| 1. |
- Allström, Andreas, 1978-, et al.
(författare)
-
A hybrid approach for short-term traffic state and travel time prediction on highways
- 2016
-
Ingår i: TRB 95th annual meeting compendium of papers.
-
Konferensbidrag (refereegranskat)abstract
- Traffic management and traffic information are essential in urban areas, and require a good knowledge about both the current and the future traffic state. Both parametric and non-parametric traffic state prediction techniques have previously been developed, with different advantages and shortcomings. While non-parametric prediction has shown good results for predicting the traffic state during recurrent traffic conditions, parametric traffic state prediction can be used during non-recurring traffic conditions such as incidents and events. Hybrid approaches, combining the two prediction paradigms have previously been proposed by using non-parametric methods for predicting boundary conditions used in a parametric method. In this paper we instead combine parametric and non-parametric traffic state prediction techniques through assimilation in an Ensemble Kalman filter. As non-parametric prediction method a neural network method is adopted, and the parametric prediction is carried out using a cell transmission model with velocity as state. The results show that our hybrid approach can improve travel time prediction of journeys planned to commence 15 to 30 minutes into the future, using a prediction horizon of up to 50 minutes ahead in time to allow the journey to be completed.
|
|
| 2. |
- Allström, Andreas, et al.
(författare)
-
Calibration Framework based on Bluetooth Sensors for Traffic State Estimation Using a Velocity based Cell Transmission Model
- 2014
-
Ingår i: Transportation Research Procedia. - : Elsevier. - 2352-1465. ; 3, s. 972-981
-
Tidskriftsartikel (refereegranskat)abstract
- The velocity based cell transmission model (CTM-v) is a discrete time dynamical model that mimics the evolution of the traffic velocity field on highways. In this paper the CTM-v model is used together with an ensemble Kalman filter (EnKF) for the purpose of velocity sensor data assimilation. We present a calibration framework for the CTM-v and EnKF. The framework consists of two separate phases. The first phase is the calibration of the parameters of the fundamental diagram and the second phase is the calibration of demand and filter parameters. Results from the calibrated model are presented for a highway stretch north of Stockholm, Sweden.
|
|
| 3. |
- Allström, Andreas, 1978-, et al.
(författare)
-
Evaluation of travel time estimation based on LWR-v and CTM-v : A case study in Stockholm
- 2012
-
Ingår i: 15th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2012. - Piscataway, N.J, USA : IEEE. - 9781467330640 - 9781467330626 ; , s. 1644-1649
-
Konferensbidrag (refereegranskat)abstract
- Real-time estimations of current and future traffic states are an essential part of traffic management and traffic information systems. Within the Mobile Millennium project considerable effort has been invested in the research and development of a real-time estimation system that can fuse several sources of data collected in California. During the past year this system has been adapted to also handle traffic data collected in Stockholm. This paper provides an overview of the model used for highways and presents results from an initial evaluation of the system. As part of the evaluation process, GPS data collected in an earlier field-test and estimations generated by the existing system used by the TMC in Stockholm, are compared with the estimations generated by the Mobile Millennium system. Given that the Mobile Millennium Stockholm system has not undergone any calibration, the results from the evaluation are considered promising. The estimated travel times correspond well to those measured in the field test. Furthermore, the estimations generated by the Mobile Millennium system can be regarded as superior to those of existing traffic management system in Stockholm. The highway model was found to perform well even with a reduction in the number of sensors providing data. The findings of this study indicate the robustness of the Mobile Millennium system and demonstrate how the system can be migrated to other geographical areas with similar sources of available data.
|
|
| 4. |
- Allström, Andreas, 1978-, et al.
(författare)
-
Hybrid Approach for Short-Term Traffic State and Travel Time Prediction on Highways
- 2016
-
Ingår i: Transportation Research Record. - Washington, DC, USA : The National Academies of Sciences, Engineering, and Medicine. - 0361-1981 .- 2169-4052. ; 2554, s. 60-68
-
Tidskriftsartikel (refereegranskat)abstract
- Traffic management and traffic information are essential in urban areas and require reliable knowledge about the current and future traffic state. Parametric and nonparametric traffic state prediction techniques have previously been developed with different advantages and shortcomings. While nonparametric prediction has shown good results for predicting the traffic state during recurrent traffic conditions, parametric traffic state prediction can be used during nonrecurring traffic conditions, such as incidents and events. Hybrid approaches have previously been proposed; these approaches combine the two prediction paradigms by using nonparametric methods for predicting boundary conditions used in a parametric method. In this paper, parametric and nonparametric traffic state prediction techniques are instead combined through assimilation in an ensemble Kalman filter. For nonparametric prediction, a neural network method is adopted; the parametric prediction is carried out with a cell transmission model with velocity as state. The results show that the hybrid approach can improve travel time prediction of journeys planned to commence 15 to 30 min into the future, with a prediction horizon of up to 50 min ahead in time to allow the journey to be completed
|
|
| 5. |
- Allström, Andreas, 1978-, et al.
(författare)
-
Mobile Millennium Stockholm
- 2011
-
Ingår i: 2nd International Conference on Models and Technologies for Intelligent Transportation Systems.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- Allström, Andreas, et al.
(författare)
-
Traffic management for smart cities
- 2016
-
Ingår i: Designing, developing, and facilitating smart cities. - Switzerland : Springer. - 9783319449227 - 9783319449241 ; , s. 211-240
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Smart cities, participatory sensing as well as location data available in communication systems and social networks generates a vast amount of heterogeneous mobility data that can be used for traffic management. This chapter gives an overview of the different data sources and their characteristics and describes a framework for utilizing the various sources efficiently in the context of traffic management. Furthermore, different types of traffic models and algorithms are related to both the different data sources as well as some key functionalities of active traffic management, for example short-term prediction and control.
|
|
| 7. |
- Angelakis, Vangelis, et al.
(författare)
-
Mobility modeling for transport efficiency : Analysis of travel characteristics based on mobile phone data
- 2013
-
Ingår i: Netmob 2013.
-
Konferensbidrag (refereegranskat)abstract
- Signaling data from the cellular networks can provide a means of analyzing the efficiency of a deployed transportation system and assisting in the formulation of transport models to predict its future use. An approach based on this type of data can be especially appealing for transportation systems that need massive expansions, since it has the added benefit that no specialized equipment or installations are required, hence it can be very cost efficient.Within this context in this paper we describe how such obtained data can be processed and used in order to act as enablers for traditional transportation analysis models. We outline a layered, modular architectural framework that encompasses the entire process and present results from initial analysis of mobile phone call data in the context of mobility, transport and transport infrastructure. We finally introduce the Mobility Analytics Platform, developed by Ericsson Research, tailored for mobility analysis, and discuss techniques for analyzing transport supply and demand, and give indication on how cell phone use data can be used directly to analyze the status and use of the current transport infrastructure.
|
|
| 8. |
- Angelakis, Vangelis, et al.
