Simulation, optimization and visualization of transportation data

Overview & Synopsis

Today all major metropolises in France, Europe and the rest of the world suffer from severe problems of congestion and saturation of infrastructures, which concern both individual and public transport. Current transportation systems are reaching capacity limits and appear unable to absorb increases in passenger flows in the future. The transport of the future is part of the various so-called Smart City initiatives and should be ”intelligent”, that is to say not only react to the demands but anticipate them, relying on the data exchanged between the end user and the information system of transportation operators.Within this context, one of the main challenges is the creation of appropriate methodologies for analysis of geo-localized transport data for instantaneous storage, analysis, management and dissemination of massive (typically thousands of instant geo-localizations , with a refresh rate of the order of a few seconds) data flows. The related algorithms must be capable of managing event lists of several tens of minutes to calculate real trajectories, instantaneous occupations, traffic lights changing cycles as well as vehicular traffic flow forecasts.In this thesis, we address two different issues related to this topic.A first contribution concerns the optimization of the traffic lights systems. The objective is to minimize the total journey time of the vehicles that are present in a certain part of a city. To this purpose, we propose a PSO (Particle Swarm Optimization) technique. The experimental results obtained show that such an approach makes it possible to obtain significant gains (5.37% - 21.53%) in terms of global average journey time.The second part of the thesis is dedicated to the issue of traffic flow prediction. In particular, we focus on prediction of the bus arrival time in the various bus stations existent over a given itinerary. Here, our contributions first concern the introduction of a novel data model, so-called TDM (Traffic Density Matrix), which captures dynamically the situation of the traffic along a given bus itinerary. Then, we show how different machine learning (ML) techniques can exploit such a structure in order to perform efficient prediction. To this purpose, we consider first traditional ML techniques, including linear regression and support vector regression with various kernels. The analysis of the results show that increasing the level of non-linearity can lead to superior results. Based on this observation, we propose various deep learning techniques with hand-crafted networks that we have specifically adapted to our objectives. The proposed approach include recurrent neural networks, LSTM (Long Short Time Memory) approaches, fully connected and convolutional networks. The analysis of the obtained experimental results confirm our intuition and demonstrate that such highly non-linear techniques outperform the traditional approaches and are able to deal with the singularities of the data that in this case correspond to localized traffic jams that globally affect the behavior of the system.Due to the lack of availability of such highly sensitive type of geo-localized information, all the data considered in our experiments has been produced with the help of the SUMO (Simulation of Urban Mobility) microscopic simulator. We notably show how SUMO can be exploited to construct realistic scenarios, close to real-life situations and exploitable for analysis purposes.Interpretation and understanding the data is of vital importance, nevertheless an adequate visualization platform is needed to present the results in a visually pleasing and understandable manner. To this purpose, we finally propose two different visualization application, a first one dedicated to the operators and the second one to clients. To ensure the deployment and compatibility of such applications on different devices (desktop PCs, Laptops, Smartphones, tablets…) a scalable solution is proposed.