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Efthymis Papadopoulos
Transport Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece

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Journal article
Published: 17 March 2021 in European Transport Research Review
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Background COVID-19 pandemic is a challenge that the world had never encountered in the last 100 years. In order to mitigate its negative effects, governments worldwide took action by prohibiting at first certain activities and in some cases by a countrywide lockdown. Greece was among the countries that were struck by the pandemic. Governmental authorities took action in limiting the spread of the pandemic through a series of countermeasures, which built up to a countrywide lockdown that lasted 42 days. Methodology This research aims at identifying the effect of certain socioeconomic factors on the travel behaviour of Greek citizens and at investigating whether any social groups were comparatively less privileged or suffered more from the lockdown. To this end, a dynamic online questionnaire survey on mobility characteristics was designed and distributed to Greek citizens during the lockdown period, which resulted in 1,259 valid responses. Collected data were analysed through descriptive and inferential statistical tests, in order to identify mobility patterns and correlations with certain socioeconomic characteristics. Additionally, a Generalised Linear Model (GLM) was developed in order to examine the potential influence of socioeconomic characteristics to trip frequency before and during the lockdown period. Results Outcomes indicate a decisive decrease in trip frequencies due to the lockdown. Furthermore, the model’s results indicate significant correlations between gender, income and trip frequencies during the lockdown, something that is not evident in the pre-pandemic era.

ACS Style

Ioannis Politis; Georgios Georgiadis; Anastasia Nikolaidou; Aristomenis Kopsacheilis; Ioannis Fyrogenis; Alexandros Sdoukopoulos; Eleni Verani; Efthymis Papadopoulos. Mapping travel behavior changes during the COVID-19 lock-down: a socioeconomic analysis in Greece. European Transport Research Review 2021, 13, 1 -19.

AMA Style

Ioannis Politis, Georgios Georgiadis, Anastasia Nikolaidou, Aristomenis Kopsacheilis, Ioannis Fyrogenis, Alexandros Sdoukopoulos, Eleni Verani, Efthymis Papadopoulos. Mapping travel behavior changes during the COVID-19 lock-down: a socioeconomic analysis in Greece. European Transport Research Review. 2021; 13 (1):1-19.

Chicago/Turabian Style

Ioannis Politis; Georgios Georgiadis; Anastasia Nikolaidou; Aristomenis Kopsacheilis; Ioannis Fyrogenis; Alexandros Sdoukopoulos; Eleni Verani; Efthymis Papadopoulos. 2021. "Mapping travel behavior changes during the COVID-19 lock-down: a socioeconomic analysis in Greece." European Transport Research Review 13, no. 1: 1-19.

Journal article
Published: 03 February 2021 in Safety
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Intersection safety and drivers’ behavior are strongly interrelated, especially when the latter are located in dilemma zone. This paper explores, among others, the main factors affecting driver behavior, such as distance to stop line, approaching speed and acceleration/deceleration, and two additional factors, namely, driver’s aggressiveness and driver’s relative position at the onset of the yellow signal. Field data were collected using unmanned aerial vehicle (UAV) technology. Two binary choice models were developed, the first relying on observed data and the latter enriched by the latent factor drivers’ aggressiveness and the vehicles’ relative position. Drivers were classified to aggressive and non-aggressive ones using a latent class model that combined approaching speed and acceleration/deceleration data. Drivers were further grouped according to their expected reaction/decision to stop or cross the intersection in relation to their relative position. Both models equally explain drivers’ decisions adequately, but the second one offers additional explanatory power attributed to aggressiveness. Being able to identify the level of aggressiveness among the drivers enables the calculation of the probability that drivers will cross the intersection even if caught in a dilemma zone or in a zone in which the obvious decision is to stop. Such findings can be valuable when designing a signalized intersection and the traffic time settings, as well as the posted speed limit.

