Monash University, Institute of Transport Studies: World Transit Research (WTR)
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A survey of Flex-Route Transit problem and its link with Vehicle Routing Problem
No full textFlexible transport systems such as Demand Responsive Transit (DRT) are becoming more and more popular over the last few years due to their convenience for customers. However, this convenience comes at a price. Transport authorities are currently looking for ways to improve service flexibility of Conventional Public Transport (CPT), which is undoubtedly cheaper than DRT. This justifies the need for Flex-Route Transit (FRT), which combines the flexibility of DRT and the low cost of CPT. This paper surveys research developments on FRT, as a promising alternative mode of public transport. Based on this survey, we discuss current research gaps that may be filled to increase FRT applicability. Moreover, we show how literature on classic Operations Research problems is of help to do so. In particular, we study similarities and differences between FRT and Vehicle Routing Problem, and specifically with one of its variant named Dial-a-Ride Problem. The analysis illustrates promising techniques that may be of use for solving FRT
Analysis and estimation of energy consumption of electric buses using real-world data
No full textWith the increasing popularity of electric buses (EBs), accurate estimation of the trip-level energy consumption of EBs has become increasingly essential. In this paper, an effective energy consumption estimation approach was proposed based on real-world operation data of EBs. Operation data of EBs from 3 different bus routes were collected and pre-processed to extract energy consumption-related features from various aspects such as traffic condition, environment, vehicle status and driving behaviour. The analyses of feature distribution, feature interaction and feature importance were then carried out. And the contributions of features to energy consumption were thoroughly analysed by Shapley value. Finally, different machine learning models were built and compared. The optimal results achieved an MAPE of 4.404% under 10-fold cross-validation, with an improvement of at least 29% over existing studies on the subject
Real-time railway traffic management under moving-block signalling: A literature review and research agenda
No full textRailway traffic management is responsible for the detection and resolution of conflicts in case of disturbed operations. To minimise delay propagation, rescheduling decisions are taken by human dispatchers, possibly supported by mathematical models. Existing conflict detection and resolution (CDR) models mostly refer to conventional fixed-block multi-aspect signalling systems, in which minimum train headways are determined based on a preset number of blocks considering worst-case braking distances and number of signal aspects. In moving-block signalling systems, minimum headways are based on absolute braking distances. This paper reviews literature on CDR with the aim to identify gaps and to propose next steps in the research on CDR under moving-block signalling. A research agenda presents various modelling options, for which modelling approaches are proposed based on a comparative analysis
Passenger-oriented rolling stock scheduling in the metro system with multiple depots: Network flow based approaches
No full textThis study investigates a rolling stock scheduling problem on a metro line with multiple depots. Two novel optimization models, i.e., an arc-based and a path-based network-flow models, are formulated with the aim of improving the service level and reducing the operation cost simultaneously, in which the flexible train composition mode is also taken into consideration to well match the transport capacity and time-varying passenger demand. To solve the proposed models, a branch-and-price (B&P) approach is designed to find the near optimal operation schemes, in which the column generation is used to solve the relaxed problem at each node of the searching tree, where a dynamic programming approach is embedded to solve the pricing sub-problem associated with each depot to generate promising paths (columns) for each rolling stock unit, and then the branch-and-bound (B&B) procedure is incorporated to find integral solutions. To test the performance of the proposed approaches, a series of numerical experiments are conducted both on small-scale and real-life cases of the Beijing metro Batong line with historically recorded passenger data. The computation results have verified the improved operational efficiency and a better service level of the solutions found by our proposed approaches
What makes public transit demand management programmes successful? A systematic review of ex-post evidence
No full textTransit crowding results in negative experiences and mode change for transit riders and operational challenges for operators. The COVID-19 pandemic initiated an ongoing transformation of how, when, and where people travel, yet the challenge of balancing demand and supply in transportation remained topical. The pandemic has also exposed the traditional approach of infrastructure expansion for being too slow to respond to the challenges of crowding in a timely manner. As such, this paper provides a systematic literature review of the ex-post studies that evaluated the impact of transit demand management strategies. The paper synthesises the findings from 13 different programmes analysed in 20 studies. It is concluded that at least within the scope of the limited number of identified ex-post studies, the practice of alternative work schedules that allow employees greater freedom when to travel is the demand management approach that can bring the most significant crowding reduction. Once that flexibility is expanded, other strategies that appeal to riders’ preferences might have a larger effect as well. The findings of this review aim to encourage transit agencies to develop collaborations with large employers that can introduce alternative work schedules
A hybrid methodology for the prediction of subway train-induced building vibrations based on the ground surface response
