| 1. |
- Beza, Abebe Dress, et al.
(författare)
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How PTV Vissim Has Been Calibrated for the Simulation of Automated Vehicles in Literature?
- 2022
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Ingår i: Advances in Civil Engineering / Hindawi. - : Hindawi Limited. - 1687-8086 .- 1687-8094. ; 2022
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Forskningsöversikt (refereegranskat)abstract
- Recently, in the literature, microscopic simulation is one of the most attractive methods in impact assessment of automated vehicles (AVs) on traffic flow. AVs can be divided into different categories, each having different driving characteristics. Hence, calibrating microscopic simulators for different AV categories could be challenging in AVs' impact assessment. The PTV Vissim microscopic traffic simulation software has been calibrated for simulating diverse types of AVs in a large body of literature. There are two main streams of studies in literature adapting AVs' driving behaviors in Vissim following either internal (i.e., adjusting the parameters of the Vissim's default driving behavior models) or external (i.e., adapting AVs' behavior through external VISSIM interfaces) modeling approaches. The current paper investigates how the PTV Vissim has been internally calibrated for the simulation of different types of AVs and compares the calibrated values in the literature with default values introduced in the recent version of PTV Vissim. In the present paper, the reviewed studies are partitioned into two main categories according to the characteristics of the studied AVs, the studies focused on autonomous automated vehicles (AAVs) and the ones focused on cooperative automated vehicles (CAVs). Our findings indicate that the literature expects a lower value for parameters including standstill distance (CC0), headway time (CC1), following variation (CC2), the threshold for entering "following" (CC3), negative/positive following thresholds (CC4/CC5), speed dependency of oscillation (CC6), oscillation acceleration (CC7), safety distance reduction factor (SDRF), and minimum headway front/rear (MinHW) for AVs than conventional vehicles (CVs). Besides, the literature expects higher values for parameters including standstill acceleration (CC8), acceleration at 80 km/h (CC9), looking distances, and maximum deceleration for cooperative braking (MaxDCB) for AVs. When cautious AVs are introduced, deterring effects are expected in the literature (e.g., higher CC0). Moreover, CAVs can have higher looking distance values compared with AAVs.
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| 2. |
- Beza, Abebe Dress, et al.
(författare)
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Impacts of Different Types of Automated Vehicles on Traffic Flow Characteristics and Emissions : A Microscopic Traffic Simulation of Different Freeway Segments
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 15:18
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Tidskriftsartikel (refereegranskat)abstract
- Different types of automated vehicles (AVs) have emerged promptly in recent years, each of which might have different potential impacts on traffic flow and emissions. In this paper, the impacts of autonomous automated vehicles (AAVs) and cooperative automated vehicles (CAVs) on capacity, average traffic speed, average travel time per vehicle, and average delay per vehicle, as well as traffic emissions such as carbon dioxide (CO2), nitrogen oxides (NOx), and particulate matter (PM10) have been investigated through a microsimulation study in VISSIM. Moreover, the moderating effects of different AV market penetration, and different freeway segments on AV's impacts have been studied. The simulation results show that CAVs have a higher impact on capacity improvement regardless of the type of freeway segment. Compared to other scenarios, CAVs at 100% market penetration in basic freeway segments have a greater capacity improvement than AAVs. Furthermore, merging, diverging, and weaving segments showed a moderating effect on capacity improvements, particularly on CAVs' impact, with merging and weaving having the highest moderating effect on CAVs' capacity improvement potential. Taking average delay per vehicle, average traffic speed, and average travel time per vehicle into account, simulation results were diverse across the investigated scenarios. The emission estimation results show that 100% AAV scenarios had the best performance in emission reductions in basic freeway and merging sections, while other scenarios increased emissions in diverging and weaving sections.
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| 3. |
- Fröidh, Oskar, et al.