ACS Style

Panagiotis Papaioannou; Efthymis Papadopoulos; Anastasia Nikolaidou; Ioannis Politis; Socrates Basbas; Eleni Kountouri. Dilemma Zone: Modeling Drivers’ Decision at Signalized Intersections against Aggressiveness and Other Factors Using UAV Technology. Safety 2021, 7, 11 .

AMA Style

Panagiotis Papaioannou, Efthymis Papadopoulos, Anastasia Nikolaidou, Ioannis Politis, Socrates Basbas, Eleni Kountouri. Dilemma Zone: Modeling Drivers’ Decision at Signalized Intersections against Aggressiveness and Other Factors Using UAV Technology. Safety. 2021; 7 (1):11.

Chicago/Turabian Style

Panagiotis Papaioannou; Efthymis Papadopoulos; Anastasia Nikolaidou; Ioannis Politis; Socrates Basbas; Eleni Kountouri. 2021. "Dilemma Zone: Modeling Drivers’ Decision at Signalized Intersections against Aggressiveness and Other Factors Using UAV Technology." Safety 7, no. 1: 11.

Conference paper
Published: 04 November 2020 in Advances in Intelligent Systems and Computing
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In order for the bicycle usage to be increased, cities need to provide users, inter alia, with high-quality infrastructure. Yet, there is not a generally accepted approach to optimize placemaking of such infrastructure in the urban environment, especially on the micro-level. This paper presents a methodological approach for assessing alternative bicycle lane implementations in urban networks, from a micro perspective. Specifically, a multicriteria analysis-based methodology is proposed, which accounts for specific criteria, including geometric characteristics of road network (i.e. road width and slope), effect on on-street parking supply, public acceptance, land-use and built environment characteristics, etc. These criteria are weighted, in line with their relative importance, by micromobility and sustainable urban mobility experts. This methodology is applied to the city of Karditsa, Greece, where two (2) alternative streets were examined in terms of hosting a different type of bicycle lane that would complement the existing cycle route network. The MCA results suggested that safety forms the major factor that most heavily affect the final placemaking and type of the bicycle lane decision. The proposed methodology could contribute towards successful bicycle routing, forming a useful tool for traffic engineers and local authorities.

ACS Style

Ioannis Politis; Efthymis Papadopoulos; Ioannis Fyrogenis; Zoi Fytsili. A Multi-criteria-Based Methodology for Assessing Alternative Bicycle Lane Implementation Solutions in Urban Networks. Advances in Intelligent Systems and Computing 2020, 435 -444.

AMA Style

Ioannis Politis, Efthymis Papadopoulos, Ioannis Fyrogenis, Zoi Fytsili. A Multi-criteria-Based Methodology for Assessing Alternative Bicycle Lane Implementation Solutions in Urban Networks. Advances in Intelligent Systems and Computing. 2020; ():435-444.

Chicago/Turabian Style

Ioannis Politis; Efthymis Papadopoulos; Ioannis Fyrogenis; Zoi Fytsili. 2020. "A Multi-criteria-Based Methodology for Assessing Alternative Bicycle Lane Implementation Solutions in Urban Networks." Advances in Intelligent Systems and Computing , no. : 435-444.

Journal article
Published: 05 October 2020 in Sustainability
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In this paper, we explore users’ intentions to use bike-sharing systems (BSS) compared to traditional competitive transport modes—private car, bus and walking. Fueled by the increasingly rampant growth of shared economy and Information and Communication Technology (ICT), shared mobility is gaining increasing traction. The numbers of shared mobility schemes are rapidly growing worldwide and are accompanied by changes in the traditional vehicle ownership model. In order to pinpoint the factors that strongly affect the willingness to use BSS, a stated preference survey among car and bus users as well as pedestrians was designed and conducted. Binary logit models of the choice between the currently preferred transportation modes and BSSs were developed, for short and long-duration trips, respectively. The results highlight a distinctive set of factors and patterns affecting the willingness to adopt bike-sharing: choice is most sensitive to travel time and cost of the competitive travel options. In general, users are more willing to make the switch to a BSS, especially for short trip durations, when their typical mode of transport becomes more expensive. Bike-sharing also seems to be a more attractive option for certain user socio-demographic groups per mode and trip duration (age, education level, employment status, household income). Trip characteristics such as trip purpose and frequency were also found to affect the willingness to choose BSS. In general, BSS seem to mainly attract bus users and pedestrians, while car users may use BSS more sparingly, mainly for commuting purposes.

