| 1. |
- Jenelius, Erik, Docent, 1980-, et al.
(författare)
-
Dynamiska trängselindex
- 2017
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Under det senaste decenniet har nya datakällor, så som GPS‐data från taxibilar och storskaliga system av fasta detektorer, gett betydligt större möjligheter att kartlägga hur trängseln varierar i en stad, d.v.s. variation mellan gator och områden, olika tidpunkter på dagen och mellan olika månader eller år.På den teoretiska sidan har det, under ungefär samma tidsperiod, upptäckts ett samband mellan fordonstäthet och hastighet på områdesnivå, vilket kallas det makroskopiska fundamentaldiagrammet (MFD). Tidigare har detta samband uppmätts på länknivå och kallas då fundamentaldiagram (FD). MFD kopplar samman antalet fordon i ett område med den genomsnittliga hastigheten ellerflödet i området. Man har också visat att MFD under ideala förhållanden är enegenskap hos nätverket i sig (infrastruktur och trafikstyrning), d.v.s. det beror inte på efterfrågan.I denna rapport använder vi dessa nya trafikmätningsmetoder och teoretiska framsteg inom MFD för två syften. För det första beskriver vi hur trängseln varierar över dagen på Södermalm och i City‐området i Stockholm genom att titta på MFD från empiriska datakällor så som GPS‐data från taxi‐bilar, slangmätningar och restidskameror. För det andra jämför vi simulerat MFD för City‐området med empiriskt MFD för samma område. Detta för att validera hurväl City‐modellen framtagen med simuleringsverktyget Transmodeler kan återskapa trängselsituationen på områdesnivå.Rapporten visar att väldefinierade MFD existerar både för Södermalm och Cityområdet.MFD visar att hastigheten sjunker och fordonstätheten ökar undermorgonens och eftermiddagens rusningstimmar, men trängselnivåerna når inte den punkt där flödet börjar avta trots att fordonstätheten ökar (hyperträngsel). Det är således trångt i innerstaden under rusningstimmarna, men kapaciteten i nätverket räcker ändå till. De två stora lederna Stadsgårdsleden och Sveavägen visar dock tecken på hyperträngsel om fundamentaldiagram skapas separat för dessa leder.Vidare visar rapporten att MFD har stor potential som verktyg för att valideraen simuleringsmodell. I rapporten jämförs MFD från City‐området i Transmodeler med empirisk MFD för samma område. Simuleringsmodellen överskattar flöde och hastighet vid låg densitet. Vid hög densitet ändras dockbilden och simuleringsresultaten underskattar flöde och hastighet. Det verkarsom att kapaciteten i nätverket underskattas, vilket ger högre trängsel imodellen än i mätdata. MFD från Transmodeller visar lägre flöden underavvecklingen av rusningen än under uppbyggnaden, både under förmiddag och eftermiddag, vilket inte syns i de empiriska data. Detta tyder på att det finns stora kö‐problem i simuleringsmodellen, vilket man inte ser tecken på i empiriskt MFD.
|
|
| 2. |
|
|
| 3. |
- Jenelius, Erik, 1980-, et al.
(författare)
-
Validation of Traffic Simulation Models Based on the Macroscopic Fundamental Diagram
- 2017
-
Ingår i: Transportation Research Procedia. - : Elsevier. - 2352-1465. ; , s. 561-568
-
Konferensbidrag (refereegranskat)abstract
- Urban traffic simulation models could benefit significantly from new validation methods with potential to reduce the time-consuming calibration and validation work needed before application of the model to evaluate city infrastructure or policy implementations. Current practice is to validate simulation models locally through comparison with point flow measurements and travel times on some important routes. However, for many applications, the level of congestion in an entire area is important. During the last decade, several studies have found empirical evidence of a relation between flow and density on city district level, the existence of a so-called macroscopic fundamental diagram (MFD). This paper shows how the MFD can be used to validate results from a traffic simulation model for a city district. Furthermore, the paper shows empirical results for Stockholm, Sweden. © 2017 The Authors. Published by Elsevier B.V.
|
|
| 4. |
|
|
| 5. |
- Cats, Oded, 1983-, et al.
(författare)
-
How fair is the fare? Estimating travel patterns and the impacts of fare schemes for different user groups in Stockholm based on smartcard data : Final report for Trafik och Region 2018 SLL-KTH research project
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- There is a rapid increase in the deployment, acquisition and analysis of automated fare collection (AFC) systems, enabling a profound change in the ability to analyze high-volume data that relate to observed passenger travel behavior and recurrent patterns. The analysis of such passively collected data offers direct access to a continuous flow of observed passenger behavior at a large scale, saving expensive data collection efforts. For a review of the spectrum of applications – from strategic demand estimation to operational service performance measurements.The FairAccess project leverages on the availability of Access-kort data for the vast majority of trips performed in Stockholm County. The overarching goal of this project is to develop means to analyse empirically the impacts of policy/planning measures based on disaggregate passively collected smart card data. This involves a series of analysis and modelling challenges. We develop and apply a series algorithms to infer of tap-out locations, infer vehicles and travel times, and infer transfers to that journeys can be composed. Tap-in records have been matched with corresponding inferred tap-out locations and time stamps for about 80% of all records. Thereafter, we construct time-dependent origin-destination matrices for which segmentations can be performed with respect to geographical and user product features.We demonstrate the approach and algorithms developed by performing a before-after analysis of the fare scheme change from zone-based to flat fares. We analyse changes in travel patterns and derive price elasticities for distinctive market segments. The introduced fare policy delivered the desirable result of an increased ridership through improved convenience of the single-use products. Nevertheless, the significance of the service convenience component was underestimated, which resulted in the price adjustments being not in line with the mobility effects.The planning and development of the Stockholm public transport system must rely on the best empirical foundations available to support evidence-based decision-making and make the right priorities. To this end, the development and analysis performed in the FairAccess project lay a necessary foundation for further methodological developments and analyses such as on-board crowding evaluation, demand forecasting and identifying user groups.
