Entire Transportation Network Research Articles

Sensitivity analysis of urban air mobility aircraft design and operations including battery charging and swapping

AbstractUrban Air Mobility (UAM) is an evolving concept of passenger transportation providing on-demand flights within metropolitan environments, wherefore typically fully electric vertical take-off and landing aircraft are designed. Due to the underlying battery energy constraints, the design of UAM aircraft is very sensitive. Apart from the design considerations, the impact of aircraft operations on the entire UAM transport network must be examined. As there is no data from real-world operations available, this research article utilizes a system of systems simulation framework combining aircraft design with an agent-based simulation. The underlying approach offers the possibility of studying several parameters concerning UAM aircraft design and operations. In a case study focused on intra-city transport, aircraft design aspects regarding the payload capacity, the mission profile, and the reserve requirement are studied for a multirotor configuration. Furthermore, the aircraft operations aspects are focused on the turnaround procedures, the passenger demand, and the cruise speed. The multi-level sensitivity analysis ranging from the subsystem over the system of interest to the system of systems level allows us to trace the most sensitive aspects. Especially, the sensitivity analysis of battery fast-charging and swapping shows the importance of the holistic system of systems investigations for the successful development of UAM aircraft and services.

Bridge management systems: an overview and comparison

Bridges are one of the key elements of the transportation infrastructure of each country, and the reliability of the entire transportation network depends on their functioning. Maintaining bridges in proper technical condition is the main task of bridge management, for which more and more countries use bridge management systems (BMS). This study is devoted to comparing different BMS, reviewing the main functions and modules and determining the perspectives of development and implementation of the latest technologies in BMS. The analysed bridge management systems were compared by functions such as storage of bridge passport data, initial information on the bridge condition, assessment of the bridge condition, forecasting of the bridge condition and consideration of different maintenance strategies. Some systems are distinguished by the fact that they can predict future bridge condition, offer optimal maintenance strategies and take into account losses not only for the operation of structures, but also for transportation. Prospects for the development of BMS were also identified: the use of neural networks, the introduction of building information modelling (BIM) and the Internet of Things (IoT).

Public transport equity with the concept of time-dependent accessibility using Geostatistics methods, Lorenz curves, and Gini coefficients

The primary objective of transport policies is to improve accessibility and mitigate the adverse consequences of private vehicles. Improved accessibility can considerably contribute to urban sustainability and quality of life. To improve accessibility, measuring it as precisely as possible is very important. A greater knowledge of the accessibility levels of public transport systems would not only help in enhancing the level of service but will also aid in resource planning and budgeting (capital costs, operations & maintenance costs, etc.). The research on various accessibility methods used to investigate transportation equity, particularly public transport, revealed that most of these approaches used time-based approaches to analyze public transport accessibility under theoretical traffic conditions and accessibility to public transport corridors, but ignored the overall performance of the transportation network. In this study, we developed an accessibility measurement framework for public transport to capture the performance of the entire transport network in a multimodal fashion and applied the methodology to the City of Wuhan as a case study. The key elements are: (i) develop a multimodal transport network that captures the performance of the entire transport network at a different time of the day. (ii) adopt the utility-based accessibility method to analyze public transport accessibility to opportunities based on the attractiveness of the destination, and (iii)determine the level of the disparity of accessing job opportunities by public transport between the urban and rural areas of the city using Geostatistics methods such as Lorenz curve and Gini Coefficients. The framework adopted in this study allowed us to examine the public transport equity in the study area, and help identify the influencing factors towards enhancing transport policies that consider the fair distribution of public transport infrastructure.