(författare)
-
Security and Resilience in Cognitive Radio Networks
- 2011
-
Ingår i: European Research Consortium for Informatics and Mathematics Magazine. - 0926-4981. ; :85, s. 48-49
-
Tidskriftsartikel (refereegranskat)abstract
- After more than a decade of research, system securityand resilience is now the major technological barrier forthe Cognitive Radio (CR) to be adopted by the telecommunication industry. New ideas are required tomake CR networks secure and robust against attacks taking advantage the inherent characteristics of the CR functionality. This work explores key points that urgentlyneed to be addressed.
|
|
| 9. |
- Breyer, Nils, 1988-
(författare)
-
Analysis of Travel Patterns from Cellular Network Data
- 2019
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traffic planners are facing a big challenge with an increasing demand for mobility and a need to drastically reduce the environmental impacts of the transportation system at the same time. The transportation system therefore needs to become more efficient, which requires a good understanding about the actual travel patterns. Data from travel surveys and traffic counts is expensive to collect and gives only limited insights on travel patterns. Cellular network data collected in the mobile operators infrastructure is a promising data source which can provide new ways of obtaining information relevant for traffic analysis. It can provide large-scale observations of travel patterns independent of the travel mode used and can be updated easier than other data sources. In order to use cellular network data for traffic analysis it needs to be filtered and processed in a way that preserves privacy of individuals and takes the low resolution of the data in space and time into account. The research of finding appropriate algorithms is ongoing and while substantial progress has been achieved, there is a still a large potential for better algorithms and ways to evaluate them.The aim of this thesis is to analyse the potential and limitations of using cellular network data for traffic analysis. In the three papers included in the thesis, contributions are made to the trip extraction, travel demand and route inference steps part of a data-driven traffic analysis processing chain. To analyse the performance of the proposed algorithms, a number of datasets from different cellular network operators are used. The results obtained using different algorithms are compared to each other as well as to other available data sources.A main finding presented in this thesis is that large-scale cellular network data can be used in particular to infer travel demand. In a study of data for the municipality of Norrköping, the results from cellular network data resemble the travel demand model currently used by the municipality, while adding more details such as time profiles which are currently not available to traffic planners. However, it is found that all later traffic analysis results from cellular network data can differ to a large extend based on the choice of algorithm used for the first steps of data filtering and trip extraction. Particular difficulties occur with the detection of short trips (less than 2km) with a possible under-representation of these trips affecting the subsequent traffic analysis.
|
|
| 10. |
- Breyer, Nils, 1988-, et al.
(författare)
-
Cellpath Routing and Route Traffic Flow Estimation Based on Cellular Network Data
- 2018
-
Ingår i: The Journal of urban technology. - : Taylor & Francis. - 1063-0732 .- 1466-1853. ; :2, s. 85-104
-
Tidskriftsartikel (refereegranskat)abstract
- The signaling data in cellular networks provide means for analyzing the use of transportation systems. We propose methods that aim to reconstruct the used route through a transportation network from call detail records (CDRs) which are spatially and temporally sparse. The route estimation methods are compared based on the individual routes estimated. We also investigate the effect of different route estimation methods when employed in a complete network assignment for a larger city. Using an available CDR dataset for Dakar, Senegal, we show that the choice of the route estimation method can have a significant impact on resulting link flows.
|
|
| 11. |
- Breyer, Nils, 1988-, et al.
(författare)
-
Comparative Analysis of Travel Patterns from Cellular Network Data and an Urban Travel Demand Model
- 2020
-
Ingår i: Journal of Advanced Transportation. - : John Wiley & Sons. - 0197-6729 .- 2042-3195.
-
Tidskriftsartikel (refereegranskat)abstract
- Data on travel patterns and travel demand are an important input to today’s traffic models used for traffic planning. Traditionally, travel demand is modelled using census data, travel surveys, and traffic counts. Problems arise from the fact that the sample sizes are rather limited and that they are expensive to collect and update the data. Cellular network data are a promising large-scale data source to obtain a better understanding of human mobility. To infer travel demand, we propose a method that starts by extracting trips from cellular network data. To find out which types of trips can be extracted, we use a small-scale cellular network dataset collected from 20 mobile phones together with GPS tracks collected on the same device. Using a large-scale dataset of cellular network data from a Swedish operator for the municipality of Norrköping, we compare the travel demand inferred from cellular network data to the municipality’s existing urban travel demand model as well as public transit tap-ins. The results for the small-scale dataset show that, with the proposed trip extraction methods, the recall (trip detection rate) is about 50% for short trips of 1-2 km, while it is 75–80% for trips of more than 5 km. Similarly, the recall also differs by a travel mode with more than 80% for public transit, 74% for car, but only 53% for bicycle and walking. After aggregating trips into an origin-destination matrix, the correlation is weak () using the original zoning used in the travel demand model with 189 zones, while it is significant with when aggregating to 24 zones. We find that the choice of the trip extraction method is crucial for the travel demand estimation as we find that the choice of the trip extraction method is crucial for the travel demandestimation as we find systematic differences in the resulting travel demand matrices using two different methods.
|
|
| 12. |
- Breyer, Nils, 1988-
(författare)
-
Methods for Travel Pattern Analysis Using Large-Scale Passive Data
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Comprehensive knowledge of travel patterns is crucial to enable planning for a more efficient traffic system that accommodates human mobility demand. Currently, this knowledge is mainly based on traffic models based on relatively small samples of observations collected from travel surveys and traffic counts. The data is expensive to collect and provides only partial observations of travel patterns. With the rise of new technology, new largescale passive data sources can be used to analyse travel patterns. This thesis aims to expand the knowledge about how to use cellular network data collected by cellular network operators and smart-card data from public transit systems to analyse travel patterns. The focus is particularly on the data processing methods needed to extract travel patterns. The thesis’s contributions include new methods for extracting trips, estimating travel demand, route inference and travel mode choice from cellular network data and a method to extract travel behaviour changes from smart-card data. Different approaches are proposed to evaluate the methods: the validation using experimental data, validation using other available data sources, and comparison of results obtained using different methods. The findings include that methods for extracting travel patterns from largescale passive data need to account for the data’s characteristics. Paper II illustrates that route inference from Call Detail Records by strictly following the used cell towers’ locations is problematic due to the noise and low resolution of the data. Both rule-based and machine learning methods can be used to extract travel patterns. Paper I shows that a rule-based stop detection algorithm can be used to extract longer trips from cellular network data reliably. On the other hand, Paper III shows that for travel mode classification of trips extracted from cellular network data, supervised classification can outperform rule-based methods. Unsupervised machine learning can be used to find patterns without prior specification. Paper V shows how clustering of smart-card data could be used to group public transit users by travel behaviour to understand the effects of a disruption. Supervised machine learning requires training data. When no or little training data is available, using semi-supervised learning is a promising approach as demonstrated in Paper IV. In the studies of this thesis, real-world, large-scale passive datasets have been used to demonstrate how the extraction of travel patterns works under realistic circumstances. This has exposed limitations due to the data source’s characteristics and limitations due to possible sample bias. At the same time, the studies of this thesis show the potential of using large-scale passive data. Changes in travel patterns can be identified quickly as new data can be collected continuously. Due to the large sample size, the data allows understanding travel patterns based on observations instead of relying on traffic models’ underlying assumptions.
|
|
| 13. |
- Breyer, Nils, 1988-, et al.
(författare)
-
Semi-supervised Mode Classification of Inter-city Trips from Cellular Network Data
- 2022
-
Ingår i: Journal of Big Data Analytics in Transportation. - : Springer. - 2523-3564 .- 2523-3556. ; :1, s. 23-39
-
Tidskriftsartikel (refereegranskat)abstract
- Good knowledge of travel patterns is essential in transportation planning. Cellular network data as a large-scale passive data source provides billions of daily location updates allowing us to observe human mobility with all travel modes. However, many transport planning applications require an understanding of travel patterns separated by travel mode, requiring the classification of trips by travel mode. Most previous studies have used rule-based or geometric classification, which often fails when the routes for different modes are similar or supervised classification, requiring labelled training trips. Sufficient amounts of labelled training trips are unfortunately often unavailable in practice. We propose semi-supervised classification as a novel approach of classifying large sets of trips extracted from cellular network data in inter-city origin–destination pairs as either using road or rail. Our methods require no labelled trips which is an important advantage as labeled data is often not available in practice. We propose three methods which first label a small share of trips using geometric classification. We then use structures in a large set of unlabelled trips using a supervised classification method (geometric-labelling), iterative semi-supervised training (self-labelling) and by transferring information between origin–destination pairs (continuity-labelling). We apply the semi-supervised classification methods on a dataset of 9545 unlabelled trips in two inter-city origin–destination pairs. We find that the methods can identify structures in the cells used during trips in the unlabelled data corresponding to the available route alternatives. We validate the classification methods using a dataset of 255 manually labelled trips in the two origin–destination pairs. While geometric classification misclassifies 4.2% and 5.6% of the trips in the two origin–destination pairs, all trips can be classified correctly using semi-supervised classification.
|
|
| 14. |
- Breyer, Nils, 1988-, et al.