|
|
| 6. |
- Cebecauer, Matej, et al.
(författare)
-
3D Speed Maps and Mean Observations Vectors for Short-Term Urban Traffic Prediction
- 2019
-
Ingår i: TRB Annual Meeting Online. - Washington DC, US. ; , s. 1-20, s. 1-20
-
Konferensbidrag (refereegranskat)abstract
- City-wide travel time prediction in real-time is an important enabler for efficient use of the road network. It can be used in traveler information to enable more efficient routing of individual vehicles as well as decision support for traffic management applications such as directed information campaigns or incident management. 3D speed maps have been shown to be a promising methodology for revealing day-to-day regularities of city-level travel times and possibly also for short-term prediction. In this paper, we aim to further evaluate and benchmark the use of 3D speed maps for short-term travel time prediction and to enable scenario-based evaluation of traffic management actions we also evaluate the framework for traffic flow prediction. The 3D speed map methodology is adapted to short-term prediction and benchmarked against historical mean as well as against Probabilistic Principal Component Analysis (PPCA). The benchmarking and analysis are made using one year of travel time and traffic flow data for the city of Stockholm, Sweden. The result of the case study shows very promising results of the 3D speed map methodology for short-term prediction of both travel times and traffic flows. The modified version of the 3D speed map prediction outperforms the historical mean prediction as well as the PPCA method. Further work includes an extended evaluation of the method for different conditions in terms of underlying sensor infrastructure, preprocessing and spatio-temporal aggregation as well as benchmarking against other prediction methods.
|
|
| 7. |
- Cebecauer, Matej, et al.
(författare)
-
Real-time city-level traffic prediction in the context of Stockholm City
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: The ongoing POST (Prediktions- och Scenariobaserad Trafikledning) project and the previous project Mobile Millennium Stockholm (MMS) provided tools and frameworks for real-time estimation and prediction of travel times on the city-level. City-level prediction of the traffic state as well as the traffic demand is important for both traveler information applications, such as online navigation, and traffic management applications, such as scenario evaluation of incident management strategies. However, city-level prediction is very challenging and requires efficient processing of large amounts of data. Here we present the recent research about effects of the clustering on the prediction performance and computational cost. Partitioning of the road network based on spatial and temporal attributes can potentially result in clusters that provide more robust and accurate prediction with reasonable bias-variance tradeoff. Methods: The effects of the clustering on the prediction performance are studied on the three case studies, representing different travel time sources in Stockholm city. First represent 15 MCS radars as the sources of travel times. Second 420 segments on the major roads around Stockholm with travel times estimated from the MCS radars. Third, travel times of 11,340 links processed from GPS data of 1,500 taxis operating in Stockholm. With the computational experiments, we studied different clustering approaches based on the day classification, functional classes, spatial locations and temporal attributes, and how they can effect the prediction performance and computational cost.Results: reveal that partitioning can significantly improve the prediction accuracy and rapidly decrease the computational cost and time.
|
|
| 8. |
- Cebecauer, Matej, 1986-
(författare)
-
Short-Term Traffic Prediction in Large-Scale Urban Networks
- 2019
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- City-wide travel time prediction in real-time is an important enabler for efficient use of the road network. It can be used in traveler information to enable more efficient routing of individual vehicles as well as decision support for traffic management applications such as directed information campaigns or incident management. 3D speed maps have been shown to be a promising methodology for revealing day-to-day regularities of city-level travel times and possibly also for short-term prediction. In this paper, we aim to further evaluate and benchmark the use of 3D speed maps for short-term travel time prediction and to enable scenario-based evaluation of traffic management actions we also evaluate the framework for traffic flow prediction. The 3D speed map methodology is adapted to short-term prediction and benchmarked against historical mean as well as against Probabilistic Principal Component Analysis (PPCA). The benchmarking and analysis are made using one year of travel time and traffic flow data for the city of Stockholm, Sweden. The result of the case study shows very promising results of the 3D speed map methodology for short-term prediction of both travel times and traffic flows. The modified version of the 3D speed map prediction outperforms the historical mean prediction as well as the PPCA method. Further work includes an extended evaluation of the method for different conditions in terms of underlying sensor infrastructure, preprocessing and spatio-temporal aggregation as well as benchmarking against other prediction methods.
|
|
| 9. |
- Cebecauer, Matej, et al.
