1,179 research outputs found
Development of origin–destination matrices using mobile phone call data
In this research, we propose a methodology to develop OD matrices using mobile phone Call Detail Records (CDR) and limited traffic counts. CDR, which consist of time stamped tower locations with caller IDs, are analyzed first and trips occurring within certain time windows are used to generate tower-to-tower transient OD matrices for different time periods. These are then associated with corresponding nodes of the traffic network and converted to node-to-node transient OD matrices. The actual OD matrices are derived by scaling up these node-to-node transient OD matrices. An optimization based approach, in conjunction with a microscopic traffic simulation platform, is used to determine the scaling factors that result best matches with the observed traffic counts. The methodology is demonstrated using CDR from 2.87 million users of Dhaka, Bangladesh over a month and traffic counts from 13 key locations over 3 days of that month. The applicability of the methodology is supported by a validation study
A Hierarchical Approach for Investigating Social Features of a City from Mobile Phone Call Detail Records
Cellphone service-providers continuously collect Call Detail Records (CDR) as
a usage log containing spatio-temporal traces of phone users. We proposed a
multi-layered hierarchical analytical model for large spatio-temporal datasets
and applied that for the progressive exploration of social features of a city,
e.g., social activities, relationships, and groups, from CDR. This approach
utilizes CDR as the preliminary input for the initial layer, and analytical
results from consecutive layers are added to the knowledge-base to be used in
the subsequent layers to explore more detailed social features. Each subsequent
layer uses the results from previous layers, facilitating the discovery of more
in-depth social features not predictable in a single-layered approach using
only raw CDR. This model starts with exploring aggregated overviews of the
social features and gradually focuses on comprehensive details of social
relationships and groups, which facilitates a novel approach for investigating
CDR datasets for the progressive exploration of social features in a
densely-populated city
Developing Travel Behaviour Models Using Mobile Phone Data
Improving the performance and efficiency of transport systems requires sound decision-making supported by data and models. However, conducting travel surveys to facilitate travel behaviour model estimation is an expensive venture. Hence, such surveys are typically infrequent in nature, and cover limited sample sizes. Furthermore, the quality of such data is often affected by reporting errors and changes in the respondents’ behaviour due to awareness of being observed. On the other hand, large and diverse quantities of time-stamped location data are nowadays passively generated as a by-product of technological growth. These passive data sources include Global Positioning System (GPS) traces, mobile phone network records, smart card data and social media data, to name but a few. Among these, mobile phone network records (i.e. call detail records (CDRs) and Global Systems for Mobile Communication (GSM) data) offer the biggest promise due to the increasing mobile phone penetration rates in both the developed and the developing worlds. Previous studies using mobile phone data have primarily focused on extracting travel patterns and trends rather than establishing mathematical relationships between the observed behaviour and the causal factors to predict the travel behaviour in alternative policy scenarios.
This research aims to extend the application of mobile phone data to travel behaviour modelling and policy analysis by augmenting the data with information derived from other sources. This comes along with significant challenges stemming from the anonymous and noisy nature of the data. Consequently, novel data fusion and modelling frameworks have been developed and tested for different modelling scenarios to demonstrate the potential of this emerging low-cost data source.
In the context of trip generation, a hybrid modelling framework has been developed to account for the anonymous nature of CDR data. This involves fusing the CDR and demographic data of a sub-sample of the users to estimate a demographic prediction sub-model based on phone usage variables extracted from the data. The demographic group membership probabilities from this model are then used as class weights in a latent class model for trip generation based on trip rates extracted from the GSM data of the same users. Once estimated, the hybrid model can be applied to probabilistically infer the socio-demographics, and subsequently, the trip generation of a large proportion of the population where only large-scale anonymous CDR data is available as an input. The estimation and validation results using data from Switzerland show that the hybrid model competes well against a typical trip generation model estimated using data with known socio-demographics of the users. The hybrid framework can be applied to other travel behaviour modelling contexts using CDR data (in mode or route choice for instance).