(författare)
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Optimerade körtider med upphandlad och kommersiell persontrafik på samma bana
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 160-161
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Det är ganska vanligt att en tidtabell för en järnvägslinje innehåller olika tågsystem med varierande körtider. Det beror på olika marknadsförutsättningar, som olika trafikslag (ofta godståg och persontrafik med regionaltåg och snabbtåg) med olika upphållsmönster och fordon med olika topphastigheter. Samexistensen av olika körtider på en järnvägslinje minskar det totala antalet tåg som kan trafikera linjen jämfört med situationen där endast de snabbare tågen trafikerar nätet, och kapacitetsförlusten minskar nyttorna av tågtrafiken. Det finns därför ett behov av metoder att generera välfärdsoptimerade tidtabellslösningar vid blandade marknader med olika körtider.I litteraturen finns exempel på förbättrad kapacitetsallokering genom olika prissättningsmekanismer, som knapphetsprissättning, reservationspris och auktionering. De studerade lösningarna är antingen komplexa, vilket gör det svårt att implementera dem, eller kan endast tillämpas i lokala fall till exempel upphandlad tågtrafik som måste ge plats för kommersiell tågtrafik. Vårt syfte är följaktligen att försöka tillhandahålla lösningar som förbättrar kapacitetsallokering i tidtabellen vid blandade marknader på ett välfärdsoptimalt sätt. Projektet fokuserar på persontrafik med upphandlad (regional) och snabbare kommersiell tågtrafik på samma bana.I detta forskningsprojekt försöker vi svara på följande forskningsfrågor:Vilka är de bakomliggande drivkrafterna bakom operatörernas beteende för att utforma sitt utbud på blandade järnvägsmarknader?Hur skulle en möjlig körtidsreglering (till exempel reglering av minsta tillåtna körtid för tåglägen) påverka kapaciteten och utbudet vid en blandad marknad?Vilken skulle vara den optimala körtidsregleringen (det vill säga välfärdsmaximering) som skulle ge det för samhället mest fördelaktiga utnyttjandet av banans kapacitet?För att ta itu med de ovan nämnda forskningsfrågorna utvecklade vi kapslade logitmodeller, som syftar till att fånga resenärers beteende givet utbudet (till exempel restid, biljettpris, avgång) och infogade det i ett vinstmaximeringsproblem för att studera vinstmaximerande beteende hos kommersiella operatörer på en blandad marknad. Därefter formulerades ett problem med minsta körtid som syftar till att minska hastigheten på kommersiella tåg samtidigt som man studerar kommersiella operatörers beteende och dess effekt på kapaciteten. Slutligen formulerar vi ett välfärdsmaximeringsproblem för att undersöka den optimala körtiden och dess inverkan på efterfrågan (kommersiell och upphandlad tågtrafik) och kapacitet.
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| 4. |
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| 5. |
- Zefreh, Mohammad Maghrour, et al.
(författare)
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A data-driven decision support tool for public transport service analysis and provision
- 2023
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Ingår i: Transport Policy. - : Elsevier BV. - 0967-070X .- 1879-310X. ; 135, s. 82-90
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Tidskriftsartikel (refereegranskat)abstract
- Public transport service (PTS) analysis and provision is an important and challenging issue for public transport agencies. The results of the PTS analysis help transport planners to identify the areas in need of PTS improvement. Furthermore, relevant policy actions need to be determined for service provision to reach the desired level of PTS improvement in the identified areas. Without an appropriate decision support tool, planners need to apply several blind trials to find a policy action which improves the PTS in the examined areas. This paper introduces a data-driven decision support tool for PTS analysis and provision. The proposed framework combines a potentially large number of PTS measures while taking the correlation among the investigated measures into account and develops high-dimensional supervised classification models that predict the PTS levels for different policy actions. With this approach, planners can identify and prioritize the areas in need of PTS improvement, determine what policy actions should be targeted to improve the PTS in the identified areas, and predict the PTS impacts of these policy actions in the examined areas. The application of the proposed framework is demonstrated in detail through a case study of Budapest, Hungary, which is followed by a hypothetical policy implementation. The results show that mostly outskirts are in need of PTS improvement. Furthermore, the underlying reasons behind the areas with poor overall PTS are studied to target the relevant policy actions that improve the PTS in the identified areas. The PTS impacts of the targeted policy actions are studied by using the developed high-dimensional supervised classification models.
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| 6. |
- Zefreh, Mohammad Maghrour, et al.
(författare)
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Detecting metro service disruptions and predicting their network-wide domino effects using large-scale vehicle location data
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 104-105
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Disruptions in public transport have significant consequences for service users and providers. These include longer travel times, increased crowding, and a negative perception of the service among travelers. Therefore, it is essential to maintain the regularity of public transport services to ensure high-quality service. Regularity is measured by how closely the actual service adheres to the planned schedule. However, disruptions and minor disturbances constantly pose a threat to this regularity. To improve the reliability of public transport systems, operators need detailed information about disruptions, including their locations, timing, duration, and their network-wide domino effects. This information helps in developing effective recovery plans and providing real-time updates for passengers. Thus, quantifying and minimizing the impacts of disruptions is crucial for both users and service providers, as it directly affects passenger satisfaction and service provider revenues. To this end, the current research proposes an analytical framework for the automated detection of disruptions in metro services (i.e., primary delays) and prediction of their propagation effects (i.e., the trains and stations that will be affected and the extent of the impact) on the entire metro network (i.e., secondary delays). The proposed framework involves overlaying real-time vehicle locations (using AVL data) onto the scheduled train paths (obtained by transforming the static GTFS data into GPS-like data and incorporating day-time-trip-station-dependent dwell times computed using AVL data), thereby identifying deviations from the scheduled train paths. Additionally, a graph modeling framework is proposed to represent the interdependencies between trains and stations in the metro network. In this graph model, running time, dwell time, and headways are depicted as edges, while stations are represented as nodes. A backward pass algorithm is developed to identify the main causes of the observed station delays. After identifying the time-stamped positions of the primary delays, a forward pass algorithm is developed to establish an association between the detected primary delays and their network-wide consequences, resulting in a primary-secondary dataset. The acquired primary-secondary dataset is enriched with additional features (e.g., timetable slacks) and fed into a deep learning architecture to predict network-wide secondary delays following the identification of any service disruptions within the metro system.