(författare)
-
Spatio-Temporal Partitioning of Large Urban Networks for Travel Time Prediction
- 2018
-
Ingår i: 2018 21ST INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC). - : IEEE. - 9781728103235 ; , s. 1390-1395
-
Konferensbidrag (refereegranskat)abstract
- The paper explores the potential of spatiotemporal network partitioning for travel time prediction accuracy and computational costs in the context of large-scale urban road networks (including motorways/freeways, arterials and urban streets). Forecasting in this context is challenging due to the complexity, heterogeneity, noisy data, unexpected events and the size of the traffic network. The proposed spatio-temporal network partitioning methodology is versatile, and can be applied for any source of travel time data and multivariate travel time prediction method. A case study of Stockholm, Sweden considers a network exceeding 11,000 links and uses taxi probe data as the source of travel times data. To predict the travel times the Probabilistic Principal Component Analysis (PPCA) is used. Results show that the spatio-temporal network partitioning provides a more appropriate bias-variance tradeoff, and that prediction accuracy and computational costs are improved by considering the proper number of clusters towards robust large-scale travel time prediction.
|
|
| 10. |
- Ding-Mastera, Jing, et al.
(författare)
-
A latent-class adaptive routing choice model in stochastic time-dependent networks
- 2019
-
Ingår i: Transportation Research Part B. - : Elsevier. - 0191-2615 .- 1879-2367. ; 124, s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- Transportation networks are inherently uncertain due to random disruptions; meanwhile, real-time information potentially helps travelers adapt to realized traffic conditions and make better route choices under such disruptions. Modeling adaptive route choice behavior is essential in evaluating real-time traveler information systems and related policies. This research contributes to the state of the art by developing a latent-class routing policy choice model in a stochastic time-dependent network with revealed preference data. A routing policy is defined as a decision rule applied at each link that maps possible realized traffic conditions to decisions on the link to take next. It represents a traveler's ability to look ahead in order to incorporate real-time information not yet available at the time of decision. A case study is conducted in Stockholm, Sweden and data for the stochastic time-dependent network are generated from hired taxi Global Positioning System (GPS) readings. A latent-class Policy Size Logit model is specified, with routing policy users who follow routing policies and path users who follow fixed paths. Two additional layers of latency in the measurement equation are accounted for: 1) the choice of a routing policy is latent and only its realized path on a given day can be observed; and 2) when GPS readings have relatively long gaps, the realized path cannot be uniquely identified, and the likelihood of observing vehicle traces with non-consecutive links is instead maximized. Routing policy choice set generation is based on the generalization of path choice set generation methods. The generated choice sets achieve 95% coverage for 100% overlap threshold after correcting GPS mistakes and breaking up trips with intermediate stops, and further achieve 100% coverage for 90% overlap threshold. Estimation results show that the routing policy user class probability increases with trip length, and the latent-class routing policy choice model fits the data better than a single-class path choice or routing policy choice model. This suggests that travelers are heterogeneous in terms of their ability and/or willingness to plan ahead and utilize real-time information, and an appropriate route choice model for uncertain networks should take into account the underlying stochastic travel times and structured traveler heterogeneity in terms of real-time information utilization.
|
|
| 11. |
- Fu, Jiali, et al.
(författare)
-
Identification of workstations in earthwork operations from vehicle GPS data
- 2017
-
Ingår i: Automation in Construction. - : ELSEVIER SCIENCE BV. - 0926-5805 .- 1872-7891. ; 83, s. 237-246
-
Tidskriftsartikel (refereegranskat)abstract
- The paper proposes a methodology for the identification of workstations in earthwork operations based on GPS traces from construction vehicles. The model incorporates relevant information extracted from the GPS data to infer locations of different workstations as probability distributions over the environment. Monitoring of workstation locations may support map inference for generating and continuously updating the layout and road network topology of the construction environment. A case study is conducted at a complex earthwork site in Sweden. The workstation identification methodology is used to infer the locations of loading stations based on vehicle speeds and interactions between vehicles, and the locations of dumping stations based on vehicle turning patterns. The results show that the proposed method is able to identify workstations in the earthwork environment efficiently and in sufficient detail.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
- Hatzenbühler, Jonas, et al.