Подход к расчету интенсивности транспортных потоков при организации наземных перевозок в районе ликвидации последствий чрезвычайных ситуаций по данным дистанционного зондирования Земли

When carrying out emergency recovery work to eliminate the consequences of an emergency, it is necessary to promptly provide information on the state of transport infrastructure facilities, which is possible only when using aerospace survey data. The aim of the study is to increase the efficiency of transportation in the emergency zone using heterogeneous vehicles under the conditions of synchronization of its movement, based on the use of Earth remote sensing data. Data source analysis for traffic flow modeling was carried out. Land transportation typical network graph description is presented. The dependences of the intensity of traffic flows along the edges of the network graph on traffic conditions, infrastructure characteristics and loading and unloading operations, parameters of wheeled, tracked vehicles and railway cars are revealed. It is proposed to use the minimax criterion when calculating the maximum traffic flow intensity along the network graph path and the entire transport network capacity. Based on the analysis of the tasks of monitoring the state of transport infrastructure facilities, the possibility of using Earth remote sensing data to reveal damage and flooding in the emergency zone was assessed. Based on the simulation modeling results of the ground transportation organization in the area of emergency response based on the Earth remote sens-ing data, the applicability of the proposed approach to the traffic flows intensity calculating based on the Earth remote sensing data was confirmed.

A Model Architecture for Public Transport Networks Using a Combination of a Recurrent Neural Network Encoder Library and a Attention Mechanism

This study presents a working concept of a model architecture allowing to leverage the state of an entire transport network to make estimated arrival time (ETA) and next-step location predictions. To this end, a combination of an attention mechanism with a dynamically changing recurrent neural network (RNN)-based encoder library is used. To achieve this, an attention mechanism was employed that incorporates the states of other vehicles in the network by encoding their positions using gated recurrent units (GRUs) of the individual bus line to encode their current state. By muting specific parts of the imputed information, their impact on prediction accuracy can be estimated on a subset of the available data. The results of the experimental investigation show that the full model with access to all the network data performed better in some scenarios. However, a model limited to vehicles of the same line ahead of the target was the best performing model, suggesting that the incorporation of additional data can have a negative impact on the prediction accuracy if they do not add any useful information. This could be caused by poor data quality but also by a lack of interaction between the included lines and the target line. The technical aspects of this study are challenging and resulted in a very inefficient training procedure. We highlight several areas where improvements to our presented method are required to make it a viable alternative to current methods. The findings in this study should be considered as a possible and promising avenue for further research into this novel architecture. As such, it is a stepping stone for future research to improve public transport predictions if network operators provide high-quality datasets.

Feeder Bus Reformation for an Urban Rail Project: The Case of Khon Kaen City, Thailand

The ability to use public transportation should be available throughout the whole service area and the public transportation network should be well connected. This research compared the potential coverage of a feeder bus network in support of urban rail transportation, as well as the impact of future transit network plans on public transportation accessibility in the city of Khoan Kaen, Thailand. The performance of the public transportation system was predicted based on multimodal transport and the completed urban rail public transportation plan, as projected in the year 2036, in order to fill gaps in the existing feeder bus network. The feasibility and characteristics of the route reformation policy concept should provide an effective feeder network for the urban rail system. A comparative study was conducted on stakeholder impact for a three-fold scenario: 1) separate individual lines for bus routes; 2) both forms of feeder bus networks (conventional and reformed); and 3) access to three designated utility areas from the entire feeder bus network. In this scenario, the most effective urban mobility support was provided by public facilities combined with a major roadway directly connecting to the designated positions. The time used on the extended bus route network increased by around 11% on average for the entire trip, while accessibility increased by approximately 67.75%, 47.9%, and 43.68% for the entire multimodal transport network. These analytical results make a significant contribution to future knowledge on urban transformation through urban mass transit projects. The contribution of land acquisition was significant. Also, the demand-responsive connection approach used in this study can be adopted to determine feeder bus reformation options, particularly in emerging economies.

An innovative approach to assess the impact of urban flooding: Modeling transportation system failure due to urban flooding

