Analysis of Identification Methods of Key Nodes in Transportation Network

The identification of key nodes plays an important role in improving the robustness of the transportation network. For different types of transportation networks, the effect of the same identification method may be different. It is of practical significance to study the key nodes identification methods corresponding to various types of transportation networks. Based on the knowledge of complex networks, the metro networks and the bus networks are selected as the objects, and the key nodes are identified by the node degree identification method, the neighbor node degree identification method, the weighted k-shell degree neighborhood identification method (KSD), the degree k-shell identification method (DKS), and the degree k-shell neighborhood identification method (DKSN). Take the network efficiency and the largest connected subgraph as the effective indicators. The results show that the KSD identification method that comprehensively considers the elements has the best recognition effect and has certain practical significance.

Analysis of Spatial-Temporal Characteristics of Operations in Public Transport Networks Based on Multisource Data

Operational efficiency and stability are two critical aspects to measure bus systems. Influenced by many stochastic factors, buses always suffer from delay and bunching. Traditional studies focus on a single route and lack research on the systematic evaluation of bus network. In this paper, we propose a data-driven framework to analyze the efficiency and stability based on small granularity GPS trajectory data from the perspective of entire bus network. The IC card data and route data are used to extract the boarding passenger number and topological structure, respectively. The results show that the average headway of stations follows a lognormal distribution. Moreover, the distribution of arrival efficiency of stations is inhomogeneous and a small number of stations have large values. In addition, the relationships among average headway of stations, boarding passenger number, bus number, and complex network indicators are revealed. It is found that the average headway of station is negatively correlated with other indicators, which implies that complex network connections and more passenger flows could weaken the efficiency of bus operations. This paper provides a way to evaluate the operational performance of bus networks and could give help for monitoring and optimizing the daily operation of bus systems.

A Boost for Urban Sustainability: Optimizing Electric Transit Bus Networks in Rotterdam

In 2016, the Dutch government, in pursuit of the UN’s sustainable development goals, set a target that all its diesel transit bus networks should be fully electrified between 2025 and 2030. A research team from Rotterdam School of Management has since worked in close collaboration with Rotterdamse Elektrische Tram, the public transport operator in the city of Rotterdam, to accomplish this complex transition. This paper presents essential lessons learned and key practical implications derived from the project. As part of the transition process, we developed a discrete-event simulation model that can simulate the network using different settings and under uncertainty. We also formulated a mixed-integer linear programming problem to optimize the charging schedule. To mitigate the critical impact of uncertainty regarding traffic delays and energy consumption on the electrified transit bus network operation, we developed a real-time decision support system that adjusts and reoptimizes the charging schedule during the day according to the realizations of this uncertainty. We use this system to achieve better coordination between the charging schedule of the electric buses and electricity generation from renewable energy sources with the latter involving high levels of uncertainty. Our study shows the benefits of real-time optimization compared with off-line planning and other greedy strategies. We also show that even highly conservative off-line planning might not be sufficient to maintain reliability levels under extreme operational uncertainty conditions. Additionally, our results and insights have substantially contributed to the success of the first phase of the project, which involved electrifying seven essential bus lines in the city, in realizing a robust and reliable operational plan. Finally, our study shows the potential substantial positive impact of installing renewable energy generators and coordinating the electric buses’ charging schedule with their output power profile. Based on our recommendations, RET developed a real-time monitoring system and is working on incorporating our charging schedule optimizer into its planning process.

Accurate fault detection during power swing: compensated line study

Purpose The purpose of this study is to develop an algorithm to accurately detect faults in series capacitor compensated (SCC) power transmission lines. The line fault must be distinguished from stable power swing, compensating unit malfunction and defects on other lines sharing the same bus (external faults). Design/methodology/approach In this regard, an effective fault feature extractor based on the cumulative sum (CUSUM) of the amplified second harmonic of the phase currents is suggested. The features are then applied to an artificial neural network for classification. No-fault cases include stable power swing and several disturbances. Due to the independent analysis of each phase, faulty phase detection is also a by-product. Findings Various fault scenarios are defined, and the algorithm success rate is compared with some newly published methods. Extensive simulations performed over a single-machine infinite bus, a 3-machine, 9-bus and the large-scale New England IEEE 39-Bus networks all indicate that the proposed algorithm can trip the faulty line more quickly and accurately than the contestant algorithms. Originality/value Suggestion of a new algorithm based on the CUSUM of the amplified second harmonic of the phase current for the fault feature extraction that is able to isolate the transmission line internal faults from stable poser swing, line compensating unit malfunction and faults on the adjacent lines connected to the same bus.

Cybersecurity attacks on CAN bus based vehicles: a review and open challenges

PurposeNowadays, connected vehicles are becoming quite complex systems which are made up of different devices. In such a vehicle, there are several electronic control units (ECUs) that represent basic units of computation. These ECUs communicate with each other over the Controller Area Network (CAN) bus protocol which ensures a high communication rate. Even though it is an efficient standard which provides communication for in-vehicle networks, it is prone to various cybersecurity attacks. This paper aims to present a systematic literature review (SLR) which focuses on potential attacks on CAN bus networks. Then, it surveys the solutions proposed to overcome these attacks. In addition, it investigates the validation strategies aiming to check their accuracy and correctness.Design/methodology/approachThe authors have adopted the SLR methodology to summarize existing research papers that focus on the potential attacks on CAN bus networks. In addition, they compare the selected papers by classifying them according to the adopted validation strategies. They identify also gaps in the existing literature and provide a set of open challenges that can significantly improve the existing works.FindingsThe study showed that most of the examined papers adopted the simulation as a validation strategy to imitate the system behavior and evaluate a set of performance criteria. Nevertheless, a little consideration has been given to the formal verification of the proposed systems.Originality/valueUnlike the existing surveys, this paper presents the first SLR that identifies local and remote security attacks that can compromise in-vehicle and inter-vehicle communications. Moreover, it compares the reviewed papers while focusing on the used validation strategies.