ACS Style

Ioannis Politis; Ioannis Fyrogenis; Efthymis Papadopoulos; Anastasia Nikolaidou; Eleni Verani. Shifting to Shared Wheels: Factors Affecting Dockless Bike-Sharing Choice for Short and Long Trips. Sustainability 2020, 12, 8205 .

AMA Style

Ioannis Politis, Ioannis Fyrogenis, Efthymis Papadopoulos, Anastasia Nikolaidou, Eleni Verani. Shifting to Shared Wheels: Factors Affecting Dockless Bike-Sharing Choice for Short and Long Trips. Sustainability. 2020; 12 (19):8205.

Chicago/Turabian Style

Ioannis Politis; Ioannis Fyrogenis; Efthymis Papadopoulos; Anastasia Nikolaidou; Eleni Verani. 2020. "Shifting to Shared Wheels: Factors Affecting Dockless Bike-Sharing Choice for Short and Long Trips." Sustainability 12, no. 19: 8205.

Conference paper
Published: 02 October 2020 in Transactions on Petri Nets and Other Models of Concurrency XV
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The new generation of bike-sharing services without docking stations is spreading around large cities of the world. The paper provides a technical specification of a platform, for managing a dockless bike sharing system. The bicycles of the platform are equipped with GPS devices and GPRS cards that can transmit, over the Internet, their exact location at any time. We collect and store all events derived from a user’s interaction with the system and in addition the trajectory points of a route during a rent order. The platform aims to fulfill the requirements of bikers, administrators and the research community through the collection, analysis and exploitation of bike sharing data. In the context of the platform, an app for smart devices is implemented for citizens to access the system. A dashboard is offered to the administrator as a valuable tool to inspect, promote the system and evaluate its usage. Last, all stored anonymised data can be accessible for further analysis by the research community through a REST API. The i-CHANGE platform is currently pilot tested in the city of Thessaloniki, Greece.

ACS Style

Lazaros Apostolidis; Symeon Papadopoulos; Maria Liatsikou; Ioannis Fyrogenis; Efthymis Papadopoulos; George Keikoglou; Konstantinos Alexiou; Nasos Chondros; Ioannis Kompatsiaris; Ioannis Politis. i-CHANGE: A Platform for Managing Dockless Bike Sharing Systems. Transactions on Petri Nets and Other Models of Concurrency XV 2020, 12250, 851 -867.

AMA Style

Lazaros Apostolidis, Symeon Papadopoulos, Maria Liatsikou, Ioannis Fyrogenis, Efthymis Papadopoulos, George Keikoglou, Konstantinos Alexiou, Nasos Chondros, Ioannis Kompatsiaris, Ioannis Politis. i-CHANGE: A Platform for Managing Dockless Bike Sharing Systems. Transactions on Petri Nets and Other Models of Concurrency XV. 2020; 12250 ():851-867.

Chicago/Turabian Style

Lazaros Apostolidis; Symeon Papadopoulos; Maria Liatsikou; Ioannis Fyrogenis; Efthymis Papadopoulos; George Keikoglou; Konstantinos Alexiou; Nasos Chondros; Ioannis Kompatsiaris; Ioannis Politis. 2020. "i-CHANGE: A Platform for Managing Dockless Bike Sharing Systems." Transactions on Petri Nets and Other Models of Concurrency XV 12250, no. : 851-867.

