References of "Laskaris, Georgios 50022041"
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See detailReal Time Holding Control for Multiline Networks
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

Poster (2020, January 12)

We introduce a rule based multiline holding criterion for regularity in branch and trunk networks accounting for all passenger groups. On the shared transit corridor, we consider synchronization at the ... [more ▼]

We introduce a rule based multiline holding criterion for regularity in branch and trunk networks accounting for all passenger groups. On the shared transit corridor, we consider synchronization at the merging or the diverging stop. The decision between holding for regularity or synchronization is taken by comparing the expected passenger cost of each control action. The proposed criterion is tested through simulation in a synthetic double fork network with different shares of transferring passengers, control schemes for regularity and synchronization. The results show that multiline control outperforms the state of the art schemes at the network level, stemming from benefits occurring at the first part of the route and the shared transit corridor and a 3.5% more stable joint headway compared to the other schemes. Additionally, it is advised to perform the synchronization at the diverging stop, as it proves to result in a more stable transferring time equal to the joint frequency of the corridor while reducing the transfer time variability up to -42.7%. [less ▲]

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See detailPrinciples for setting single line and multiline control based on network characteristics
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

Scientific Conference (2019, September)

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See detailMULTILINE HOLDING CONTROL AND INTEGRATION OF COOPERATIVE ITS
Laskaris, Georgios UL

Doctoral thesis (2019)

Transportation is an important sector of the global economy. The rapid urbanization and urban sprawl comes with continuous demand for additional transportation infrastructure in order to satisfy the ... [more ▼]

Transportation is an important sector of the global economy. The rapid urbanization and urban sprawl comes with continuous demand for additional transportation infrastructure in order to satisfy the increasing and variable demand. Public transportation is a major contributor in alleviating traffic congestion in the modern megacities and provide a sustainable alternative to car for accessibility. Public transport operation is inherently stochastic due to the high variability in travel times and passenger demand. This yields to disruptions and undesired phenomena such as vehicles arriving in platoons at stops. Due to the correlation between the headway between vehicles and passenger demand, bunching leads to long waiting time at stops, overcrowded vehicles, discomfort for the passengers and from the operators side poor management of available resources and overall a low of service of the system. The introduction of intelligent transport systems provided innovative applications in order to monitor the operation, collect data and react dynamically to any disruption of the transit system. Advanced Public Transport Systems extended the range of control strategies and their objectives beyond schedule adherence and reliance on historical data alone. Among strategies, holding is a thoroughly investigated and applicable control strategy. With holding, a vehicle is instructed to remain at a designated stop for an additional amount of time after the completion of dwell time, until a criterion is fulfilled. Depending on the characteristics of the line the criterion aim for schedule adherence or regularity or minimization of passenger costs and its components. So far, holding is used for regulating single line operation. Beyond single line, it has been used for transfer synchronization at transfer hubs and recently has been extended to regulate the operation on consecutive stops that are served by multiple lines. The first part of this dissertation is dedicated to real time holding control of multiple lines. A rule based holding criterion is formulated based on the passenger travel time that accounts for the passengers experiencing the control action. Total holding time is estimated based on the size of all passenger groups that interact. The formulated criterion can be applied on all different parts of trunk and branch network. Additionally, the criterion is coupled with a rule based criterion for synchronization and the decision between the two is taken based on the passenger cost. The criterion has been tested for different trunk and branch networks and compared with different control schemes and its performance has been assessed using regularity indices as well as passenger cost indicators for the network in total but also per passenger group. Finally, an analysis has been conducted in order to define under which network and demand configuration multiline control can be preferred over single line control. Results shown that under specific demand distributions multiline control can outperform single line control in network level. Continuously new technologies are introduced to transit operation. Recently, Cooperative Intelligent Transport Systems utilized in the form of Driver Advisory Systems (DAS) shown that can provide the same level of priority with transit signal priority without changing the time and the phases of a traffic light. However, until now the available DASs focus exclusively on public transport priority neglecting completely the sequence of the vehicles and the effects on the operation. In the second part of the dissertation, two widely used DASs are combined with holding in order to meet both the objective of reducing the number of stops at traffic signals and at the same time maintain regularity. Two hybrid controllers are introduced, a combination of two holding criteria and a combination of holding and speed advisory. Both controllers are tested using simulation in comparison to the independent application of the controllers and different levels of transit signal priority. The hybrid controllers can drastically reduce transit signal priority requests while they manage to achieve both objectives. [less ▲]