(författare)
-
Travel mode classification of intercity trips using cellular network data
- 2021
-
Ingår i: Transportation Research Procedia. - Paphos, Cyprus : Elsevier. ; , s. 211-218
-
Konferensbidrag (refereegranskat)abstract
- Many applications in transport planning require an understanding of travel patterns separated by travel mode. To use cellular network data as observations of human mobility in these applications, classification by travel mode is needed. Existing classification methods for GPS-trajectories are often inefficient for cellular network data, which has lower resolution in space and time than GPS data.In this study, we compare three geometry-based mode classification methods and three supervised methods to classify trips extracted from cellular network data in intercity origin-destination pairs as either road or train. To understand the difficulty of the problem, we use a labeled dataset of 255 trips in two OD-pairs to train the supervised classification methods and to evaluate the classification performance. For an OD-pair where the road and train routes are not separated by more than four kilometers, the geometry-based methods classify 4.5% - 7.1% of the trips wrong, while two of the supervised methods can classify all trips correctly. Using a large-scale dataset of 29037 trips, we find that separation between classes is less evident than in the labeled dataset and show that the choice of classification methods impacts the aggregated modal split estimate.
|
|
| 15. |
- Breyer, Nils, 1988-, et al.
(författare)
-
Trip extraction for traffic analysis using cellular network data
- 2017
-
Ingår i: 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems (MT-ITS). - Naples : IEEE Press. - 9781509064847 ; , s. 321-326
-
Konferensbidrag (refereegranskat)abstract
- To get a better understanding of people’s mobility, cellular network signalling data including location information, is a promising large-scale data source. In order to estimate travel demand and infrastructure usage from the data, it is necessary to identify the trips users make. We present two trip extraction methods and compare their performance using a small dataset collected in Sweden. The trips extracted are compared with GPS tracks collected on the same mobiles. Despite the much lower location sampling rate in the cellular network signalling data, we are able to detect most of the trips found from GPS data. This is promising, given the relative simplicity of the algorithms. However, further investigation is necessary using a larger dataset and more types of algorithms. By applying the same methods to a second dataset for Senegal with much lower sampling rate than the Sweden dataset, we show that the choice of the trip extraction method tends to be even more important when the sampling rate is low.
|
|
| 16. |
- Brusselaers, Nicolas, PhD, 1993-, et al.
(författare)
-
Decision support for improved construction traffic management and planning
- 2024
-
Ingår i: Sustainable cities and society. - : Elsevier. - 2210-6707. ; 104
-
Tidskriftsartikel (refereegranskat)abstract
- Densifying cities continuously call for new construction, renovation and demolition projects, each generating vast amounts of heavy goods vehicle (HGV) transports. However, how construction transportation affects the urban traffic network remains largely unexplored. This study addresses spatiotemporal network impacts from construction transport, by leveraging traditional traffic and transport simulation. To this end, a framework is presented including (i) a simulation model to compute traffic effects caused by varying off-site construction site transport demands, and (ii) conceptual applications of the simulation model showing construction logistic planning strategies to mitigate congestion disturbances. Simulations are conducted in MATSim using detailed secondary datasets describing site-specific transport arrivals from a case of six projects in Norrköping, Sweden. Subsequently, increasing transport demands were assessed on various time-window arrival scenarios against the baseline schedule, which can be used as decision support in urban planning. Results highlight how rigorous construction transport planning avoiding peak-traffic hours can significantly alleviate traffic congestion. This study also emphasizes the need to combine all simultaneous construction projects’ demands when evaluating disturbances on city-level, alongside the impact on individual links and microenvironments. This study adds knowledge by visualizing the traffic impact during urban transformation.
|
|
| 17. |
- Burghout, Wilco, et al.
(författare)
-
Multimodal Traffic Management : Project Report
- 2024
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nya system för att kombinera transportsätt, till exempel Mobility as a Service (MaaS), ger nya möjligheter för trafikanter att växla mellan olika färdmedel. Samtidigt ger stora mängder data från såväl kollektivtrafiknätet som vägtrafiknätet samt multimodala data från mobilnäten i kombination med nya metoder för att uppskatta resmönster uppdelat på färdmedel möjligheter till en helt ny förståelse av multimodala resmönster i en stad. Att förstå hur multimodala resmönster utvecklas över tid ger nya möjligheter att utveckla effektiva verktyg för multimodal trafikledning.Det övergripande målet med projektet är att möjliggöra förbättrad tillgänglighet i transportsystemen genom effektivare trafikledning. Mer specifikt syftar projektet till att utveckla nya metoder för att uppskatta multimodal efterfrågan samt färdmedelsval och ruttval för multimodal trafikledning. Vidare har potentiella effekter av multimodal trafikledning analyserats.Projektet omfattar en litteraturstudie för analys av möjligheter och utmaningar med multimodal trafikledning. En explorativ analys baserad på oövervakat lärande har utförts för att identifiera typiska nätverksövergripande mobilitetsmönster. Val av rutt och färdmedel har predikterats med hjälp av statistiska modeller. Ett multimodalt dataset för fem veckor i Stockholm med storskalig mobilitetsdata för vägnätet och biljettdata för kollektivtrafiknätet har sammanställs för den explorativa analysen samt utvärderingen av rutt- och transportsättsmodellerna i samband med trafikledning.Baserat på litteraturstudien kan vi dra slutsatsen att koordinerad ledning av väg och kollektivtrafik har potential att minska trängseln och säkerställa effektiv förflyttning av resenärer i ett storstadsområde. Det finns flera motiv för multimodal trafikledning, där de viktigaste är potentiellt ökad efterfrågan för kollektivtrafik, förbättrad robusthet för transportsystemet och bättre prioritering av trafikledningsåtgärder. De största utmaningarna är samarbete mellan intressenter, informationsdelning och datafusion.Resultaten av den explorativa analysen baserad på oövervakad inlärning indikerar att klustring för att ta fram typdagar kan vara användbart vid scenarioutvärdering, men också fungera som input till korttidsprediktion, vilket ger en enkel och robust predikteringsmetod för länkflöden med ett MAPE-prediktionsfel på 10-15 %.Ruttvalsanalysen visar att en modell baserad på en ruttuppsättning med genererade rutter är mer responsiv för restidsförändringar än en modell baserad på endast observerade rutter, vilket är användbart för att förutspå effekten av olika trafikledningsåtgärder. En ruttvalsmodell med enbart restid är en vanlig förenkling att använda för att prediktera ruttval, men resultatet i denna studie visar att inkludering av fler attribut avsevärt förbättrar modellernas prestanda.Analysen av nätverksövergripande multimodala data för 5 veckor i Stockholm indikerar att det är möjligt att uppskatta hur transportsättsandelen mellan kollektivtrafik och andra transportslag varierar i tid och rum. En bättre förståelse för spatiotemporal variation av färdmedelsvalet är en viktig input till förbättrat beslutsstöd i multimodal trafikledning.
|
|
| 18. |
- 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.
|
|
| 19. |
|
|
| 20. |
- 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.
|
|
| 21. |
- Cebecauer, Matej, et al.