Discussion on Optimization of Public Transportation Network Setting considering Three-State Reliability

In order to be environment-friendly, relieve traffic congestion, reduce pollution, and be green and sustainable, the optimization and development of public transportation, as the subject of people's long-term research, has always been shining. With the emergence of shared transportation, public transportation systems face more challenges. In order to better connect with bike-sharing, car-sharing, and other modes of transportation, public transportation will carry out important reforms, among which the optimization of line network is one of the most important tasks. The traditional bus route design is mainly based on the “four-stage” method model, which is mainly based on the investigation and analysis of the existing traffic system and land use. Through the work flow of “evaluation, calibration, and verification,” the network balance optimization model is used to get the bus travel allocation prediction model. In this paper, the optimization problem of public transit network is studied from the point of view of the reliability of public transit network. It is proposed that public transit network can be abstracted into series-parallel system and parallel-series system model from the three states of normal, short-circuit failure, and open-circuit failure and is analyzed and discussed through the hypothesis experiment. The research of this paper will provide a new perspective for the optimization of public transit network, complement the traditional methods, and support the optimization and reliability improvement of urban public transit network. More reliable bus networks and other modes of transportation, such as walking, bike-sharing, and rail, will become more suitable for people to get around.

Using GTFS to Calculate Travel Time Savings Potential of Bus Preferential Treatments

Dedicated bus lanes and other transit priority treatments are a cost-effective way to improve transit speed and reliability. However, creating a bus lane can be a contentious process; it requires justification to the public and frequently entails competition for federal grants. In addition, more complex bus networks are likely to have unknown locations where transit priority infrastructure would provide high value to riders. This analysis presents a methodology for estimating the value of bus preferential treatments for all segments of a given bus network. It calculates the passenger-weighted travel time savings potential for each inter-stop segment based on schedule padding. The input data, ridership data, and General Transit Feed Specification (GTFS) trip-stop data are universally accessible to transit agencies. This study examines the 2018 Metropolitan Atlanta Rapid Transit Authority (MARTA) bus network and identifies a portion of route 39 on Buford Highway as an example candidate for a bus lane corridor. The results are used to evaluate the value of time savings to passengers, operating cost savings to the agency, and other benefits that would result from implementing bus lanes on Buford Highway. This study does not extend to estimating the cost of transit priority infrastructure or recommending locations based on traffic flow characteristics. However, it does provide a reproducible methodology to estimate the value of transit priority treatments, and it identifies locations with high value, all using data that are readily available to transit agencies. Conducting this analysis provides a foundation for beginning the planning process for transit priority infrastructure.

Investigating the Preferences of Local Residents toward a Proposed Bus Network Redesign in Chattanooga, Tennessee

Many transit agencies are considering or implementing bus network redesigns. Considering this growing trend, this study investigates the preferences of local residents for a proposed bus network redesign in Chattanooga, Tennessee. The study uses survey data collected by the Chattanooga Area Regional Transportation Authority and its partners as part of a bus network redesign planning process. Using the survey data, three logit models are estimated to explore preferences between different bus network redesign philosophies, transit network improvements, and willingness to pay for proposed transit improvements and expansion. There are three main findings. First, respondents who ride the bus prefer access to more places over frequent bus service, whereas non-riders prefer more frequent transit service. Second, the models suggest that younger generations are more supportive of transit improvements than older age groups. Third, people living near bus routes and those with higher income levels are more willing to pay for proposed transit improvements. The findings of this study should inform transit agencies that are considering or are in the process of redesigning their bus networks.

The place for immigrants in Toronto`s transit and transportation city

This study conducted qualitative interviews with nine immigrants on their experiences of public transit in Toronto. It synthesizes and builds on existing data that indicate that immigrants, especially women, highly depend on public transit despite settling in the peripheries of Toronto, away from subway lines and close to major highways. I identify gaps in existing academic and policy debates on transportation planning in Toronto and propose an environmental justice framework that is grounded in immigrants`experiences of navigating public transit and their spatial locations. The research findings highlight the limited affordability of public transit, the poor servicing and connectivity of bus networks, and the resulting barriers to accessing work opportunities across the region. I further analyze the role of the built environment in limiting or facilitating access for gendered activities such as grocery shopping and traveling with children. The paper concludes by highlighting the need for new directions in transit policy and planning that can better address the changing demographics and social and spatial divisions in the city.

The place for immigrants in Toronto's transit and transportation city

This study conducted qualitative interviews with nine immigrants on their experiences of public transit in Toronto. It synthesizes and builds on existing data that indicate that immigrants, especially women, highly depend on public transit despite settling in the peripheries of Toronto, away from subway lines and close to major highways. I identify gaps in existing academic and policy debates on transportation planning in Toronto and propose an environmental justice framework that is grounded in immigrants’ experiences of navigating public transit and their spatial locations. The research findings highlight the limited affordability of public transit, the poor servicing and connectivity of bus networks, and the resulting barriers to accessing work opportunities across the region. I further analyze the role of the built environment in limiting or facilitating access for gendered activities such as grocery shopping and traveling with children. The paper concludes by highlighting the need for new directions in transit policy and planning that can better address the changing demographics and social and spatial divisions in the city.