No full textThe numerical simulation and theoretical methods for the subway train-induced vibration of the shallow foundation buildings often suffer from high cost, unstable prediction accuracy, and lack of clarity of important parameters. Therefore, a hybrid prediction method based on the Z-vibration level at the ground surface was proposed to rapidly obtain the vibration characteristics of the shallow foundation building adjacent to the subway. The numerical simulation was first used to obtain the subway train-induced vibration of the shallow foundation building under different working conditions. Then, a hybrid model was established and retrained by combining the field measurement data of the soil and building vibration along the subway line. Finally, the prediction accuracy of the hybrid model with different numbers of measurement points as input layers was explored, and a case study was performed. The results show that the most noticeable effect on subway train-induced building vibration is the length of the building span among the shallow foundation building parameters. Three measurement points of the Z-vibration level at the ground surface are suggested as the training set data for the input layer of the hybrid model in consideration of computational efficiency and accuracy. The prediction accuracy of the hybrid model gradually increases as the number of data sets increases, and the fully trained hybrid model performs more stable across the frequency range compared to the traditional model, with the majority of its predictions in the 90% confidence interval, which provides the possibility of simplifying the analysis and fast prediction of subway train-induced building vibration
A joint analysis of accessibility and household trip frequencies by travel mode
No full textThis paper examines the endogenous relationship between residential level of accessibility and household trip frequencies to tease out the direct and indirect effects of observed behavioural differences. We estimate a multivariate ordered probit model system, which allows dependence in both observed and unobserved factors, using data from the 2016 Transportation Tomorrow Survey (TTS), a household travel survey in the Greater Golden Horseshoe Area (GGH) in Toronto. The modelling framework is used to analyse the influence of exogenous variables on eight outcome variables of accessibility levels and trip frequencies by four modes (auto, transit, bicycle and walk), and to explore the nature of the relationships between them. The results confirm our hypothesis that not only does a strong correlation exist between the residential level of accessibility and household trip frequency, but there are also direct effects to be observed. The complementarity effect between auto accessibility and transit trips, and the substitution effect observed between transit accessibility and auto trips highlight the residential neighbourhood dissonance of transit riders. It shows that locations with better transit service are not necessarily locations where people who make more transit trips reside. Essentially, both jointness (due to error correlations) as well as directional effects observed between accessibility and trip frequencies of multiple modes offer strong support for the notion that accessibility and trip frequency by mode constitute a bundled choice and need to be considered as such
Assessing modal tradeoffs and associated built environment characteristics using a cost-distance framework
No full textThe relationship between the built environment and transportation mode choice is well-studied, but less attention has been spent on the way that urban environments influence the relative travel costs for different modes. This paper uses a ‘cost-distance’ framework to assess the tradeoffs between transportation modes for commuters in the Dublin metropolitan area and employs random forest models to investigate non-linearities in the relationships between relative mobility by mode and built environment characteristics. The results suggest that more ‘walkable’ built environments increase the efficiency of active transport modes; however, we also find that these environments are negatively related to cost efficiency for public transport, likely due to congestion effects for buses. Beyond these theoretical insights, the results also provide a spatially targeted set of priorities for policymakers looking to improve the efficiency of sustainable transportation modes. These methods could be applied to any global region with access to the requisite data
Exploring the association between multi-mode transport and the built environment: A comparative study of metro, bus, taxi, and shared bike use
No full textUrban transportation plays a pivotal role in sustainable city planning, with multiple transportation modes coexisting to achieve sustainable goals. Despite the extensive use of various mobility datasets to analyze mobility behaviors, comparative studies focusing on multiple transportation modes for origin-destination (OD) trips remain scarce. This study, conducted in Shenzhen, presents three in-depth comparative analyses: (1) variations in the utilization of metros, buses, taxis, and shared bikes; (2) the clustering patterns of OD flows across different modes; and (3) the influence of the built environment at origins and destinations on OD flows. The findings reveal that the use of public transportation and taxis mirrors the city\u27s polycentric layout, with each transportation mode fulfilling distinct roles in linking disparate urban areas. The nonlinear effect of the built environment on OD flows exhibits mode-specific variations, particularly in relation to thresholds. Additionally, network topology characteristics are identified as significant factors in explaining OD flows for all modes. Despite observed differences in weekday and weekend OD flow clustering, the built environment consistently correlates with daily OD flows. These findings provide valuable insights to inform mode-specific strategies that enhance sustainable urban development
The 30-min city and latent walking from mode shifts
No full textGreater public transport use may occur through meeting average travel times of 30 min or less, termed the “30-min city”. The quantification of public transport-related physical activity associated with the 30-min city is under-researched but needed to support policy interventions. In this study, latent walking steps associated with modal shifts from car use to public transport/walking are investigated using a synthetic population and trip planning tool in Sydney, Australia. Areas were identified where the largest opportunities for public and active transport investments could be made in terms of density of car commuters and potential physical activity. Analysis of socio-economics with mean potential steps and with mean travel times were also conducted. Mode shifts to public transport/walking that are within 30 min one-way commute time were associated with a mean of 1732 daily potential steps per car commuter. However, 57 % of car commuters do not have a potential public transport/walking alternative that can be made within 30 min, which supports the need to reorganise jobs and housing and/or invest in faster public transport modes. A focus should be on delivering interventions in areas with excessive commuting times. Interactive visualisations are presented to aid policymakers to encourage mode shifts to public transport/walking