence against young people across the world in the era of the #MeToo movement presents great opportunities for research and practice but also challenges. The aim of this article is to critically assess an internet-based methodology employed in a comparative study conducted with university students in 18 different cities, in six continents. While our main purpose is to examine the methodological aspects of this study, the article also presents briefly its major findings and discusses compiled recommendations to curb sexual violence in some of the most important transit systems in the world. Findings show that sexual violence in transit environments is a common occurrence globally, is highly underreported, and ranges considerably from one city to the other, and between gender groups. Lessons from this study suggest that it is crucial to use identical research tools and choose partners who can ensure that research tasks are undertaken on time, ethically, and with good care for the quality of data and the research process. To curb sexual violence on transit, actions tailored to local contexts are necessary, but as underreporting of harassment is prevalent in all contexts, one global need is initiatives that facilitate incident reporting.


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