(författare)
-
Revealing representative day-types in transport networks using traffic data clustering
- 2023
-
Ingår i: Journal of Intelligent Transportation Systems / Taylor & Francis. - : Informa UK Limited. - 1547-2450 .- 1547-2442. ; , s. 1-24
-
Tidskriftsartikel (refereegranskat)abstract
- Recognition of spatio-temporal traffic patterns at the network-wide level plays an important role in data-driven intelligent transport systems (ITS) and is a basis for applications such as short-term prediction and scenario-based traffic management. Common practice in the transport literature is to rely on well-known general unsupervised machine-learning methods (e.g., k-means, hierarchical, spectral, DBSCAN) to select the most representative structure and number of day-types based solely on internal evaluation indices. These are easy to calculate but are limited since they only use information in the clustered dataset itself. In addition, the quality of clustering should ideally be demonstrated by external validation criteria, by expert assessment or the performance in its intended application. The main contribution of this paper is to test and compare the common practice of internal validation with external validation criteria represented by the application to short-term prediction, which also serves as a proxy for more general traffic management applications. When compared to external evaluation using short-term prediction, internal evaluation methods have a tendency to underestimate the number of representative day-types needed for the application. Additionally, the paper investigates the impact of using dimensionality reduction. By using just 0.1% of the original dataset dimensions, very similar clustering and prediction performance can be achieved, with up to 20 times lower computational costs, depending on the clustering method. K-means and agglomerative clustering may be the most scalable methods, using up to 60 times fewer computational resources for very similar prediction performance to the p-median clustering.
|
|
| 22. |
- Cebecauer, Matej, et al.
(författare)
-
Spatio-Temporal Public Transport Mode Share Estimation and Analysis Using Mobile Network and Smart Card Data
- 2023
-
Ingår i: 2023 IEEE 26th International Conference on Intelligent Transportation Systems (ITSC). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 2543-2548
-
Konferensbidrag (refereegranskat)abstract
- Public transport plays a vital role in society and the urban environment. However, knowledge of its spatial and temporal shares is often limited to traditional travel surveys. Recently, there has been substantial progress in mobility data collection, including data from traffic, public transport, and mobile phones. Especially mobile network data is a large-scale and affordable source of high-level mobility records. Similarly, public transport smart cards or ticket validation data are being collected and made available in major cities. The contribution of this study is to unveil the potential of estimating public transport shares, by merging mobile and smart card data. Stockholm, Sweden, is used as a case study. We analyze and discuss spatio-temporal patterns of estimated public transport shares for Stockholm, using descriptive and cluster analysis. The typical representative day-types are revealed and analyzed. Finally, a regression analysis considering the weather and socioeconomic context is conducted. It provides a highly explanatory and predictive understanding of which factors impact the share of public transport in Stockholm. To conclude, combined mobile and smart card data offers a cost-efficient, large-scale, low spatio-temporal aggregation (capturing daily and hourly variations) alternative to traditional travel surveys for analyzing PT shares.
|
|
| 23. |
- Cebecauer, Matej, et al.
(författare)
-
Using flows or speeds in traffic pattern clustering and prediction : does the data type matter?
- 2022
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Data and knowledge of travel patterns play a key role in finding more cost-effective solutions and better utilization of existing resources to increase sustainability and decrease CO2 emissions, pollution, and noise. Understanding travel patterns and prediction of future traffic states is a central ingredient in Intelligent transport systems (ITS). Pre-clustering the data before applying the prediction models is a recommended practice. We consider in this work revealing day-to-day traffic regularities and grouping days into representative day-types based on their traffic similarities before training prediction models. Specifically for this presentation, we will present our recent work on day-type clusterings that concern the similarities and interchangeability of day-types recognized by flow and speed traffic measurements. We consider the speed and flow traffic measurements from the motorway control system in the highway system around Stockholm, Sweden. Different clustering methods are used and their performance is evaluated on short-term prediction models. The results reveal that day-types are similar across data types and clustering methods, and their similarity does not depend much on the number of clusters. As the baseline scenario, calendar-based day-types are used. The similarity is higher between flow and speed recognized day-types compare to calendar-based day-types. Considering short-term prediction performance, the data-driven day-types outperform calendar-based methods. However, for more sophisticated prediction models the difference becomes insignificant. The interchangeability of speeds and flows in traffic prediction is studied in a scenario where new days are classified into day-types based on speed observations. This could be particularly interesting for traffic management centers as speed observations may be collected in more affordable, sustainable, and scalable ways. However, results reveal that flow prediction is sensitive to whether the new day is classified to one of the clusters using speed instead of flow observations, and prediction performance is reduced by about 28%. This sensitivity can be overcome by using a more sophisticated prediction model. When classifying based on flow observations a more sophisticated model results in slight improvements in speed prediction.
|
|
| 24. |
- Danielsson, Anna, 1995-, et al.
(författare)
-
Analysis of Route Sets and Attributes in Route Choice Estimation for Urban Traffic Management Using GPS Data
- 2024
-
Ingår i: Proceedings of the 103rd Transportation Research Board Annual Meeting.
-
Konferensbidrag (refereegranskat)abstract
- Efficient traffic management requires an understanding of mobility patterns in the road network, where one important component is route choice. This study aims to analyze how route choice models can be adapted to efficient urban traffic management and intelligent transport systems (ITS), by constructing route sets and attributes from GPS and network data. With a route choice model that is responsive to traveltime changes in the network, travel behavior during incidents can be predicted to evaluate traffic management policies, such as traveler information and traffic control. The dataset consists of about 400,000 vehicle trips and is divided into a training dataset and a test dataset. The two datasets are compared, and the experiments show that the routes used are similar. Discrete route choice models are estimated with one data-driven path identification approach (DDPI) and one where the data-driven path set is augmented with routes from a network-based shortest path generation with link penalty (NBPA). The result suggests that the traveltime has a larger impact on the route choice when the model is trained on the NBPA route set and that the route's simplicity, length, and traveltime are important attributes for the route choice, which are useful insights in a traffic management context.
|
|
| 25. |
- Danielsson, Anna, 1995-
(författare)
-
Towards efficient urban road transport using multimodal traffic management
- 2024
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As travel demand and urbanization increase, they cause road con-gestion. This results in lost productivity, reduced accessibility, and negative effects on the environment. Solutions to reduce congestion in the transport network include urban traffic management. It could for example be regulating signal control, variable speed limit, and ramp metering, or distributing traveler information about traveltimes and congestion through radio broadcasts, variable message signs, or navigation apps. A multimodal traffic management system utilizes several transportation modes within an integrated system to improve network performance and robustness. Large-scale mobility data from both the public transport network and private vehicles enable a better understanding of multimodal travel patterns. Traffic data can also be used to estimate reliable traffic models that can support evaluation and prioritization of traffic management measures. The aim of the thesis is to identify synergies and challenges of multimodal traffic management. The aim includes analyzing, devel-oping, and evaluating dynamic route choice models that can support multimodal traffic management decisions, using large-scale passive mobility data. First, recent trends are explored in the transition to more efficient road transport, emphasizing the role of monitoring and modeling traffic. Second, related literature is surveyed to identify the potential synergies and challenges of multimodal traffic management. Requirements of data and models in a decision support system that can help to prioritize between multimodal traffic management measures are also identified. Based on these requirements, route choice in the road network is analyzed using GPS trajectory data. This provides insights into how data-driven route choice models can be a component in multimodal traffic management. The thesis contributes to the understanding of how a decision support system for multimodal traffic management can be developed, how route choice modeling can be used in such a tool, and how multimodal traffic management is needed in the transition towards more efficient road transport.
|
|
| 26. |
|
|
| 27. |
- Forsman, Åsa, 1972-, et al.
