Smart transportation systems

Abstract

Akıllı Ulaşım Sistemleri bir süredir araştırmacıların gözde konularından biri olarak çalışılmıştır. Ancak son zamanlarda özellikle kablosuz iletişim sistemlerinde gerçekleşen teknolojik gelişmeler bu çalışmalara son derece büyük bir hız kazandırmıştır. Gün geçtikçe ulaşımı kolaylaşan GPS sistemlerinin araçlarda bulunmaya başlaması ve öte yandan da akıllı cep telefonlarında bu iletişim sistemlerinin entegre halinde son kullanıcıya kadar ulaşması, gerçek zamanlı trafik bilgisi çıkarımını, izlenmesini ve tahmin edilebilmesine olanak tanımıştır.Bu araştırma tezi GPS tabanlı akıllı telefonlar aracılığıyla gerçek zamanlı trafik izleme ve bilgilendirme sistemlerini ve yakın gelecek zamanlı trafik tahminlerini konu almaktadır. Araştırma sonunda on beş dakikalık kısa zamanlı tahminler yürütebilen bir sistemin yanı sıra cep telefonlarından gelen GPS bilgilerini yorumlayabilen bir simülatör geliştirilmiştir.Anahtar kelimeler: Akıllı Ulaşım Sistemleri, Mikroskopik Trafik Simülatörü, Kısa süreli trafik tahmini, GPS tabanlı trafik durumu, Gerçek zamanlı trafik denetimi

Smart or intelligent transportation systems (ITS) have been around for some time. However, they are re-emerging again with the recent advances in wireless communications. This is made possible not only by the technological breakthroughs but also the widespread usage and affordability of the mobile communications based services. Contrary to the longevity of the experiences in ITS technologies, the road traffic in metropolitan areas is far cry from acceptable levels.In order to have a deeper understanding of the aforementioned problem, the state-of-the-art in smart transportation systems has been studied. Many solutions in the literature that are offered by the range of top telecom companies, municipalities, corporations, universities and EU funded projects are reviewed. Communication technologies used in these solutions are discussed. A wide range of simulation tools in the literature are investigated which helped us choosing the right set of simulation tools.The thesis covers the traffic theory background in detail that is investigated in this project. The meaning and the importance of several parameters which are common in all traffic applications such as density, flow, speed, gap, etc. are introduced. The relationship between flow, density and velocity is given and its significance is stated. The thesis also explored the mathematical traffic flow models that are widely mentioned in the traffic engineering discipline and are listed in two categories, namely Macroscopic and Microscopic traffic flow models. A segmented freeway system is simulated with several macroscopic traffic flow models introduced by Lighthill-Whitham-Richards, Payne, Papageorgiou and Daganzo. Some of the simulation results corresponding to Payne and Daganzo?s Cell Transmission Model (CTM) which both utilize the hydrodynamic theory are given in the thesis. The fundamental diagram which is a significant concept that is used in both macroscopic and microscopic levels of traffic flow is studied, as well.The thesis primarily focused on two steps to address the undying issue of recent decades which has lately become even more irritating. The first step described our efforts to construct and introduce a short-term prediction system. A simple yet effective simulation tool called CTMsim is presented. Two different case studies modeling a portion of TEM freeway ranging from Kavacık to Maslak have been carried out to demonstrate the abilities of the tool. Firstly, a traffic accident scenario is depicted and its effects both visually and statistically are displayed in the area of influence. In addition to it, second scenario interpreted and portrayed the prediction of the traffic states fifteen minute ahead of time which resulted in a slight difference from the real-time calculation. Briefly, the tool has been able to capture the traffic dynamics and present promising results.The second step is comprised of presenting a real-time traffic monitoring system. On this sense, a simulator named BAU Traffic Simulator that is integrated with a smartphone application called TTraffic is developed from the scratch. The tool achieved to dynamically interpret the outputs of the client (android app) and represent the system in real-time. The outputs of the simulator can be fetched by the clients in order to get real-time traffic information, and hence calculate a dynamic routing plan to get to the destination within the possible minimum time. All analyses carried out during the development phase are presented in the thesis. Lastly three traffic scenarios simulating Regular Traffic, Free Flow Traffic, and Traffic Accident conditions are presented and analyzed thoroughly.Keywords: Intelligent Transportation Systems, Microscopic Traffic Simulator, Traffic Prediction, GPS-based Traffic Estimation, Real-time Traffic monitoring