CT-Mapper: Mapping Sparse Multimodal Cellular Trajectories using a Multilayer Transportation Network

Mobile phone data have recently become an attractive source of information about mobility behavior. Since cell phone data can be captured in a passive way for a large user population, they can be harnessed to collect well-sampled mobility information. In this paper, we propose CT-Mapper, an unsupervised algorithm that enables the mapping of mobile phone traces over a multimodal transport network. One of the main strengths of CT-Mapper is its capability to map noisy sparse cellular multimodal trajectories over a multilayer transportation network where the layers have different physical properties and not only to map trajectories associated with a single layer. Such a network is modeled by a large multilayer graph in which the nodes correspond to metro/train stations or road intersections and edges correspond to connections between them. The mapping problem is modeled by an unsupervised HMM where the observations correspond to sparse user mobile trajectories and the hidden states to the multilayer graph nodes. The HMM is unsupervised as the transition and emission probabilities are inferred using respectively the physical transportation properties and the information on the spatial coverage of antenna base stations. To evaluate CT-Mapper we collected cellular traces with their corresponding GPS trajectories for a group of volunteer users in Paris and vicinity (France). We show that CT-Mapper is able to accurately retrieve the real cell phone user paths despite the sparsity of the observed trace trajectories. Furthermore our transition probability model is up to 20% more accurate than other naive models.Comment: Under revision in Computer Communication Journa

The development of a generic step-wise framework for achieving a multimodal platform in a development country environement

Paper presented at the 33rd Annual Southern African Transport Conference 7-10 July 2014 "Leading Transport into the Future", CSIR International Convention Centre, Pretoria, South Africa.With information and technology becoming such a vital commodity in everyday life, it can be argued that informed travellers are the key to successful future transport services. Fortunately, it is recognised that the development of a multimodal transport system is needed in providing integrated traveller information. The relating challenges and the applicable considerations in attaining such an integrated system were researched. Following from this, a generic sequential framework that facilitates multimodal data integration and traveller information as a precursor to a fully integrated multimodal system was developed. In this framework four focus areas, related to the implementation requirements of the application environment considered, were identified. These areas are based on the premise that current technological evolvements need to be exploited in order to breach the missing intelligent link between the various application environments. The focus areas are: 1) the multimodal transport network and the design and modelling thereof, 2) the role of Intelligent Transport Systems (ITS) in achieving a multimodal platform, 3) the need for and the design criteria of a centralised database, and 4) the need for and the travel information requirements of a multimodal Journey Planner (JP). The establishment of such a concise framework (along with its associated steps in attaining multimodal information) will go a long way towards providing the impetus, and eradicate the barriers, in achieving sustainable traveller information services. Ideally, South Africa (SA) will be able to empower a better transport service that spans across the nation’s social barriers.This paper was transferred from the original CD ROM created for this conference. The material was published using Adobe Acrobat 10.1.0 Technology. The original CD ROM was produced by CE Projects cc. Postal Address: PO Box 560 Irene 0062 South Africa. Tel.: +27 12 667 2074 Fax: +27 12 667 2766 E-mail: [email protected]

Leveraging Electronic Ticketing to Provide Personalized Navigation in a Public Transport Network

Public transport networks (PTNs) are difficult to use when the user is unfamiliar with the area she is traveling to, as shown by a user survey that we present in this paper. This is true for both infrequent users (including visitors) and regular users who need to travel to areas with which they are not acquainted. In these situations, adequate on-trip navigation information can substantially ease the use of public transportation and be the driving factor in motivating travelers to prefer it over other modes of transportation. However, estimating the localization of a user is not trivial, although it is critical for providing relevant information. In this paper, we propose the use of an electronic ticketing infrastructure of a PTN operator for positioning within the context of the PTN to give on-trip personalized navigation cues. To our knowledge, this is an innovative contribution that has not been described or deployed, to date, elsewhere.We assess relevant design issues for a modular cost-efficient user-friendly on-trip navigation service that uses position sensors and present the details of a proof-of-concept prototype running in our laboratory.We also present and analyze the results of a user survey on the usefulness of the service and its acceptance by users