The transportation system is often considered a critical infrastructure as the failure of its components can have a substantial impact on the economy and social well-being of a country. Extreme weather events such as urban flooding disrupt transportation networks with delays, diversions, and partial or full closure of roads and, thereby, influence human movement patterns. Most studies in the field of transportation network failure due to urban flooding are focused only on micro-scale, in-situ approaches rather than referring to the holistic impact on the entire transportation system. Moreover, such approaches are failed to address the changes in travel behaviour concerning their trip purpose, mode choice, and income which can be changed due to inundation. Hence, this study presents a novel approach to assess the entire transportation system failure due to urban flooding. Consequently, the impact of urban flooding on human movement patterns was assessed. The proposed framework is developed based on the network centrality measures, namely, betweenness centrality and closeness centrality. The study is predominantly based on Open-Source GIS tools and the case study is carried out in Colombo, Sri Lanka which has the highest concentration of population and transportation network. The hotspots of the failure of the network were statistically and spatially illustrated. The study revealed three key findings; (a) the fragmented network due to inundated road segments triggers the spatial changes in the accessibility, particularly decreasing the accessibility in most of the core areas whereas increasing the accessibility in some peripheral areas which are not significant under the baseline condition (2) the functional changes of the entire transport network occurs due to flooding events (3) the considerable changes in the trip length occurs due to the disruption of transport network links and the impact is mostly notable in long-distance trips compared to short distance trips. The proposed framework can be utilized as a planning tool for both disaster practitioners and infrastructure operators in identifying the flood risk; and prioritizing flood mitigation investments, thereby, making the transportation system more robust to extreme flooding.

A review on passenger emergency evacuation from multimodal transportation hubs

Multimodal transportation hubs serve as transfer points with the function of collecting, transferring, and distributing passengers and play a significant role in the entire multimodal transportation network. In an emergency, the development of an effective and efficient emergency evacuation strategy to evacuate passengers from multimodal transportation hubs is very important. This paper aims to conduct a comprehensive review on passenger emergency evacuations from multimodal transportation hubs, summarize the achievements, identify gaps in existing literature, thus to lay a solid foundation for future studies. This paper first reviewed studies on evacuee behavior characteristics in emergency evacuations, including pedestrian characteristics, pedestrian behavior characteristics, and pedestrian flow characteristics. Then evacuation models, including pedestrian evacuation models and multimodal transportation evacuation models, were investigated. In addition, a retrospective analysis was carried out for evacuation simulation. It is found that while many studies have been conducted on passenger emergency evacuations from multimodal transportation hubs, most of them focus more on evacuating pedestrians from inside to outside of hub buildings; the studies on evacuation at multimodal transfer points are limited. It is also found that most existing studies tried to establish a general model to handle all types of emergency evacuations; in fact, a model would be more efficient if it is just established for a specific emergency and for a specific type of hubs. Also, existing data collection methods may collect biased data; new data collection methods need to be explored to increase the accuracy of data collection. Future study directions include the evacuation at multimodal transfer points, interactive effects between individual pedestrian behavior and pedestrian group behavior, more specific types of emergency evacuations, more accurate data collection methods, and tradeoffs between cost and benefit in emergency evacuations. • Reviewed studies on passenger emergency evacuation from multimodal transportation hubs. • Summarized findings on evacuee behavior, models, and simulations of emergency evacuation studies and analyzed the gaps. • Proposed further studies directions for passenger emergency evacuation from multimodal transportation hubs.

Route choice and parallel routes in subway Networks: A comparative analysis of Beijing and Shanghai

In megacities worldwide, subway systems have become a prevailing transport mode for residents’ daily travel. The expansion of subway networks has given people more route choices and increased the appeal of online maps for route selection. Since few studies have investigated route choices across the entire transport network based on online maps, we introduce the concept of parallel routes with a network analysis approach. Based on that, we offer a comparative analysis between the Beijing and Shanghai subway networks with a network analysis approach combining an online map application programming interface (API). Moreover, we investigate to what extent route choices by subway can be explained by built environment factors within the metro station buffer. The results indicate that online maps do not always offer reasonable route choices due to the complex topology of subway networks. Empirical analysis shows that route choices of the Beijing and Shanghai subway networks follow a distance decay law: the closer to the city center the metro station, the more parallel the routes. Compared with Beijing, the subway network in Shanghai provides more route choices within more parallel routes within the same distance. Furthermore, there is a positive correlation between route choices and land-use mixture around metro stations. In general, our findings are useful for promoting transit-oriented development in megacities.