(författare)
-
Utvärdering av hastighetsmätningar med blåtandssensorer : jämförelse med data från MCS (Motorway Control System)
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med det här projektet har varit att utvärdera hur väl hastighetsmätningar som beräknats med hjälp av data från blåtandssensorer stämmer överens med radarmätningar. Av speciellt intresse har varit att utvärdera om metoden skulle kunna användas vid före-efter studier av trafiksäkerhetsåtgärder som till exempel trafiksäkerhetskameror eller andra hastighetsdämpande åtgärder. Utvärderingen baseras på data från två mätplatser på E4:an strax norr om Stockholm.Resultaten från studien visar att:• Penetrationsgraden (andel blåtandspassager per passerat fordon) varierar mellan 12 och 16 procent beroende på plats och om det är vardag eller helg.• Blåtandsmätningarna ger stabila resultat med avseende på medelhastigheten på dygnsnivå. Jämförelser med MCS-data visar att resultaten från de två mätmetoderna följer varandra väl och differensen mellan metoderna är ungefär lika stor från dygn till dygn.• Hastighetsmätningar med blåtandssensorer bedöms vara tillräckligt tillförlitliga, på den studerade vägtypen, för att kunna användas i utvärderingar av olika trafiksäkerhetsåtgärder.
|
|
| 28. |
- Fredriksson, Anna, 1979-, et al.
(författare)
-
Construction related urban disturbances : Identification and linking with an IoT-model
- 2022
-
Ingår i: Automation in Construction. - : Elsevier. - 0926-5805 .- 1872-7891. ; 134
-
Tidskriftsartikel (refereegranskat)abstract
- While being a significant part of the urban development, construction projects disturb different stakeholders in various ways. There are three problems associated with construction disturbances: (i) most of these disturbances are not recognised by the people causing them, (ii) they are not monitored and (iii) if they are to be monitored, data is spread among stakeholders. This paper defines what a disturbance is, presents a list of disturbances, linking disturbances to stakeholders and, categorising them based on their distance from construction sites (responding to (i)). Next, a IoT domain model is developed, demonstrating how IoT in construction needs to be combined with the sensors of smart cities to capture the primitives of these disturbances (responding to (iii)). This is a first step towards enabling large-scale data-gathering of construction transport disturbances (responding to (ii)), which is a necessity to predict them and allow better construction transport planning to decrease disturbances.
|
|
| 29. |
- Fredriksson, Anna, 1979-, et al.
(författare)
-
Störningsfri stad : slutrapport i projektet Visualiserad byggtrafikplanering för en störningsfri stadsutveckling
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Störningsfri stad har kombinerat kunskaper inom Trafikplanering, Visualisering, Bygglogistik, Sensorer och Offentlig planering och styrning. Projektet har letts av Linköpings universitet, Institutionen för Teknik och Naturvetenskap och finansierats av Vinnova, IHS. Projektet har löpt mellan slutet av 2018 och 2021 ut. Projektdeltagare har varit VTI, RISE, Norrköpings kommun, Linköpings kommun, Stockholm stad, Uppsala kommun, Trafikverket Projekt Ostlänken, LE Lundbergs Fastigheter, Wiklunds Åkeri, Wellsec, SanktKors, Byggföretagen, Telenor och Logistikia.Projektet har utvecklat en verktygsprototyp som stöttar kollaborativ planering av byggtrafik och stadsplanering genom att visualisera pågående byggprojekts sammanlagda mängd transporter och var i staden (i form av en kartvy) det uppstår störningar i form av förseningar pga dessa. Verktyget bygger på en MATSim trafikmodell (i nuläget Norrköping) inkluderande både persontransporter (modellerat baserat på mobilnätsdata) och byggtrafik (modellerat baserat på data från bygglogistiklösningar). Med hjälp av verktyget kan olika scenarier för att minska störningarna av byggtransporter testas. För att stötta användandet av verktyget har en kollaborativ planeringsprocess som visar på hur de olika aktörerna involverade i planeringen av byggtransporter och stadsutveckling behöver interagera med varandra utvecklats. Projektet också deltagit i utvecklingen av en sensorbox (partiklar, luftfuktighet, temperatur och ljud) samt slangmätningsmetodik för att öka kunskapen om byggtransporter. Baserat på de resultat som projektet har behovsägarna har påbörjat arbeten med att bättre hantera de störningar som uppstår pga byggprojekt i staden.
|
|
| 30. |
- Grumert, Ellen, 1983-, et al.
(författare)
-
Effects of incidents on motorways : a proposed methodology for estimating and predicting demand, duration and capacity for incident management
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Effective traffic incident management is important to minimize negative impacts of congestion caused by incidents. Predictions of the traffic state at the incident site and its surrounding road network, together with an estimate of incident duration, can be used to get increased knowledge about current and future incident characteristics. The aim is to propose methods for estimating capacity, duration and demand profiles in case of an incident, and to explore how the level of detail and the possibility to identify explanatory variables for incidents with similar characteristics given currently available data sources affects the proposed methods. The knowledge obtained within the project is intended to be used for incident management. The report presents a methodology for predicting capacity, traffic demand, and incident duration, when none of the parameters are known. The proposed methods can be used as input to traffic models, when the purpose is to perform scenario-based analysis and real-time predictions to be used in the decision-making processes for traffic management/control, but also for predicting travel times which can be communicated to road users.A motorway use-case study area south of Stockholm is used to propose methods for predicting incident duration, capacity and demand profiles based on the availability of data. The methodology is evaluated by using the predicted variables as input in a scenario-based analysis with two queue models.
|
|
| 31. |
- Grumert, Ellen, 1983-, et al.
(författare)
-
Förslag på metodik för systematisk utvärdering av ITS i motorvägsmiljö : en sensorbaserad ansats
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten är en av två rapporter som beskriver resultatet från projektet Utvärdering av förbättrad motorvägsstyrning – en fallstudie. Projektet har som syfte att ta fram en metodik för att utvärdera före- och efterstudier för ITS-åtgärder (Intelligenta Transport Systems-åtgärder) i motorvägsmiljö och applicera metodiken på en teststräcka på E4 vid Södertälje för att utvärdera tillämpbarheten av metoden samt effekter på framkomlighet, säkerhet och miljö. När man vill studera förändringar på grund av ITS-åtgärder på vägsträckor med tätt belägna sensorer finns goda möjligheter till före- och eftermätningar. I dagsläget saknas ofta sådana studier och det finns därmed begränsat med kunskap om hur sådana före-efterstudier bäst ska genomföras. Syftet med denna rapport är att ta fram ett förslag på utvärderingsmetodik med avseende på framkomlighet, trafiksäkerhet och miljö då tillgången på data från tätt belägna sensorer är god. I rapporten föreslås välgrundade metoder för att på ett rättvist sätt kunna jämföra före- och eftersituationen med varandra. En viktig aspekt är att identifiera dagar med likartade trafikförhållanden för att undvika att dagar med olika trafiksituationer och därmed i praktiken icke-jämförbara dagar ställs mot varandra vid utvärderingen av effekterna av ITS-åtgärden. Ytterligare en rapport presenterar resultaten från utvärderingen på teststräckan vid Södertälje.
|
|
| 32. |
|
|
| 33. |
- Grumert, Ellen, 1983-, et al.