The potential of CDR data to capture rational route choice behaviour for long-distance inter-regional O-D pairs (joined by highly overlapping routes) is demonstrated through data fusion with information on the attributes of the alternatives extracted from multiple external sources. The effect of location discontinuities in CDR data (due to its event-driven nature), and how this impacts the ability to observe the users’ trajectories in a highly overlapping network is discussed prompting the development of a route identification algorithm that distinguishes between unique and broad sub-group route choices. The broad choice framework, which was developed in the context of vehicle type choice is then adapted to leverage this limitation where unique route choices cannot be observed for some users, and only the broad sub-groups of the possible overlapping routes are identifiable. The estimation and validation results using data from Senegal show that CDR data can capture rational route choice behaviour, as well as reasonable value of travel time estimates.
Still relying on data fusion, a novel method based on the mixed logit framework is developed to enable the analysis of departure time choice behaviour using passively collected data (GSM and GPS data) where the challenge is to deal with the lack of information on the desired times of travel. The proposed method relies on data fusion with travel time information extracted from Google Maps in the context of Switzerland. It is unique in the sense that it allows the modeller to understand the sensitivity attached to schedule delay, thus enabling its valuation, despite the passive nature of the data. The model results are in line with the expected travel behaviour, and the schedule delay valuation estimates are reasonable for the study area.
Finally, a joint trip generation modelling framework fusing CDR, household travel survey, and census data is developed. The framework adjusts the scaling factors of a traditional trip generation model (based on household travel survey data only) to optimise model performance at both the disaggregate and aggregate levels. The framework is calibrated using data from Bangladesh and the adjusted models are found to have better spatial and temporal transferability.
Thus, besides demonstrating the potential of mobile phone data, the thesis makes significant methodological and applied contributions. The use of different datasets provides rich insights that can inform policy measures related to the adoption of big data for transport studies. The research findings are particularly timely for transport agencies and practitioners working in contexts with severe data limitations (especially in developing countries), as well as academics generally interested in exploring the potential of emerging big data sources, both in transport and beyond
Big Data Techniques to Improve Learning Access and Citizen Engagement for Adults in Urban Environments
This presentation explores the emerging concept of ‘Big Data in Education’ and introduces
novel technologies and approaches for addressing inequalities in access to participation and
success in lifelong learning, to produce better life outcomes for urban citizens. It introduces
the work of the new Urban Big Data Centre (UBDC) at the University of Glasgow, presenting
a case study of its first data product – the integrated Multimedia City Data (iMCD) project.
Educational engagement and predictive factors are presented for adult learners, and older
adult learners, in a representative survey of 1500 households. This was followed up with
mobility tracking data using GPS data and wearable camera images, as well as one year’s
worth of contextual data from over one hundred web sources (social media, news, weather).
The chapter introduces the complex dataset that can help stakeholders, academics, citizens
and other external users examine active aging and citizen learning engagement in the
modern urban city, and thus support the development of the learning city. It concludes with a call for a more three-dimensional view of citizen-learners’ daily activity and mobility, such
as satellite, mobile phone and active travel application data, alongside administrative data
linkage to further explore lifelong learning participation and success. Policy implications are
provided for addressing inequalities, and interventions proposed for how cities might
promote equal and inclusive adult learning engagement in the face of continued austerity
cuts and falling adult learner numbers
Human Mobility Patterns for Different Regions in Myanmar Based on CDRs Data
Sustainable urban and transportation planning depends greatly on understanding human mobility patterns in urban area. Myanmar is one of the developing countries in ASEAN. It develops more rapidly as compare past years due to its international trade policy change and faces serious traffic problem in major cities. To solve these problem, human mobility pattern need to know for improvement. Therefore, this paper focuses to analyze different human mobility patterns for the different regions in Myanmar by using Call Detail Records (CDRs) Data. Such studies could be useful for creating transport model of mobility pattern. The numbers of trip generated are obtained by using CDRs over seven days period. CDRs of each region can be used to generate trip numbers of townships within certain time frame and time windows. In this study, average distance travelled, preferred days of long distance users and human mobility patterns at different times of weekdays and weekends in Yangon and Mandalay were analyzed. People living in Yangon area are generally more travelled than Mandalay on weekdays and weekends. The results indicated the similarities and differences in mobility patterns for both cities. This information is very useful for transport planning and future transportation developments