Conference paper
Published: 02 October 2020 in Transactions on Petri Nets and Other Models of Concurrency XV
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In this paper we explore factors that affect Bike Sharing System (BSS) usage and how they differentiate between discrete groups of potential users. BSS have known a rampant growth during recent years, through technological advances, re-evaluated business models and reinvention of the mean’s utility. Yet, for a realized use of dockless BSS and a successful integration in the urban mobility ecosystem to be achieved, the factors that promote willingness to use them need to be explored. By using a sample of 500 stated preference data, classification trees and random forest models are built for three groups of potential BSS users; car users, bus users and pedestrians. Among the considered factors are BSS cost gains, BSS In Vehicle Time (IVT) and Out of Vehicle Time (OVT) gains, trip frequency, purpose and duration. More specific, it was found that BSS potential, increases for short duration trips of up to 21 min for car users. Bus users and pedestrians were found to be more likely to choose a BSS option for a higher cost up to 0,60 and 0,75 euros respectively. On the other side sociodemographic characteristics such as household income, gender, education level and occupation did not found to be the dominant factors for the mode choice decision. OVT is found only to be relatively important for bus users, while the cost gains are comparatively more significant for bus users and pedestrians.

ACS Style

Ioannis Politis; Ioannis Fyrogenis; Efthymis Papadopoulos; Anastasia Nikolaidou; Eleni Verani. Understanding Willingness to Use Dockless Bike Sharing Systems Through Tree and Forest Analytics. Transactions on Petri Nets and Other Models of Concurrency XV 2020, 12250, 784 -795.

AMA Style

Ioannis Politis, Ioannis Fyrogenis, Efthymis Papadopoulos, Anastasia Nikolaidou, Eleni Verani. Understanding Willingness to Use Dockless Bike Sharing Systems Through Tree and Forest Analytics. Transactions on Petri Nets and Other Models of Concurrency XV. 2020; 12250 ():784-795.

Chicago/Turabian Style

Ioannis Politis; Ioannis Fyrogenis; Efthymis Papadopoulos; Anastasia Nikolaidou; Eleni Verani. 2020. "Understanding Willingness to Use Dockless Bike Sharing Systems Through Tree and Forest Analytics." Transactions on Petri Nets and Other Models of Concurrency XV 12250, no. : 784-795.

Conference paper
Published: 12 December 2018 in Advances in Intelligent Systems and Computing
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Road accidents form a leading cause of death globally. Despite the recent progress that have been made, Greece continues to be among the worst performing countries in the EU, in respect to road safety. This research deals with the spatial analysis and modelling of road accidents, in the metropolitan area of Thessaloniki, Greece. Total accidents pertained to be the dependent variable whereas various land use, demographic and macroscopic traffic modelling data were considered as explanatory variables. As required, the model inputs were aggregated to the TAZ level. First, a properly specified OLS model was developed, followed by the application of the GWR method. Unlike OLS models that are considered to be global, GWR allows the relationships modelled to vary over space, in line with spatial non-stationarity of social processes. This latter approach, improves the goodness of fit statistics of the OLS model and is helpful for policy-making at a local scale. A number of interesting correlations have been found, between accidents and a variety of statistically significant factors, such as the number of leisure establishments, pedestrian volume and length of particular types of roads. The GWR model built, uncovered the spatially varying relationships, dictating specific areas where these explanatory variables are strong or low predictors of the dependent variable.

ACS Style

Efthymis Papadopoulos; Ioannis Politis. Combining Land Use, Traffic and Demographic Data for Modelling Road Safety Performance in Urban Areas. Advances in Intelligent Systems and Computing 2018, 71 -78.

AMA Style

Efthymis Papadopoulos, Ioannis Politis. Combining Land Use, Traffic and Demographic Data for Modelling Road Safety Performance in Urban Areas. Advances in Intelligent Systems and Computing. 2018; ():71-78.

Chicago/Turabian Style

Efthymis Papadopoulos; Ioannis Politis. 2018. "Combining Land Use, Traffic and Demographic Data for Modelling Road Safety Performance in Urban Areas." Advances in Intelligent Systems and Computing , no. : 71-78.