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See detailA real time hybrid controller for regulating bus operations and reducing stops at signals
Laskaris, Georgios UL; Seredynski, Marcin; Viti, Francesco UL

Scientific Conference (2019, June)

We propose a hybrid controller which consists of holding and a Driver Advisory System (DAS). It combines the objectives of seeking the regularization of operation and the reduction of stop and go actions ... [more ▼]

We propose a hybrid controller which consists of holding and a Driver Advisory System (DAS). It combines the objectives of seeking the regularization of operation and the reduction of stop and go actions at signalized intersections. A simple headway based holding criterion is applied at stops to define the time needed to maintain even spaced headways between buses and additionally a speed recommendation is given to traverse during green indication at the downstream signalized intersection. The controller is tested using simulation for a bus line of the city of Luxembourg, Luxembourg and compared to a benchmark scenario, the single application of bus holding, two advisory systems and different levels of transit signal priority. Results show that there are additional benefits compared to traditional holding in terms of regularity while similar performance to strong transit signal priority is achieved in terms of time spent at traffic lights. [less ▲]

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See detailMixed hybrid and electric bus dynamic fleet management in urban networks: a model predictive control approach
Rinaldi, Marco UL; Picarelli, Erika UL; D'Ariano, Andrea et al

Scientific Conference (2019, June)

Abstract—Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport, are increasingly becoming key objectives for policymakers worldwide. In order to jointly ... [more ▼]

Abstract—Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport, are increasingly becoming key objectives for policymakers worldwide. In order to jointly achieve these goals, careful consideration should be put on the operational cost and management of PT services, in order to promote the adoption of green mobility solutions and advanced management techniques by operators. In this work we develop a dynamic fleet management approach for next generation Public Transportation systems, considering the instance of mixed electric / hybrid fleet. Our objective is that of investigating to what extent electrification, coupled with optimal fleet management, can yield operational cost savings for PT operators, explicitly considering real-time disturbances, including delays, service disruptions etc. We propose a Mixed Integer Linear Program to address the problem of optimal scheduling of a mixed fleet of electric and hybrid / non-electric buses, and employ it as predictor in a Model Predictive Control approach. Test results based upon a real-life scenario showcase how the proposed approach is indeed capable of yielding a sizable reduction in operational costs, even when considerable disturbances arise from the underlying system. [less ▲]

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See detailAnalysis of Cooperative Bus Priority at Traffic Signals
Seredynski, Marcin; Laskaris, Georgios UL; Viti, Francesco UL

in IEEE Transactions on Intelligent Transportation Systems (2019)

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See detailTowards Optimized Deployment of Electric Bus Systems Using Cooperative ITS
Laskaris, Georgios UL; Seredynski, Marcin; Viti, Francesco UL

Poster (2019, January)

In this paper we analyze the impact of using cooperative intelligent transportation systems (C-ITS) to manage electrical bus systems. A simulation-based study is presented where three control strategies ... [more ▼]

In this paper we analyze the impact of using cooperative intelligent transportation systems (C-ITS) to manage electrical bus systems. A simulation-based study is presented where three control strategies are used to regulate the operations of a line, namely bus holding, Green Light Optimal Dwell Time Adaptation (GLODTA) and Transit Signal Priority (TSP). The results show, using a realistic scenario of a major line in Luxembourg City, that buses are efficiently operated without necessarily providing additional priority to public transport, hence without negatively affecting the capacity of the private vehicles system. Benefits in terms of headway regulations, energy consumption and travel time variance reductions are quantified. [less ▲]

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See detailMixed hybrid and electric bus dynamic fleet management in urban networks: a model predictive control approach
Rinaldi, Marco UL; Picarelli, Erika; Laskaris, Georgios UL et al

Scientific Conference (2019, January)

Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport, are increasingly becoming key objectives for policymakers worldwide. In order to jointly achieve ... [more ▼]