Identifying Hidden Visits from Sparse Call Detail Record Data
Despite a large body of literature on trip inference using call detail record
(CDR) data, a fundamental understanding of their limitations is lacking. In
particular, because of the sparse nature of CDR data, users may travel to a
location without being revealed in the data, which we refer to as a "hidden
visit". The existence of hidden visits hinders our ability to extract reliable
information about human mobility and travel behavior from CDR data. In this
study, we propose a data fusion approach to obtain labeled data for statistical
inference of hidden visits. In the absence of complementary data, this can be
accomplished by extracting labeled observations from more granular cellular
data access records, and extracting features from voice call and text messaging
records. The proposed approach is demonstrated using a real-world CDR dataset
of 3 million users from a large Chinese city. Logistic regression, support
vector machine, random forest, and gradient boosting are used to infer whether
a hidden visit exists during a displacement observed from CDR data. The test
results show significant improvement over the naive no-hidden-visit rule, which
is an implicit assumption adopted by most existing studies. Based on the
proposed model, we estimate that over 10% of the displacements extracted from
CDR data involve hidden visits. The proposed data fusion method offers a
systematic statistical approach to inferring individual mobility patterns based
on telecommunication records
Measuring commuting and economic activity inside cities with cell phone records
We show how to use commuting flows to infer the spatial distribution of income within a city. A simple workplace choice model predicts a gravity equation for commuting flows whose destination fixed effects correspond to wages. We implement this method with cell phone transaction data from Dhaka and Colombo. Model-predicted income predicts separate income data, at the workplace and residential level, and by skill group. Unlike machine learning approaches, our method does not require training data, yet achieves comparable predictive power. We show that hartals (transportation strikes) in Dhaka reduce commuting more for high model-predicted wage and high skill commuters.First author draf
Advances in crowd analysis for urban applications through urban event detection
The recent expansion of pervasive computing technology has contributed with novel means to pursue human activities in urban space. The urban dynamics unveiled by these means generate an enormous amount of data. These data are mainly endowed by portable and radio-frequency devices, transportation systems, video surveillance, satellites, unmanned aerial vehicles, and social networking services. This has opened a new avenue of opportunities, to understand and predict urban dynamics in detail, and plan various real-time services and applications in response to that. Over the last decade, certain aspects of the crowd, e.g., mobility, sentimental, size estimation and behavioral, have been analyzed in detail and the outcomes have been reported. This paper mainly conducted an extensive survey on various data sources used for different urban applications, the state-of-the-art on urban data generation techniques and associated processing methods in order to demonstrate their merits and capabilities. Then, available open-access crowd data sets for urban event detection are provided along with relevant application programming interfaces. In addition, an outlook on a support system for urban application is provided which fuses data from all the available pervasive technology sources and finally, some open challenges and promising research directions are outlined
Dynamic, interactive and visual analysis of population distribution and mobility dynamics in an urban environment using the mobility explorer framework
© 2017 by the authors. This paper investigates the extent to which a mobile data source can be utilised to generate new information intelligence for decision-making in smart city planning processes. In this regard, the Mobility Explorer framework is introduced and applied to the City of Vienna (Austria) by using anonymised mobile phone data from a mobile phone service provider. This framework identifies five necessary elements that are needed to develop complex planning applications. As part of the investigation and experiments a new dynamic software tool, called Mobility Explorer, has been designed and developed based on the requirements of the planning department of the City of Vienna. As a result, the Mobility Explorer enables city stakeholders to interactively visualise the dynamic diurnal population distribution, mobility patterns and various other complex outputs for planning needs. Based on the experiences during the development phase, this paper discusses mobile data issues, presents the visual interface, performs various user-defined analyses, demonstrates the application's usefulness and critically reflects on the evaluation results of the citizens' motion exploration that reveal the great potential of mobile phone data in smart city planning but also depict its limitations. These experiences and lessons learned from the Mobility Explorer application development provide useful insights for other cities and planners who want to make informed decisions using mobile phone data in their city planning processes through dynamic visualisation of Call Data Record (CDR) data
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