ОПРЕДЕЛЕНИЕ ПОКАЗАТЕЛЕЙ ОЦЕНКИ ЭФФЕКТИВНОСТИ ИНТЕЛЛЕКТУАЛЬНЫХ ТРАНСПОРТНЫХ СИСТЕМ

Intelligent Transportation Systems (ITS) play a fundamental role in reducing congestion, reducing traffic accidents and improving road safety. Proper evaluation of the effectiveness of these systems is an urgent task in terms of improving the performance of the entire transport network, and the development of a set of evaluation indicators will make it possible to make managerial decisions on planning the development of intelligent transport systems. To test the hypotheses about the possibility of using indicators to assess the effectiveness of ITS, a one-sample t-test was used, during the analysis it was found that the proposed indicators «environmental friendliness and safety», «reliability of the transport network», «competitiveness of public transport» are suitable for assessing intelligent transport systems

An overarching framework to assess the life-time resilience of deteriorating transportation networks in seismic-prone regions

This study develops a comprehensive framework to assess the resilience of transportation networks consisting of deteriorating bridges subjected to earthquake events. For this purpose, the structural capacity of highway bridges is estimated during their service life using a set of detailed finite-element models that simulate the progress of deterioration. The developed models take into consideration the main environmental stressors and determine the extent of capacity loss as a function of time. Based on the degraded state of structural components, seismic fragility analyses are performed to obtain a probabilistic evaluation of the extent of damageability of the existing bridges under seismic events. Since each transportation link normally consists of a number of bridges, the state of damage in the individual bridges is mapped to the corresponding links and a scenario-based approach is employed to estimate the resilience of the entire transportation network. To demonstrate how the consequences of structural degradation can be integrated into the developed framework, the large-scale transportation network of Los Angeles and Orange counties is investigated under a series of aging and earthquake scenarios. The outcome of this study indicates how the estimates associated with the functionality measures of a transportation network can be improved if the age factor is properly integrated into the framework used for resilience assessment.

Tour-based travel demand forecasting model for a university campus

Background and aimThe interest in investigating transportation issues at university campuses has been growing worldwide. Given the university travelers’ unique travel patterns and characteristics influenced mainly by students, forecasting the travel demand of university travelers provides a unique opportunity to understand these patterns and seek solutions for transportation problems at such major trip generators. This study aims at developing a travel demand forecasting model (TDFM) for a university campus, which can be vital for testing alternative solutions, strategies, and policies to tackle transportation problems on university campuses, especially those related to sustainable transportation. MethodologyThe proposed methodology was applied to Sharjah University City (SUC) as a case study. Thus, a tour-based TDFM was developed to replicate the patterns of activity-based travels at SUC. The model was established using the state-of-the-art modeling tool PTV VISUM. Subsequently, it was validated for the baseline year and then applied to forecast future traffic demands. FindingsWith the aim to reduce vehicular traffic volumes, the model was employed to evaluate two scenarios: introducing parking permits and pricing and establishing a park-and-ride facility to serve travelers to campus. These scenarios were compared in terms of several traffic and environmental performance measures. Based on predefined criteria, results highlighted that parking permit enforcement outperformed the park-and-ride facility. The present research may be considered one of the few studies to integrate a tour-based TDFM with a university's entire transportation network, a detailed traffic microsimulation, and an emission evaluation model. ConclusionResults highlighted the effectiveness of the proposed modeling framework in providing reliable solutions for challenging questions that face urban university campus planners under different scenarios. Other universities can follow the methodology presented in this work to develop similar travel forecasting models for their campuses based on their specific travel characteristics.

Open Tools for Analysis of Elements Related to Public Transport Performance. Case Study: Tram Network in Bucharest

The present paper aims to be useful for public transport operators and municipalities, as it should enable them to make decisions and to optimize public transport schedules during peak hours. In this study, we outline the data and the means necessary for the creation and use of a specific database for a dynamic spatial analysis of the public transportation network. This will facilitate the analysis of public transport vehicle operating programs and the simulation of new transport programs using open-source software. This paper delivers the first digital map of the public transport in Bucharest. Using the QGIS software and the PostgresSQL database, (i) we analyzed the accessibility of public transport stops for residential areas (5-min isochrones, corresponding to walking distances of 400 m), and (ii) we determined the correlation of transport vehicle programs with the existing transport network to optimize the headway of vehicles. These two elements were considered for the analysis of public transport performance. The research study was based on the tram network in Bucharest, but it can be easily upscaled for the entire public transport network and may be replicated in other large cities.