(författare)
-
Determining the optimal allocation of automated buses on a public transport network
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: This research is driven by the general need for affordable, frequent and convenient Public Transport (PT) solutions. Over the last years the advances in the sector of autonomous systems have triggered studies on their effect on PT. AB lower the operational costs due to the removal of labor costs, which in developed countries account for more than half of the overall operational costs. These lower operational costs are expected to lead to higher service frequencies. The introduction of more diverse vehicle sizes is then possible and economical which will allow the operators to target the user demand better than with a fixed sized vehicle fleet. In this we analyse the use of AB systems in existing PT networks by:- define an AV specific objective function- integrate AV systems in a mesoscopic simulation framework- extract KPIs for the economic deployment of AB systems This study aims at answering the following research questions:- How can AB systems be used to improve passenger and operator costs on existing lines?- What are the implications of the cost trade off in terms of the defined KPI?- On which lines is the deployment of AB systems most interesting in terms of social welfare?Methods: The implementation of the framework adopts a simulation based optimization approach. The multi-agent simulation software (BusMezzo) uses the networks routes and the decision variables as input values. Subsequently the simulation is executed, and the filtered results will be handed to the Genetic Algorithm optimization. The objective function minimizes the overall cost which is the sum of operator costs (capital costs & operation cost) and user cost (travel time, waiting time, ticket cost,..). This loop is executed until convergence. The decision variables for the optimization module are the vehicle capacity, the frequency per route and the vehicle type. For validation of the optimization approach described above a brute force analysis is done on the synthetic Network provided by Spiess & Florian. In the brute force analysis the entire solution space for the network is displayed and can be analyzed. This allows for deeper understanding of the underlying processes and validates the optimization results. With the knowledge of this approach the optimization parameters are configured.Results: The proposed model was applied to a on-going pilot case study in the area of Kista in Stockholm. The proposed model is generally applicability for larger scale problems. Possible applications of the proposed methodology are:- tool for identifying the most promising areas for introducing AB- measurement for the economic impact of AB Systems on PT- the design of the network for a mixed operationPotential extensions of the model include the fleet composition and fleet size per line of special AB zones in high user demand areas.The main results and conclusions are:- Frequency and Capacity have comparable impact on total cost- Introducing Autonomous Vehicle on high demand lines is beneficial- There are "sweet spots" for operating for operating vehicle mixes- some configurations are only profitably operable with autonomous vehicle
|
|
| 16. |
|
|
| 17. |
- Jenelius, Erik, Docent, 1980-
(författare)
-
Att prediktera trängseln i bussar och tunnelbana
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: I takt med att städerna växer, upplever många kollektivtrafiksystem ökat trängsel. Trängsel i fordon kan ha många negativa effekter på resenärens nöjdhet och välbefinnande, inklusive stress, ångest, hot mot personlig säkerhet och produktivitetstapp på grund av brist på sittplats. Studier visar att trängsel kan öka resenärernas värde av tidsbesparingar avsevärt. Trängsel påverkar också fordonets uppehållstider vid stationer, vilket i sin tur minskar tillförlitligheten. Beläggningen kan vara mycket ojämnt fördelad mellan bussar och mellan tågvagnar även under rusningsperioden. Det innebär att den effektiva kapaciteten är betydligt lägre än den nominella kapaciteten baserat på att alla fordon och vagnar används lika. Följaktligen krävs fler fordon än vad som krävs för att betjäna efterfrågan, vilket leder till betydande kostnader för operatören. Ojämn passagerarspridning mellan fordonsenheter innebär också att den genomsnittliga upplevda trängselnivån per passagerare är högre än om passagerarna är jämnt fördelade. Under de senaste åren har många städer börjat tillhandahålla realtidsinformation om ankomsttider vid hållplatser eller i mobila applikationer. Realtidsinformation om ankomsttider har i flera studier visats ha positiva effekter på upplevda väntetider, säkerhet och generell nöjdhet. System som tillhandahåller realtidsinformation om trängsel i ankommande fordon är mindre vanliga i praktiken. I teorin tillåter informationen resenärer att fatta bättre informerade beslut om huruvida man ska gå ombord på ett fordon eller inte baserat på deras preferenser för trängsel, väntetid, total restid osv. Således kan trängselinformation I realtid öka passagerarnas nöjdhet och resekvalitet, vilket skulle vara attraktivt för kollektivtrafikmyndigheter och operatörer.Methods: Att tillhandahålla trängselinformation kräver generellt att passagerarbelastningar predikteras flera stationer framåt från de nuvarande positionerna. Syftet med den här presentationen är att formulera problemet att prediktera trängseln i bussar och tåg baserat på realtidsbelastningsdata och utvärdera prestandan hos flera prediktionsmetoder (stegvis regression, lasso och boosted tree ensembles). Problemet studeras för flera målstationer längs busslinje 4 och röd tunnelbanelinje i Stockholm. Prediktionsnoggrannheten utvärderas med hänsyn till absoluta passagerbelastningar samt fördefinierade diskreta trängningsnivåer.Results: Resultaten visar att realtidsinformation om beläggningsgrader gör att framtida trängsel kan predikteras betydligt mer exakt än om bara historiska data finns tillgängliga. Effekten är särskilt stor för stationer/hållplatser och tider på dagen med hög belastning. Precisionen ökar ju närmare det aktuella fordonen kommer målstationen/hållplatsen. De olika prediktionsmetoderna ger alla liknande resultat.