(författare)
-
Utvärdering av styrning med variabla hastighetsgränser med fokus på framkomlighet : en fallstudie på E4 vid Södertälje
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten är en av två rapporter som beskriver resultatet från det Trafikverksfinansierade projektet Utvärdering av förbättrad motorvägsstyrning – en fallstudie. Projektet har som syfte att ta fram en metodik för att utvärdera före-efterstudier för ITS-åtgärder (Intelligenta Transport Systems-åtgärder) i motorvägsmiljö och applicera metodiken på en teststräcka på E4 vid Södertälje för att utvärdera tillämpbarheten av metoden samt effekter på framkomlighet, säkerhet och miljö. När man vill studera förändringar på grund av ITS-åtgärder på vägsträckor med tätt belägna sensorer finns goda möjligheter till före- och eftermätningar. I dagsläget saknas ofta sådana studier och det finns därmed begränsat med kunskap om hur sådana före-efterstudier bäst ska genomföras. Syftet med denna rapport är att applicera den metodik som har tagits fram i projektet och utvärdera effekter på framkomlighet, trafiksäkerhet och miljö för en fallstudie vid Södertälje. På sträckan har en ny styrstrategi för val av variabla hastighetsgränser implementerats. På teststräckan har det funnits tätt belägna detektorer, installerade på 150–300 meters avstånd, i många år. Eftersom det redan innan ny styrstrategi fanns på plats gavs goda möjligheter att mäta trafikförhållandena på teststräckan, ges ett unikt tillfälle att jämföra trafikförhållanden före och efter styrstrategin är implementerad. Resultaten från utvärderingen bidrar, utöver att utvärdera tillämpbarheten av metodiken, till kunskap om hur före[1]efterstudier bör designas och variabla hastighetsgränsers inverkan på trafiksituationen då målet är att förbättra trafikförhållanden vid framkomlighetsproblem.
|
|
| 34. |
- Grumert, Ellen, 1983-, et al.
(författare)
-
Variabla hastighetsgränser för Stockholms motorvägsnät : Effekter av alternativa algoritmer och möjligheter till styrning genom skattade trafiktillstånd
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Variabla hastighetsgränser är väl utbrett på Stockholms stadsnära motorvägar och en del av Stockholms Motorway Control System (MCS). Målet med dagens system är att minska risken för olyckor och följdolyckor vid låga hastigheter, trafikstockningar m.m. Detta görs genom att mäta medelhastigheten med hjälp av fasta detektorer och uppdatera hastigheten som visas på variabla meddelandeskyltar utifrån rådande trafiktillstånd. I och med att efterfrågan på resor i Stockholm under rusningstid överstiger den tillgängliga kapaciteten i vägnätet är behovet av ett effektivt trafiksystem stort. Variabla hastighetsgränser kan bidra till ökad framkomlighet, men då dagens system har som målsättning att öka säkerheten är effekter som leder till ökad framkomlighet begränsade. Dessutom finns det i dagens system ett stort beroende av fungerande detektorer som mäter trafiktillståndet så korrekt som möjligt för att valet av hastighet ska kunna bestämmas på ett effektivt sätt.Syftet med den här rapporten är att undersöka alternativa styralgoritmer för att bestämma variabla hastighetsgränser på Stockholms motorvägsnät. Målet är att öka framkomligheten jämfört med dagens system. Två olika sträckor med olika komplexitet, trafiksituation och problematik studeras. Valet av studerade styralgoritmer för de olika sträckorna väljs för att på bästa sätt motverka den problematiken som uppstår på de specifika sträckorna. Därmed kan val av algoritmer komma att skilja sig åt beroende på sträcka. I projektet utvärderas också om estimering av trafiktillståndet kan användas för att förbättra informationsflödet till algoritmerna då detektorer inte fungerar som de ska eller helt saknas, vilket i sin tur kan leda till förbättrad anpassning av de variabla hastighetsgränserna. Detta görs av för en av de studerade sträckorna. Styralgoritmerna utvärderas med mikroskopisk trafiksimulering och metoden utvecklad i projektet Mobile Millenium Stockholm (MMS), som bygger på en makroskopisk trafikflödesmodell och Kalman filtrering, används för estimering av trafiktillståndet.Resultatet visar att det finns styralgoritmer med potential att öka framkomligheten. Valet av styralgoritm är dock beroende av typ av trafiksituation, vägdesignens komplexitet och trafikförhållanden på vägen. Det betyder att olika styralgoritmer kan prestera olika bra beroende på vilken vägsträcka man studerar. Vidare är estimering av trafiktillståndet användbart vid förlorad information på grund av icke-fungerande detektorer eller som komplement till detektorer för att minska mängden stationär utrustning.
|
|
| 35. |
- Grumert, Ellen, 1983-, et al.
(författare)
-
Variabla hastighetsgränser för Stockholms motorvägsnät : effekter av alternativa algoritmer och möjligheter till styrning genom estimerade trafiktillstånd
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Variabla hastighetsgränser är väl utbrett på Stockholms stadsnära motorvägar och en del av Stockholms Motorway Control System (MCS). Målet med dagens system är att minska risken för olyckor och följdolyckor vid låga hastigheter, trafikstockningar m.m. Detta görs genom att mäta medelhastigheten med hjälp av fasta detektorer och uppdatera hastigheten som visas på variabla meddelandeskyltar utifrån rådande trafiktillstånd. I och med att efterfrågan på resor i Stockholm under rusningstid överstiger den tillgängliga kapaciteten i vägnätet är behovet av ett effektivt trafiksystem stort. Variabla hastighetsgränser kan bidra till ökad framkomlighet, men då dagens system har som målsättning att öka säkerheten är effekter som leder till ökad framkomlighet begränsade. Dessutom finns det i dagens system ett stort beroende av fungerande detektorer som mäter trafiktillståndet så korrekt som möjligt för att valet av hastighet ska kunna bestämmas på ett effektivt sätt.Syftet med den här rapporten är att undersöka alternativa styralgoritmer för att bestämma variabla hastighetsgränser på Stockholms motorvägsnät. Målet är att öka framkomligheten jämfört med dagens system. Två olika sträckor med olika komplexitet, trafiksituation och problematik studeras. Valet av studerade styralgoritmer för de olika sträckorna väljs för att på bästa sätt motverka den problematiken som uppstår på de specifika sträckorna. Därmed kan val av algoritmer komma att skilja sig åt beroende på sträcka. I projektet utvärderas också om estimering av trafiktillståndet kan användas för att förbättra informationsflödet till algoritmerna då detektorer inte fungerar som de ska eller helt saknas, vilket i sin tur kan leda till förbättrad anpassning av de variabla hastighetsgränserna. Detta görs av för en av de studerade sträckorna. Styralgoritmerna utvärderas med mikroskopisk trafiksimulering och metoden utvecklad i projektet Mobile Millenium Stockholm (MMS), som bygger på en makroskopisk trafikflödesmodell och Kalman filtrering, används för estimering av trafiktillståndet.
|
|
| 36. |
|
|
| 37. |
|
|
| 38. |
- Gundlegård, David, et al.
(författare)
-
Cellular Positioning Using Fingerprinting Based on Observed Time Differences
- 2013
-
Ingår i: <em>IEEE 4th International Conference on Smart Communications in Network Technologies (SaCoNet)</em>. - : IEEE conference proceedings. - 9781479906949 ; , s. 1-5
-
Konferensbidrag (refereegranskat)abstract
- Cellular positioning has been a very active research area for the last decade. Large improvement in accuracy has been made to support, for example, e-call and other location-based services. Traditionally, cellular positioning has been limited to cellular operators equipped with expensive synchronization hardware in order to achieve good accuracy. Lately, third parties have employed fingerprinting methods to enable positioning systems independent from the cellular operators. With improved available processing power, denser cellular networks, cheaper data collection and efficient pattern matching algorithms, the fingerprinting positioning methods have also gained popularity. In this paper, we analyzed the potential of using System Frame Number (SFN) - SFN observed time differences, which are traditionally used in Time Difference of Arrival (TDOA) positioning, for fingerprinting-based positioning. A field test was performed using measurements from TEMS (Telecommunication Management System) Investigation. By combining SFN-SFN observed time differences with Received Signal Code Power (RSCP) measurements, we demonstrated an improved accuracy of the fingerprinting method by 20% compared to only using RSCP measurements. The results are promising and show good potential in using SFN-SFN observed time differences for positioning based on fingerprinting.
|
|
| 39. |
- Gundlegård, David, et al.