Reducing pollutant emissions and promoting sustainable mobility solutions, including Public Transport, are increasingly becoming key objectives for policymakers worldwide. In order to jointly achieve these goals, careful consideration should be put on the operational cost and management of PT services, in order to promote the adoption of green mobility solutions and advanced management techniques by operators. In this work we develop a dynamic fleet management approach for next generation Public Transportation systems, considering the instance of mixed electric / hybrid fleet. Our objective is that of investigating to what extent electrification, coupled with optimal fleet management, can yield operational cost savings for PT operators, explicitly considering real-time disturbances, including delays, service disruptions etc. We propose a Mixed Integer Linear Program to address the problem of optimal scheduling of a mixed fleet of electric and hybrid / non-electric buses, and employ it as predictor in a Model Predictive Control approach. Test results based upon a real-life scenario showcase how the proposed approach is indeed capable of yielding a sizable reduction in operational costs, even when considerable disturbances arise from the underlying system. [less ▲]

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See detailOptimal dispatching of electric and hybrid buses subject to scheduling and charging constraints
Rinaldi, Marco UL; Parisi, Federico; Laskaris, Georgios UL et al

Scientific Conference (2018, November)

We consider the problem of optimally determining the sequence of electric and hybrid buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy ... [more ▼]

We consider the problem of optimally determining the sequence of electric and hybrid buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities). The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by practical sets of constraints, ranging from scheduling adherence to discharge- recharge dynamics. Individual operational costs at the bus level and at the trip level are fully parametrized, allowing for extensive sensitivity analysis. We investigate a real-life case study based on the city of Luxembourg, where two charging stations have been installed in the central station’s bus terminal. Experimental results show that, while full electrification is indeed possible, the required fleet size depends strongly on the given line(s) timetable. [less ▲]

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See detailReal time multiline holding control for networks with shared transit corridor
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

Scientific Conference (2018, September 05)

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See detailDecompositions of the optimal dispatching problem of electric and electric-hybrid buses with energy constraints for Luxembourg City
Picarelli, Erika; Rinaldi, Marco UL; Viti, Francesco UL et al

Scientific Conference (2018, September)

We are a team of engineers working on a concrete project of Mobility in Luxembourg. We want to solve the problem of optimally determining the sequence of electric and hybrid electric buses, considering ... [more ▼]

We are a team of engineers working on a concrete project of Mobility in Luxembourg. We want to solve the problem of optimally determining the sequence of electric and hybrid electric buses, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities) and at the same time ensure a high level of quality of service for the user satisfaction. The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by twenty sets of constraints, ranging from scheduling adherence to discharge-recharge dynamics. Individual operational costs at the bus level (cost of running an electric / non-electric bus per km, cost of recharging) and at the trip level (penalty due to failed schedule adherence) are fully parametrised, allowing for extensive sensitivity analysis. We investigate a real-life case study based in the city of Luxembourg, where the objective is to reach the all-electric mode for principal urban buses network. Through the model we investigate: the minimum amount of electric buses necessary to perform a day’s schedule for two currently partially electrified lines, without resorting to conventional internal combustion alternatives; the impact of electrifying two additional lines, specifically considering the trade-offs related to either adding new buses or new charging stations at the bus terminal. Finally, we studied how to best decompose the overall problem in several smaller problems, to be able to solve also realistic scenarios and using large real data sets from the Mobility Data owner of Luxembourg. We analysed and compared two kinds of decomposition: a bus line-based decomposition, and a time-based decomposition. [less ▲]

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See detailA holding control strategy for diverging bus lines
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

Scientific Conference (2018, July 24)

We introduce a holding criterion for network configurations with lines that operate jointly along a common corridor and then individually diverge. The proposed holding decision rule accounts for all ... [more ▼]

We introduce a holding criterion for network configurations with lines that operate jointly along a common corridor and then individually diverge. The proposed holding decision rule accounts for all different passengers groups in the overlapping segment and takes care of the transition to individual line operation. The holding rule is evaluated using simulation for different demand levels and segmentations and compared with other control schemes for a real-world network. Results show that gains in overall network performance as well as for specific passenger groups can be achieved under specific demand distributions. [less ▲]

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See detailOptimal multi-line bus dispatching at terminals with electric charging scheduling constraints
Rinaldi, Marco UL; Parisi, Federico; D'Ariano, Andrea et al

Scientific Conference (2018, July)

We consider the problem of optimally determining the sequence of electric and conventional internal combustion buses departing from a multi-line bus terminal, considering both service constraints ... [more ▼]