|
|
| 18. |
- Jenelius, Erik, 1980-
(författare)
-
Car-Specific Metro Train Crowding Prediction Based on Real-Time Load Data
- 2018
-
Ingår i: 2018 21ST INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC). - : IEEE. - 9781728103235 ; , s. 78-83
-
Konferensbidrag (refereegranskat)abstract
- The paper formulates the car-specific metro train crowding prediction problem based on real-time load data and evaluates the performance of several prediction methods (stepwise regression, lasso, and boosted tree ensembles). The problem is studied for multiple stations along a metro line in Stockholm, Sweden. Prediction accuracy is evaluated with respect to absolute passenger loads and predefined discrete crowding levels. When available, predictions with real-time load data significantly outperform historical averages, with accuracy improvements varying in magnitude across target stations and prediction horizons.
|
|
| 19. |
- Jenelius, Erik, Docent, 1980-
(författare)
-
Data-driven bus crowding prediction based on real-time passenger counts and vehicle locations
- 2019
-
Konferensbidrag (refereegranskat)abstract
- The paper addresses the bus crowding prediction problem based on real-time vehicle location and passenger count data and evaluates the performance of a data-driven lasso regression prediction method. The problem is studied for a high-frequency bus line in Stockholm, Sweden. Prediction accuracy is evaluated with respect to absolute passenger loads and predefined discrete crowding levels. When available, predictions with real-time vehicle location and, in particular, passenger count data significantly outperform predictions based only on historical data, with accuracy improvements varying in magnitude across target stations and prediction horizons.
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
- Jenelius, Erik, 1980-
(författare)
-
Public transport experienced service reliability : Integrating travel time and travel conditions
- 2018
-
Ingår i: Transportation Research Part A. - : Elsevier. - 0965-8564 .- 1879-2375. ; 117, s. 275-291
-
Tidskriftsartikel (refereegranskat)abstract
- The paper proposes a generalization of public transport service reliability, incorporating both travel times and travel conditions based on passengers’ perceived journey time. Time is partitioned into waiting and transfer time as well as in-vehicle time under different travel conditions (crowding and seat availability), which may vary along a journey and between days. The experienced service reliability gap (ESRG) index is introduced, defined as the difference between an upper percentile (e.g., the 95th) and the median perceived journey time across days for a particular OD pair and departure time. The metric is evaluated by tracing virtual trips from origin to destination with journey times and travel conditions based on automated vehicle location (AVL) and automated passenger count (APC) data and seated status modelled probabilistically. A study of a high-frequency bus line in Stockholm, Sweden shows that travel conditions co-vary only weakly with nominal journey time, and the ESRG index display patterns across the day not evident in existing reliability measures, such as a wider and later afternoon peak. The ESRG displays significant variation between OD pairs along the line. Correlation with headway variability suggests that measures improving bus regularity have additional positive effects on experienced service reliability.
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
- Laskaris, Georgios, et al.
(författare)
-
Multiline holding based control for lines merging to a shared transit corridor
- 2019
-
Ingår i: Transportmetrica B. - : Taylor & Francis. - 2168-0566. ; 7:1, s. 1062-1095
-
Tidskriftsartikel (refereegranskat)abstract
- 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 consistent network-wide travel time benefits.
|
|
| 27. |
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
- Leffler, David, et al.
(författare)
-
Utvärdering av delade självkörande fordon inom efterfrågestyrd kollektivtrafik genom simulering
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Bakgrund: Det finns påståenden om att genom användning av delade självkörande fordon inom flexibel-, eller efterfrågestyrd kollektivtrafik (EKT) skulle man kunna förbättra mobiliteten för personer med begränsad tillgång till en privat bil och för personer utan adekvat tillgång till högkapacitets kollektivtrafik. Oavsett om det är automatiserat eller inte, så är dock kostnadseffektiviteten och servicenivån som förses en passagerare av en EKT-flotta starkt beroende av förmågan att effektivt kunna matcha fordon till passagerarbegäran i realtid. Vidare kan flexibla rutter och tidtabeller öka osäkerheten om förväntade väntetider och restider för passagerare i förhållande till en traditionell tjänst med fast tidtabell och rutt. Den uppfattade tillförlitligheten hos tjänsten kan i sin tur kraftigt påverka en resenärs val av rutt och transportmedel när det finns tillgång till andra alternativ, vilket i sin tur bidrar till osäkerheten i uppskattningar av framtida efterfrågan när den matchas till EK-flottan i realtid.Metoder: Även om självkörande fordon utvecklas i hög takt, har de fortfarande inte uppnått nivåer av automatisering och säkerhet som möjliggör att de används i bredare tillämpningar. EKT-system är också svåra att pröva, på grund av höga implementeringskostnader samt osäkerheten i efterfrågan som resulterar från varierande design och strategier för hur EKT-flottan samordnas. Simulering är således ett viktigt verktyg för att utvärdera självkörande fordon inom EKT. För att simulera EKT utvecklades en justerbar modell för att dynamiskt matcha delade fordon till stokastiskt genererade passageraranrop. Denna modell integrerades sedan med en simuleringsmodell för kollektivtrafik som representerar både trafikdynamik samt inlärning och adaptering av individuella passagerare.Resultat: Med detta ramverk kan vi bättre studera interaktionen mellan operativa egenskaper av en EKT-tjänst och dess resulterande effekter på en resenärs val av rutt, transportmedel och generaliserade kostnader. I denna presentation presenteras ramverket för att studera EKT samt en demonstration av dess tillämpning för att utvärdera en automatiserad EKT-tjänst som ett samexisterande alternativ till en traditionell kollektivtrafiktjänst med förutbestämd tidtabell och rutt.
|
|
| 31. |
- Mattsson, Lars-Göran, 1947-, et al.