(författare)
-
Clustering in Before-After Studies of ITS Measures
- 2024
-
Ingår i: 2023 IEEE 26th International Conference on Intelligent Transportation Systems (ITSC). - : IEEE. - 9798350399462 - 9798350399479 ; , s. 2671-2676
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Intelligent Transport System (ITS) measures are becoming more and more common on urban motorways. Different methods can be used to evaluate the effectiveness of the ITS measure, for example traffic simulation, cost-benefit analysis and before-after studies. A fundamental part of a before-after study is the choice of days for comparison of the before and after periods. Many previous before-after studies of ITS measures are based on simple methods for choosing comparable days, similar to the benchmark method used in this paper. For the chosen case study, a modified Variable Speed Limit (VSL) control strategy, we have used clustering to 1) quickly find similar days for evaluation, 2) identify type days with different characteristics and 3) identify deviating days that are non-representative for the before-after study. From the case study, it is clear that the choice of the days for evaluation are important and can generate different inference, and the clustering method provides promising results compared to the benchmark.
|
|
| 40. |
- Gundlegård, David
(författare)
-
Generating Road Traffic Information Based on Cellular Network Signaling
- 2013
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cellular networks of today generate a massive amount of signalling data. A large part of this signalling is generated to handle the mobility of subscribers, irrespective of the subscriber actively uses the terminal or not. Hence it contains location information that can be used to fundamentally change our understanding of human travel patterns.This thesis aims to analyse the potential and limitations of using this signalling data in the context of road traffic information, i.e. how we can estimate the road network traffic state based on standard signalling data already available in cellular networks. This is achieved by analytical examination and experiments with signalling data and measurements generated by standard cell phones.The thesis describes the location data that is available from signalling messages in GSM, GPRS and UMTS networks, both in idle mode and when engaged in a telephone call or a data session. The signalling data available in a ll three networks is useful to estimate traffic information, although the resolution in time and space will to a large extent depend on in which mode the terminal is operating.Spatial analysis of handover signalling data has been performed for terminals engaged in telephone calls. The analysis indicates that handover events from both GSM and UMTS networks can be used as efficient input to systems for travel time estimation, given that route classification and filtering of non -vehicle terminals can be solved.By analysing signalling data and received signal strength (RSS) measur ements from cell phones, it can be seen the route classification problem in the context of estimating travel times based on handover events is non -trivial even for highway environments. However, it is presented that the problem can be sa tisfactory solved for highway environments by using basic classification methods, like for example Bayesian classification.Furthermore the thesis points out that the new era of smartphones can be an enabler for road traffic information from cellular networks in the close future. By examining measurements collected by a smartphone client, it is illu strated how the radio map for cell phone positioning can be built by participatory sensing. It is also shown that the location accuracy of RSS-based cell phone positioning is accurate enough to p rovide both travel time and OD-matrix estimation.
|
|
| 41. |
- Gundlegård, David, 1978-, et al.
(författare)
-
Generating Road Traffic Information from Cellular Networks - New Possibilities in UMTS
- 2006
-
Ingår i: Proceedings 2006 6th International Conference onITS Telecommunications. - 0780395875 - 0780395875 ; , s. 1128-1133
-
Konferensbidrag (refereegranskat)abstract
- This paper summarizes different approaches to collecting road traffic information from second-generation cellular systems (GSM) and point out the possibilities that arise when third generation systems (UMTS) are used. Cell breathing is a potential problem, but smaller cells, soft handover and flexible measurements have the potential to increase the usage area and information quality when road traffic information is extracted from the UMTS network compared to using the GSM network
|
|
| 42. |
|
|
| 43. |
- Gundlegård, David, et al.
(författare)
-
Handover location accuracy for travel time estimation in GSM and UMTS
- 2009
-
Ingår i: IET Intelligent Transport Systems. - : Institution of Engineering and Technology (IET). - 1751-956X .- 1751-9578. ; 3:1, s. 87-94
-
Tidskriftsartikel (refereegranskat)abstract
- Field measurements from the GSM and UMTS networks are analysed in a road traffic information context. The measurements indicate a potentially large improvement using UMTS signalling data compared with GSM regarding handover location accuracy. These improvements can be used to generate real-time traffic information with higher quality and extend the geographic usage area for cellular-based travel time estimation systems. The results con. rm previous reports indicating that the technology has a large potential in GSM and also show that the potential might be even larger and more. exible using UMTS. Assuming that non-vehicle terminals can be. ltered out, that vehicles are tracked to the correct route and that handovers can be predicted correctly, a conclusion from the experiments is that the handover location accuracy in both GSM and UMTS will be sufficient to estimate useful travel times, also in urban environments. In a real system, these tasks are typically very challenging, especially in an urban environment. Further, it is reasonably established that the location error will be minor for the data obtained from UMTS.
|
|
| 44. |
- Gundlegård, David, et al.
(författare)
-
Integrated tracking and route classification for travel time estimation based on cellular network signalling data
- 2020
-
Ingår i: IET Intelligent Transport Systems. - : INST ENGINEERING TECHNOLOGY-IET. - 1751-956X .- 1751-9578. ; 14:9, s. 1087-1096
-
Tidskriftsartikel (refereegranskat)abstract
- This study evaluates the effectiveness of using detailed cellular network signalling data for travel time estimation and route classification. Here, the authors propose a processing pipeline for estimating travel times and route classification based on Cell ID and received signal strength (RSS) measurements from a cellular network. The pipeline combines cellular fingerprinting, particle filtering, integrity monitoring, and map matching based on a hidden Markov model (HMM). The method is evaluated using a dataset of 11,000 cellular RSS measurements with corresponding GPS locations for the city of Norrkoping, Sweden. The basic fingerprinting method has a CEP-67 location accuracy of 111 m and both particle filtering and integrity monitoring improved the results: 79 and 38 m for particle filtering and particle filtering with integrity monitoring, respectively. The route classification method resulted in a precision of 0.83 and a recall of 0.92, which are clear improvements compared to basic map matching of fingerprinting estimates. This new type of noise-adaptive travel time sampling in combination with an HMM-based route classification shows promising results and can potentially support large-scale estimates of both route choice and travel times using detailed cellular network signalling data in urban areas.
|
|
| 45. |
- Gundlegård, David, et al.