GP4: Gaussian Process Proactive Path Planning for the Stochastic on Time Arrival Problem

This paper investigates the stochastic on time arrival (SOTA) problem in Gaussian process (GP) regulated environments. We presume that the travel times of the underlying transportation network follow a multi-variate Gaussian distribution, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</i> . <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> . Gaussian process, and propose a Gaussian process <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">proactive</i> path planner (GP4), which outputs a dynamic routing policy for maximizing the traveller's on-time-arrival probability. When given an instantiated travel time of a certain link, GP is able to analytically represent/predict the posterior travel time distribution over the entire transportation network. With that, we let the ego vehicle ‘proactively’ select the next traversal link, which maximizes the expected stochastic on time arrival probability based on the predicted posterior travel time distribution. Various extensions of GP4 to other forms of travel time distribution assumptions, such as Log-GP and Bi-GP, are proposed and extensive experimental results demonstrate the efficiency and applicability of GP4 to various transportation networks, including a real use case with real traffic data in Chengdu, China.

Optimal schedule recovery for the aircraft gate assignment with constrained resources

Efficient ground handling at airports contributes significantly to the performance of the entire air transport network. In this network, airports are coupled by flights that depend on passenger and crew connections, effective local airport operations, and efficient ground handling resource management. In addition, airport stakeholders must consider different time scales (look-ahead times), process estimates, and both bounded and multiple-dependent solution spaces for their decision-making processes. In this context, we aim to solve the NP-hard problem of combined aircraft turnaround time and airport gate allocation optimization. We developed a hybrid meta-heuristic algorithm based on the Shuffled Frog-Leaping Algorithm (SFLA) and the Grasshopper Optimization Algorithm (GOA). Our hybrid SFLA-GOA approach overcomes the drawback of each algorithm and achieves a preferred solution at a reduced computational cost. We test our approach with a scenario derived from Frankfurt Airport operations, including gate positions, terminal layout, and flight plan information. In all defined problem sizes, the hybrid SFLA-GOA algorithm outperforms an independent implementation of the SFLA algorithm. Also, the SFLA-GOA algorithm provides an improved solution by at least nearly 12% up to 40% over the standard mixed-integer programming solvers.

A method to improve the resilience of multimodal transport network: Location selection strategy of emergency rescue facilities

This paper studies the location selection strategy of emergency rescue facilities in the multimodal transport network to improve the resilience of the network. Based on the overall perspective, we propose a cooperative coverage model. On one hand, it helps network operators improve the recovery speed of the entire multimodal transport network in the event of a disaster. On the other hand, it maximizes the effect of the rescue cost of government managers. But we must note that in most transport networks, failure data is difficult to be collected or is insufficient. Therefore, we propose the premise that the network failure may occur at any point. The rescue demand is quantified by the links/nodes importance, which is calculated by the multi-attribute decision-making method based on hesitant intuitionistic fuzzy set-technique for order preference by similarity to an ideal solution (TOPSIS). Then, a multi-objective non-linear programming model is established, and fast non-dominated sorting genetic algorithm-cellular automata (NSGA-II-CA) is designed to solve the model. Taking the multimodal transport network in the Sichuan-Tibet region of China as an example, calculation and analysis are performed to verify the effectiveness and advancement of the proposed model and algorithm. The innovation of this paper is to propose a method of emergency rescue facility location from the perspective of global optimization.

Coordinated Control of Distributed Traffic Signal Based on Multiagent Cooperative Game

In the adaptive traffic signal control (ATSC), reinforcement learning (RL) is a frontier research hotspot, combined with deep neural networks to further enhance its learning ability. The distributed multiagent RL (MARL) can avoid this kind of problem by observing some areas of each local RL in the complex plane traffic area. However, due to the limited communication capabilities between each agent, the environment becomes partially visible. This paper proposes multiagent reinforcement learning based on cooperative game (CG-MARL) to design the intersection as an agent structure. The method considers not only the communication and coordination between agents but also the game between agents. Each agent observes its own area to learn the RL strategy and value function, then concentrates the Q function from different agents through a hybrid network, and finally forms its own final Q function in the entire large-scale transportation network. The results show that the proposed method is superior to the traditional control method.