(författare)
-
Transportsystemets sårbarhet och resiliens
- 2015
-
Ingår i: Slutrapport från Ramforskningsprogrammet PRIVAD. - Lund : Lunds universtitet. ; , s. 54-65
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 32. |
|
|
| 33. |
|
|
| 34. |
- Peftitsi, Soumela, et al.
(författare)
-
Modeling the interaction between metro platform and on-board crowding
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Many public transport station platforms are overcrowded during the peak periods which affects crowding inside the transit vehicle, especially when passengers are not uniformly distributed between individual car units.A methodology based on multiple automated data sources for identifying the factors that affect the distribution of boarding passengers in individual cars of a metro train is proposed. The methodology is applied to a case study for a sequence of stations in the Stockholm metro network. While train car loads are generally skewed towards the leading cars, results indicate that a crowded arriving train is associated with increasing boarding shares in the middle and rear cars. Moreover, higher platform crowding level leads to larger boarding share of the middle cars. These ndings suggest that passengers opt for less crowded trains in crowded situations, trading-off walking andcrowding while waiting and riding. We nd that the boarding car distribution is alsoa ected by the locations of platform access points and the distribution of entering traveler flows.To measure the unevenness of the crowding distribution among the cars of rail transit vehicle, a train crowding unevenness metric is introduced. It is defined as the total experienced crowding across all possible distributions of the same total train load. The methodology is demonstrated for the metro network in Stockholm, Sweden based on automated car load data. Train crowding unevenness is found to be lower at departure from inner city metro stations and especially during the highest peak of the morning rush hour; this finding suggests that the uneven distribution of passengers in the trainis critically affected by the total passenger load inside the vehicle. Investigating this interaction, we found that train crowding evenness increases with the on-board passenger load. Certain metro stops are exceptions to the aforementioned finding which could be explained by the existence of a popular or a single station access point that leads to skewed distribution of passengers on the platform prior the arrival of the train.Finally, a method to evaluate and forecast crowding in individual car units by using a dynamic and stochastic transit assignment model is developed. The validity of the model and its sensitivity to the valuation of walking time has been examined. It is found that the model reproduces the average car load shares when the walking time is valued higher, and specifically 5 times higher than in-vehicle time. This finding suggests that passengers may value the walking time on the station platform higher than the walking time from/to the station. An intervention scenario has been evaluated, showing that if a second access point is added at Universitetet, the vehicle passenger distribution tends to be more even upon departure from Universitetet and the downstream stations; 3% of the average total vehicle load switches from the front train car to other cars upon train departure from Universitetet and Tekniska högskolan.The project insights may be used by transit planners and operators to increase the understanding of how passengers behave under crowding conditions, identify the factors that affect travelers' choice to board a specific metro car and eventually increase the capacity utilization of the trains through investments in infrastructure or operational interventions and thereby reduce the experienced on-board crowding level.
|
|
| 35. |
- Pernestål Brenden, Anna, 1978-, et al.
(författare)
-
Shared Automated Vehicles - Research & Assessment in a 1st pilot : SARA1 Results report
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The technological advance of automated vehicles (AV) is escalating as AVs are expected to have a great potentialto not only cut operation costs but also contribute to the service offered to users. Several pilots and initiatives areplanned in Sweden and especially within the Stockholm metropolitan area. The first is the pilot in Kista plannedby Nobina and involving two vehicles of the type Easy Mile EZ10. Nobina project to run automated bus in Kista,called “Autopiloten” project. SARA1 research project aimed at assessing Kista pilot from behavioural andsystemic perspectives in order to understand the effects and potential of AV:s for shared services. The results ofSARA1 project are important to not only evaluate these pilots from a technical perspective but also to startassessing societal, users and system perspectives Creating knowledge of valuable socio-economic factors intransition to autonomous. In the following we provide, a short description of Kista pilot operations provided byNobina, a state of the art, methods, results, and finally discussion and conclusions.
|
|
| 36. |
- Rahmani, Mahmood, 1977-, et al.
(författare)
-
Travel time estimation from sparse floating car data with consistent path inference : A fixed point approach
- 2017
-
Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 85, s. 628-643
-
Tidskriftsartikel (refereegranskat)abstract
- Estimation of urban network link travel times from sparse floating car data (FCD) usually needs pre-processing, mainly map-matching and path inference for finding the most likely vehicle paths that are consistent with reported locations. Path inference requires a priori assumptions about link travel times; using unrealistic initial link travel times can bias the travel time estimation and subsequent identification of shortest paths. Thus, the combination of path inference and travel time estimation is a joint problem. This paper investigates the sensitivity of estimated travel times, and proposes a fixed point formulation of the simultaneous path inference and travel time estimation problem. The methodology is applied in a case study to estimate travel times from taxi FCD in Stockholm, Sweden. The results show that standard fixed point iterations converge quickly to a solution where input and output travel times are consistent. The solution is robust under different initial travel times assumptions and data sizes. Validation against actual path travel time measurements from the Google API and an instrumented vehicle deployed for this purpose shows that the fixed point algorithm improves shortest path finding. The results highlight the importance of the joint solution of the path inference and travel time estimation problem, in particular for accurate path finding and route optimization.
|
|
| 37. |
- Saadallah, Amal, et al.