(författare)
-
Multimodal trafikledning
- 2024
-
Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 80-81
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Fyrstegsprincipen innebär att infrastruktur i första hand optimeras och byggs om än nyproduceras. I kombination med en ökande urbanisering gör det att trafiksystem ofta hanteras på gränsen av sin kapacitet. Små förändringar i utbud kan då få stor effekt på systemets prestanda och stor samhällsekonomisk påverkan. Därför är det viktigt med bra beslutsunderlag och analysverktyg för styrning av trafiken. Målet med trafikledning är delvis att utvärdera åtgärdsplaner i realtid, men dess huvudmål är att minska effekterna av incidenter för att få ett effektivt trafikflöde genom att guida trafikanter.Nya system för att kombinera transportsätt, exempelvis Mobility as a Service (MaaS), ger nya möjligheter för trafikanter att skifta mellan olika färdmedel. Samtidigt ger stora mängder data från kollektivtrafiknätet, vägtrafiknätet och mobilnätet i kombination med nya metoder för att skatta resmönster fördelat på färdmedel möjligheter till en ny förståelse för multimodala resmönster i en stad. Multimodal trafikledning syftar till en integrerad trafikledning för personresor med bil- och kollektivtrafik. Projektet Multimodal trafikledning syftar till att ta fram nya metoder för att skatta multimodal efterfrågan samt färdmedels- och ruttval vid incidenter för att möjliggöra bättre incidenthantering genom multimodal trafikledning.Projektet grundar sig i kvantitativ analys och modellering med hjälp av olika datakällor, exempelvis MCS-data från motorvägsnätet, detaljerade GPS-data från INRIX, mobilnätsdata från Telia, biljettdata från SL, GPS-data och tidtabelldata (GTFS) från bussar och incidentdata från Trafik Stockholm. Datadriven modellering av ruttval och färdmedelsval används för att förstå ruttval och färdmedelsval för bil- och kollektivtrafik, som i sin tur kan användas för att skatta och prediktera multimodal efterfrågan. Klustring används för att identifiera typdagar och som grund till att skatta och prediktera resmönster i det multimodala trafiknätet. Resultaten från projektet visar på potential i att kombinera olika datakällor för datadriven analys av multimodala resmönster som kan ge insikter för mulitmodal trafikledning. De framtagna metoderna har testats på ett nätverk i Stockholm både under normaltillstånd och med en incident och visade lovande resultat. I nuläget finns relativt få akademiska publikationer inom området multimodal trafikledning, men ett antal nystartade EU-projekt antyder att intresset för området växer.
|
|
| 46. |
|
|
| 47. |
- Gundlegård, David, et al.
(författare)
-
Probe-data för kontinuerlig skattning av OD-matriser och länkflöden (CODE PROBE)
- 2024
-
Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 86-87
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Nya storskaliga datakällor för mobilitet, som GPS-baserad probe-data och mobilnätdata, har på senare tid fått ökat intresse inom trafikplaneringsapplikationer. Dessa datakällor är baserade på kontinuerliga positionsobservationer av ett urval av enheter som möjliggör en helt ny förståelse av spatiotemporala mobilitetsmönster både inom och mellan städer. En storskalig mobilitetskälla av särskilt intresse för trafikplanering är GPS-baserad probe-data, som inkluderar högupplösta mobilitetsdata för några procent av fordonsparken. Datakällan har potential att automatisera trafikstatistik på nätverksnivå för tillämpning inom både trafikprognoser och nationell ekonomisk analys. I tidigare forskning har egenskaperna hos detaljerad GPS-data och möjliga applikationsområden analyserats för svenska förhållanden och länkflödesskattningar har identifierats som en prioriterad datatyp som är användbar för trafik- och infrastrukturplanering. Nyligen har forskning också använt probe-data som indata till skattning av efterfrågan i form av OD-matriser. Projektet ”Probe-data för kontinuerlig skattning av OD-matriser och länkflöden” (CODE PROBE) syftar till att jämföra och kombinera lokala probe-baserade länkflödesuppskattningar med konceptet datadriven nätverksutläggning och skattning av OD-matriser för kontinuerlig (24/7) och konsistent skattning av efterfrågan och länkflöde. Uppskalning av probe-data för direkt skattning av länk- och OD-flöden baseras på statistiska modeller, som exempelvis multipel linjär regression och trädbaserad regression, där modellen tränas med historiska data för att sedan kunna användas för skattning av länkflöden. Konceptet datadriven nätutläggning, som utvecklats vid LiU de senaste åren, har använts för att samtidigt skatta både OD- och länkflöden, för att möjliggöra en konsistent skattning av dessa. Metoden ger möjlighet att kombinera probe-baserade skattningar av OD- och länkflöden med länkflödesmätningar, mobilnätsdata och tidigare skattningar av OD-matriser från SAMPERS. Den datadrivna nätutläggningen består av två huvudkomponenter, en del som skattar ruttval och en del som propagerar trafik i tid och rum, givet skattat ruttval för en viss tidsperiod. Resultatet från den datadrivna nätutläggningen är en tidsuppdelad fördelningsmatris som fördelar efterfrågan i vägnätet med hjälp av observationer av restid och ruttval som input. Inom ramen för projektet har även ny metod för att skatta avvikelser i resmönster baserat på GPS-baserad probe-data tagits fram.Projektets resultat visar på goda möjligheter att utnyttja storskaliga mobilitetsdata i form av detaljerad GPS-data och mobilnätsdata för att skatta OD- och länkflöden över tid.
|
|
| 48. |
- Gundlegård, David, et al.
(författare)
-
Road Traffic Estimation using Cellular Network Signaling in Intelligent Transportation Systems
- 2009
-
Ingår i: Wireless technologies in Intelligent Transportation Systems. - Hauppauge, NY : Nova Science Publishers. - 9781607415886 - 1607415887 ; , s. 1-33
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In the area of Intelligent Transportation Systems the introduction of wireless communications is reshaping the information distribution concept, and is one of the most important enabling technologies. The distribution of real-time traffic information, scheduling and route-guidance information is helping the transportation management systems in their strive to optimize the system. The communication required to transfer all this information is rather expensive in terms of transmission power, use of the scarce resources of frequencies and also the building of an infrastructure to support the transceivers. By using information that already exists and is exchanged within the infrastructures of the GSM and UMTS networks, a lot of the resource problems are solved. The information that could be extracted from these cellular networks could be used to obtain accurate road traffic information to support real-time traffic information. In this way the cellular networks not only becomes the means to distribute information but also a source of road traffic information.From the analysis made it is obvious that the potential of retrieving valuable road traffic information from cellular systems in a cost efficient way, i.e. by using already existing signalling data, is very high. It has however not been clear what to expect from these systems in terms of accuracy, availability and coverage. In this chapter the basics for this is laid out and discussed in detail. A practical trial has also been performed and the results show clearly the potential as well as the differences in using the GSM compared to the UMTS system. The advantages and drawbacks are discussed and backed up by real measurements from an existing road segment environment. The main advantages of using the existing signalling data, i.e., passive monitoring compared to active monitoring where the terminal sends extra data is discussed and could be summarized in three components, no user acceptance is necessary, no extra signalling is necessary and it does not drain the terminal battery.In the future it is likely that vehicles need to communicate more frequently with each other and with some kind of traffic control centre. This traffic will also be very useful in order to estimate road traffic information using the signalling information obtained from the cellular system. However, the enhanced communication systems will also change traffic patterns in the cellular networks which will affect the potential of estimating road traffic from cellular systems. The evolvement indicates that the terminals will be in active state almost constantly, and hence the updating information will be more frequent and the information more accurate.
|
|
| 49. |
- Gundlegård, David, et al.
(författare)
-
Route Classification in Travel Time Estimation Based on Cellular Network Signaling
- 2009
-
Ingår i: Proceedings of 12th International IEEE Conference on Intelligent Transport Systems (ITSC), October 3-7, St. Louis, USA. - 9781424455201 - 9781424455195 ; , s. 474-479
-
Konferensbidrag (refereegranskat)abstract
- Travel time estimation based on cellular network signaling is a promising technology for delivery of wide area travel times in real-time. The technology has received much attention recently, but few academic research reports has so far been published in the area, which together with uncertain location estimates and environmental dependent performance makes it difficult to assess the potential of the technology. This paper aims to investigate the route classification task in a cellular travel time estimation context in detail. In order to estimate the magnitude of the problem, two classification algorithms are developed, one based on nearest neighbor classification and one based on Bayesian classification. These are then evaluated using field measurements from the GSM network. A conclusion from the results is that the route classification problem is not trivial even in a highway environment, due to effects of multipath propagation and changing radio environment. In a highway environment the classification problem can be solved rather efficiently using e.g., one of the methods described in this paper, keeping the effect on travel time accuracy low. However, in order to solve the route classification task in urban environments more research is required.
|
|
| 50. |
|
|