Radiation Effect of Urban Agglomeration’s Transportation Network: Evidence from Chengdu–Chongqing Urban Agglomeration, China

Recent years have seen the global proliferation and integration of transportation systems in urban agglomeration (UA), suggesting that transportation networks have become more prominent in the sustainable development of UA. Core cities play a radiating and driving role in affecting their adjacent cities to formulate transportation networks. Such a phenomenon is called the radiation effect of transportation networks and can be imaged using a field strength model as proposed in the study. The field strength model was verified using the Chengdu–Chongqing urban agglomeration (CCUA) as a case. Case data concerning transportation routes and traffic volume were collected for the past 20 years. The data analyses results indicate a relatively stable pattern of transportation networks in the UA. UA cities’ radiation effects follow the same compactness trend. The core cities’ radiation spheres go beyond their territories, and they can envelop the surrounding cities, highlighting the core cities’ dominance in the entire transportation network. Moreover, two development stages of UA transportation—focus and spillover—are also identified. This study contributes to the literature by providing an innovative quantitative method to detect the interaction between a city’s transportation system and peripheral cities or regions. The radiation effect of cities’ transportation systems should be considered in the UA transportation development plan, so as to meet the needs of spatial structure planning and coordinated development of the UA.

Port Connectivity Model in The Perspective of Multimodal Transport: A Conceptual Framework

As an archipelagic country, the use of several modes or multimodal freight transport in Indonesia is indispensable. As a place of “interchanging,” Port is an essential element in a transportation system that supports a region’s economy and becomes more in the region island where incoming and outgoing goods rely on it. Port connectivity is not just about how “good” the Port is connected to the maritime transportation network and reached by regular lines services but also contributes to the entire transport network. Generally, the higher port connectivity is, the more attractive it is to facilitate cargo transportation and reduce transportation costs and time. Port connectivity is very complex, and it will be more useful if analysed from more perspective by using comprehensive analysis. This paper proposes the conceptual framework port connectivity in the multimodal perspective that sees from three aspects: maritime connectivity, connectivity of port with the hinterland, and connectivity at the Port and using the same measurement such as generalized transport cost. Analysis on various aspects will give a better understanding of port connectivity. Conceptual framework consists of three stages, the first stage is defining the definition of connectivity, seconds stage is connectivity analysis, and the last stage is synthetic of results. The importance of conceptualizing port connectivity is because there is still a lack of research on port connectivity. It is mostly analysed only on one aspect, as we know that port connectivity is very complicated. It will be more useful if analysed from a more different point of view with a comprehensive analysis.

Vulnerability Assessment of the Urban Rail Transit Network Based on Travel Behavior Analysis

Vulnerability assessment plays a crucial role in the management of complex and large-scale urban rail transit networks (URTNs). Even a temporary disruption may paralyze an entire public transportation network under a cascading failure. In the terms of vulnerability of the URTN, most studies have focused on changes in URTN topological characteristics and travel costs under disturbances, thereby neglecting the impact of alternative public transportation modes on passenger flow redistribution within the URTN. Therefore, in this study, considering the impact of changes in travel costs and modes on passenger flow redistribution, a novel model is proposed to analyze the cascading failure of weighted URTNs. Furthermore, adopting the estimated operation interruption time of the station (EOITS) to characterize the system disturbance intensity, the dynamic vulnerability of the URTN is simulated and analyzed. The results show that the EOITS exerts a major impact on the vulnerability of URTNs. With increasing of EOITS, the travel behavior of passengers becomes more diverse, and the process of cascading failure in URTNs also becomes more challenging to control. This research has implications for managers in terms of implementing of protective measures to mitigate the cascading failure risk and avert extreme catastrophes.