(författare)
-
BRIGHT - Drift-Aware Demand Predictions for Taxi Networks
- 2019
-
Ingår i: 2019 IEEE 35TH INTERNATIONAL CONFERENCE ON DATA ENGINEERING (ICDE 2019). - : IEEE. - 9781538674741 ; , s. 2145-2146
-
Konferensbidrag (refereegranskat)abstract
- The dynamic behavior of urban mobility patterns makes matching taxi supply with demand as one of the biggest challenges in this industry. Recently, the increasing availability of massive broadcast GPS data has encouraged the exploration of this issue under different perspectives. One possible solution is to build a data-driven real-time taxi-dispatching recommender system. However, existing systems are based on strong assumptions such as stationary demand distributions and finite training sets, which make them inadequate for modeling the dynamic nature of the network. In this paper, we propose BRIGHT: a drift-aware supervised learning framework which aims to provide accurate predictions for short-term horizon taxi demand quantities through a creative ensemble of time series analysis methods that handle distinct types of concept drift. A large experimental set-up which includes three real-world transportation networks and a synthetic test-bed with artificially inserted concept drifts, was employed to illustrate the advantages of BRIGHT when compared to S.o.A methods for this problem.
|
|
| 38. |
|
|
| 39. |
- Tympakianaki, Athina, et al.
(författare)
-
Anatomy of tunnel congestion : Causes and implications for tunnel traffic management
- 2019
-
Ingår i: Tunnelling and Underground Space Technology. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0886-7798 .- 1878-4364. ; 83, s. 498-508
-
Tidskriftsartikel (refereegranskat)abstract
- Tunnel congestion is an important safety problem and is often dealt with using disruptive traffic management strategies, such as closures. The paper proposes an approach to identify the underlying causes of recurrent congestion in tunnels and tests the hypothesis that the cause may vary from day to day. It also suggests that the appropriate tunnel management strategy to deploy depends on the cause. Utilizing traffic sensor data the approach consists of: (i) cluster analysis of historical traffic data to identify distinct congestion patterns; (ii) in-depth analysis of the underlying demand patterns and associated bottlenecks; (iii) simulation to evaluate alternative strategies for each demand pattern; (iv) on-line classification analysis which is able to identify, in real time, the emerging congestion pattern, and inform the type of mitigation strategy to be implemented. The methodology is demonstrated for a congested tunnel in Stockholm, Sweden revealing two different spatio-temporal congestion patterns. The results show that, if the current strategy of closures is to be used, the timing should depend on the congestion pattern. However, metering is the most promising strategy. The on-line classification of the emerging congestion pattern is effective and can inform appropriate strategy proactively. The analysis emphasizes that the effectiveness of tunnel traffic management can be increased by identifying the causes of congestion on a given day.
|
|
| 40. |
- Tympakianaki, Athina, et al.
(författare)
-
Impact analysis of transport network disruptions using multimodal data : A case study for tunnel closures in Stockholm
- 2018
-
Ingår i: Case Studies on Transport Policy. - : ELSEVIER SCIENCE BV. - 2213-624X .- 2213-6258. ; 6:2, s. 179-189
-
Tidskriftsartikel (refereegranskat)abstract
- The paper explores the utilization of heterogeneous data sources to analyze the multimodal impacts of transport network disruptions. A systematic data-driven approach is proposed for the analysis of impacts with respect to two aspects: (a) spatiotemporal network changes, and (b) multimodal effects. The feasibility and benefits of combining various data sources are demonstrated through a case study for a tunnel in Stockholm, Sweden which is often prone to closures. Several questions are addressed including the identification of impacted areas, and the evaluation of impacts on network performance, demand patterns and performance of the public transport system. The results indicate significant impact of tunnel closures on the network traffic conditions due to the redistribution of vehicles on alternative paths. Effects are also found on the performance of public transport. Analysis of the demand reveals redistribution of traffic during the tunnel closures, consistent with the observed impacts on network performance. Evidence for redistribution of travelers to public transport is observed as a potential effect of the closures. Better understanding of multimodal impacts of a disruption can assist authorities in their decision-making process to apply adequate traffic management policies.
|
|
| 41. |
|
|
| 42. |
- Zhang, Wei, et al.