We consider the problem of optimally determining the sequence of electric and conventional internal combustion buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities). The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by twenty sets of constraints, ranging from scheduling adherence to discharge-recharge dynamics. Individual operational costs at the bus level (cost of running an electric / non electric bus per km, cost of recharging) and at the trip level (penalty due to failed schedule adherence) are fully parametrised, allowing for extensive sensitivity analysis. We investigate a real-life case study based in the city of Luxembourg, where two charging stations have been installed in the central station’s bus terminal. Through the model we investigate: i) the minimum amount of electric buses necessary to perform a day’s schedule for two currently partially electrified lines, without resorting to conventional internal combustion alternatives; ii) the impact of electrifying two additional lines, specifically considering the trade-offs related to either adding new buses or new charging stations at the bus terminal. [less ▲]

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See detailTowards Optimised Deployment of Electric Bus Systems with On-Route Charging using Cooperative ITS
Laskaris, Georgios UL; Seredynski, Marcin; Viti, Francesco UL

Scientific Conference (2018, July)

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See detailMultiline holding based control for lines merging to a shared transit corridor
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

in Transportmetrica B: Transport Dynamics (2018)

In transit corridors, multiple lines share a sequence of consecutive stops to provide higher joint frequency in higher demand areas. A key challenge is to coordinate the transition from single line to ... [more ▼]

In transit corridors, multiple lines share a sequence of consecutive stops to provide higher joint frequency in higher demand areas. A key challenge is to coordinate the transition from single line to joint operation. A holding control strategy aimed at minimizing passenger travel times is introduced for lines merging into a shared corridor, accounting for the coordination of vehicle arrivals from the merging lines as well as the regularity of each line. The criterion is tested using an artificial network and a real-world network to analyze the impact of demand distribution and compare cooperative versus single line control. We illustrate how the real-time strategy yields overall passenger gains, depending on the composition of different user groups. Results are assessed based on operation and passenger performance indicators and show that coordination is achieved. When combined with joint control in the common part, the proposed approach achieves consistentnetwork-wide travel time benefits. [less ▲]

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See detailExperimental analysis of eGLOSA and eGLODTA transit control strategies
Giorgione, Giulio UL; Viti, Francesco UL; Rinaldi, Marco UL et al

in Proceedings of the 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems, MT-ITS 2017 (2017)

Battery powered electric buses have higher energy efficiency, lower emissions and noise when compared to buses with internal combustion engines. However, due to battery charging requirements, their large ... [more ▼]

Battery powered electric buses have higher energy efficiency, lower emissions and noise when compared to buses with internal combustion engines. However, due to battery charging requirements, their large-scale integration into public transport operations is more complex. This study proposes a novel concept supporting said integration via new control strategies, dubbed e-GLOSA and e-GLODTA. These strategies extend the existing Green Light Optimal Speed and Dwell Time Systems (GLOSA/GLODTA) to account for the specific needs of electric buses. That is, they include the goals of minimizing the energy consumption between charging stations, and maximizing available charging time. At the same time, interference with schedule requirements is minimized. The formulated heuristics are tested on a Bus Rapid Transit (BRT) corridor case study, where different scenarios—such as placement of charging stations and bus regularity—are studied to assess under which conditions each action (maintain speed, accelerate or dwell for a longer time at a stop) is beneficial. Results show that eGLOSA contributes to schedule adherence while eGLODTA allows satisfying charging time constraints. [less ▲]

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See detailA real-time holding decision rule accounting for passenger travel cost
Laskaris, Georgios UL; Cats, Oded; Jenelius, Erik et al

Scientific Conference (2016, November 04)

Holding has been extensively investigated as a strategy to mitigate the inherently stochastic nature of public transport operations. Holding focuses on either regulating vehicle headways using a rule ... [more ▼]

Holding has been extensively investigated as a strategy to mitigate the inherently stochastic nature of public transport operations. Holding focuses on either regulating vehicle headways using a rule-based approach or minimizing passenger travel cost by employing optimization models. This paper introduces a holding decision rule that explicitly addresses passenger travel cost. The decision to hold relies on the passenger demand distribution along the line. The passenger cost holding rule is tested using simulation for a high frequency bus line in Stockholm, Sweden and is compared with a nocontrol scheme and the currently used headway-based strategy. The results indicate that the new decision rule results in relatively minor reductions of passenger cost compared to the currently adopted strategy, and that it allocates the greatest share of holding time at the beginning of the route. [less ▲]

Detailed reference viewed: 108 (7 UL)