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| 7. |
- Zefreh, Mohammad Maghrour, et al.
(författare)
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Intention to use private autonomous vehicles in developed and developing countries : What are the differences among the influential factors, mediators, and moderators?
- 2023
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Ingår i: Travel Behaviour & Society. - : Elsevier BV. - 2214-367X .- 2214-3688. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the intention to use private autonomous vehicles (PAVs) in developed (i.e., the United States, Belgium, the United Kingdom, Italy, Portugal, and Hungary) and developing countries (i.e., Egypt, Iraq, Jordan, Lebanon, and Saudi Arabia). Self-efficacy, the attitude toward using PAV technology, and the trust in PAV constructs are integrated into an extended Unified Theory of Acceptance and Use of Technology (UTAUT2) model to increase the understanding of users' perceptions of PAVs in developed and developing countries. The results of partial least squares structural equation modeling show the attitude toward using PAV technology to be the strongest predictor of the intention to use PAVs in developed and developing countries. Performance expectancy and trust in PAV are the strongest predictors of attitude toward using PAV technology in developed and developing countries, respectively. Effort-related constructs (i.e., effort expectancy and self-efficacy) do not directly affect the behavioral intention of the respondents from the developed countries while significantly affecting the behavioral intention of the respondents from the developing countries. The results of the mediation analysis show that the relationship between effort expectancy and behavioral intention is fully mediated by the attitude toward using PAV technology and performance expectancy for the respondents of the developed countries. Furthermore, the results of the multi-group moderation analysis show the relationship between performance expectancy and behavioral intention as well as social influence and the trust in PAV is not moderated by any of the moderators (i.e., age, gender, educational level, employment status, income level, car ownership status, and driving license status), neither for the developed countries nor for the developing countries.
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| 8. |
- Zefreh, Mohammad Maghrour, et al.
(författare)
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Understanding the antecedents of hedonic motivation in autonomous vehicle technology acceptance domain : A cross-country analysis
- 2023
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Ingår i: Technology in society. - : Elsevier BV. - 0160-791X .- 1879-3274. ; 74
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Tidskriftsartikel (refereegranskat)abstract
- The literature on autonomous vehicle (AV) acceptance highlights the significance of hedonic motivation in AV adoption. Numerous studies empirically confirm hedonic motivation as either the most or one of the most influential factors in the acceptance of AV. This fact calls for a need to achieve a wider understanding of the potential AV users’ perceived enjoyment (i.e., hedonic motivation). To this end, this study investigates the antecedents of hedonic motivation in the AV technology acceptance domain. The partial least square structural equations modeling approach was applied to analyze the data collected from 1823 respondents from 11 countries via an online survey. The developed hypotheses are examined for the entire sample, as well as separately for the Global North (GN) countries' sample, Global South (GS) countries' sample, and each individual country through a cross-country analysis. The results for the entire sample indicate that social influence is the strongest predictor of hedonic motivation, consistent with the findings of the GN sample. However, in the GS sample, self-efficacy emerges as the strongest predictor of hedonic motivation. Perceived safety is the second strongest predictor of hedonic motivation for both the GN and GS samples, highlighting its importance in relation to the perceived enjoyment of PAV. Trust does not significantly contribute to hedonic motivation, while the enjoyment of driving conventional cars has a small negative impact on hedonic motivation in the GS sample. The cross-country analysis reveals general patterns in the findings of the GN and GS samples, while highlighting a few exceptions. The results of the multi-group moderation analysis highlight the significant impact of the respondents' geographical distribution (GN vs GS) on their perceived enjoyment of PAV. Additionally, the analysis indicates that female respondents who enjoy driving conventional cars are less likely to perceive PAV as enjoyable compared to male participants who enjoy driving conventional cars.
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