(författare)
-
Coordination for heavy-duty vehicle platoon formation considering travel time variance
- 2015
-
Konferensbidrag (refereegranskat)abstract
- Forming a platoon has the potential to reduce the overall drag, providing economic and ecological benefitssuch as reduced energy consumption, increased safety and a more efficient utilization of roadinfrastructure. Previous research on platoon coordination has mainly focused on local control of platoonformation at highway on‐ramps and off‐ramps, or large‐network coordination strategy based on real‐timevehicle‐to‐vehicle communication. The platoon scheduling problem, however, has been barely explored.This study investigates the optimization of platoon scheduling problem, which is defined as theminimization of the total cost of all vehicles, including travel cost, early or late penalty and fuelconsumption. The travel cost is modelled as driver wage of certain travel time, which is comprised ofrecurrent travel time and non‐recurrent delay. Non‐recurrent delay is a random variable independent ofdeparture time. If the actual arrival time is earlier than the preferred arrival time, an early penalty isincurred. Otherwise a late penalty, which has a greater weight coefficient than early penalty, is incurred.Fuel consumption is a nonlinear function of travel time and platooning state. All vehicles in the platoonexcept the leader will experience an air‐drag reduction. The fuel cost caused by air drag only composes partof the total fuel consumption, from the perspective of energy conservation. For this nonlinear stochasticprogramming problem, a solution is proposed for the platoon‐or‐not‐platoon dilemma. Moreover, theoptimal departure time of the platoon is given when it is more beneficial to form a platoon than drivingindividually. Several numerical examples are presented to study the influences of different unit costparameters, together with various assumptions of the distribution of non‐recurrent delay, on the optimaldeparture time. The model enables the operator to predict the expected cost of platooning and scheduleadjustment and make a reasonable decision.
|
|
| 43. |
|
|
| 44. |
- Zhang, Wei, et al.
(författare)
-
Efficiency of semi-autonomous and fully autonomous bus services in trunk-and-branches networks
- 2019
-
Ingår i: Journal of Advanced Transportation. - : Hindawi Publishing Corporation. - 0197-6729 .- 2042-3195.
-
Tidskriftsartikel (refereegranskat)abstract
- Automation technology is expected to change the public transport sector radically in the future. One rising issue is whether to embrace the intermediate stage of semi-autonomous buses or to wait until fully autonomous buses are available. This paper proposes a cost model of bus operations considering automation technology. The generalized cost, which is the sum of waiting, riding, operating, and capital cost, is modeled for conventional, semi-autonomous, and fully autonomous bus services on a generic trunk-and-branches network. Semi-autonomous buses achieve reduced unit operating cost through automated platooning on the corridor. The relative efficiency of the different services is studied under a range of scenarios for commercial speed, network structure, and demand distribution. Analytical and numerical results show that fully autonomous buses exhibit great potential through reduced operating and waiting costs even if the additional capital cost is high. The advantages of semi-autonomous buses are weaker and most prominent in networks with low demand along a long corridor such as interurban networks. For both automation levels a commercial speed comparable to conventional vehicles is crucial. The established criteria provide input to planners and operators for understanding the potential of automated bus services.
|
|
| 45. |
- Zhang, Wei
(författare)
-
Planning and evaluation of autonomous vehicles in freight and public transport services
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of automation technology in transport systems brings both opportunities and challenges. The direct benefits of automation technology are obvious, for instance, reduced marginal driving cost, improved energy efficiency and increased safety. However, factors such as additional vehicle acquisition cost might hinder the implementation of autonomous vehicles, especially in the early stages when mass production is not realized yet. Besides, some benefits require large-scale applications or cooperation among multiple vehicles, while the low market penetration rate of autonomous vehicles may make system-specific benefits insignificant. Without proper planning and operation schemes, the advantages of automation technology can be cancelled out by its disadvantages. Given that the advantages of individual autonomous vehicles have been extensively explored, it is necessary to estimate the efficiency of transport systems involving autonomous vehicles. This thesis intends to solve the operation problem of autonomous vehicles in freight and public transport systems, focusing on system cost analysis.In freight transport, semi-autonomous truck platooning is a promising way to reduce fuel consumption. By instructing vehicles to form groups and drive together closely, the trailing vehicles experience reduced air resistance from the leading vehicle, and thus less fuel consumption. However, in practice, freight transport companies should also take time windows and transport reliability into consideration. The study answers the questions whether platoons should be formed and how significant can the savings be, considering driving cost, predefined time windows, travel time uncertainty and fuel cost. System optimization techniques, including stochastic optimization and mixed-integer linear programming, are adopted to minimize the total cost.In public transport, autonomous buses are assumed to save on-board crew cost, partially or fully. Similar with truck platoons, semi-autonomous buses can also form bus platoons for the purpose of eliminating the drivers from trailing buses. By contrast, fully autonomous buses are completely driverless and operates individually like conventional buses. To investigate the efficiency of autonomous buses, we compare the total cost of autonomous buses with conventional buses, where both passengers’ cost and service provider’s cost are modelled. In a general trunk-and-branches network connecting city center and suburbs, both fully autonomous bus and semi-autonomous bus systems are assessed. On a simple highly demanded corridor where demand varies during peak and off-peak hours, semi-autonomous bus platoons can be used as trains by extending its capacity in peak hours. Application of semi-autonomous vehicles are considered in traditional bus transit and BRT, by comparing with its conventional opponents.
|
|
