Delay-based Performance Analyses Of Four-legged Signalized Intersections: A Case Study

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2014Önümüzdeki çalışmada ortalama taşıt başına gecikme seç timiz örnek kavşakların çalışma durumunu yansıtmak için kullanılmaktadır.  Gecikme sürücünün arzu ettiği ve gerçekte yaşadığı yolculuk zamanların arasındaki fark olarak tanımlanır. Bu çalışmanın yapılmasında İstanbul’daki Pendik mahallesinde olan iki dört kollu ışıklı kavşak örnek olarak alınmıştır. Biran önce 7:00-10:00, 12:00-14:00 ve 16:30-19:30 Saatlar arasında kamera ile çekim yapılmıştır. Sonra kamera görüntüleri bilgisayar ortamına aktarılıp ve bunlar üzerinden türel ayrımı yaparak 15’r dakikalık zaman dilimleri halinde her yöne giden trafik hacimleri belirlenmiştir. Bu bilgiler ışığında her kol da ve her akım için en fazla taşıt bulunan saat zirve saat olarak tanımlanmıştır. Sonra, zirve saat faktörü (ZSF) zirve saat hacmin akım değerine bölerek her kol için elde edilmişte.  Zirve saat faktörün kullanarak her kol için düzeltilmiş hacim hesaplanmıştır. Sonunda bu akım değerleri VISSIM’e aktarılıp ve oluşturdumuz benzetim model bu verilere göre kalibre edilmiştir. Kalibrasiyon süreci modelin gerçeke yakın çalışmasın sağlar ve sonuçta elde edilmiş sonuçlara daha fazla güvenile bilir. Bu çalışmada kalibrasiyon araç sayısına göre tüm kollarda yapılıp ve benzetim modelin gerçeğe ne kadar yaklaştığı GEH değeri ile ölçülmektedir. Benzetim kalibrasiyonu yapıldıktan sonra elde edilen akım değerleri kayıt edilip ve bu çalışmanın tüm yöntemlerinde akım değeri olarak kullanılmaktadır.  VISSIM’de elde edilen veriler ışığında Amerikan (HCM) ve Avusturalya (Akçelik) yöntemlerin kullanarak seçtimiz kavşakların performansı belirlrnmektedir. Aslında genel Avustralya ve HCM yöntemleri VISSIM’in dinamik yöntem ile karşılaştırılmıştır. Sonunda bu yöntemlerden elde edilen sonuçlar birbiri ile karşılaştırılmış ve olası nedenler tartışılmıştır.For conducting this study, two for-legged signalized intersections in Pendik area of Istanbul city were designated as case studies. Traffic flows obtained using camera recording method at sites between 7:00-10:00, 12:00-14:00 and 16:30-19:30 time periods. Then, all the recordings were transformed to the computer and the frequency of different types of vehicles in 15-min periods were counted and tabulated with respect to their travel directions. Subsequently, on each approach and for each travel direction, the hour during which maximum traffic volume occurs was designated as its peak hour. In continue, peak hour factors (PHF) were calculated for each approach by dividing the peak hour volume to the flow rate of that approach. Using this PHF factor the adjusted flow rate was computed for each lane group.  Finally, these flow rates were transformed to the VISSIM, and the established models were calibrated to replicate the field situation subsequently, and the final volumes yielded by the VISSIM after calibration process were used as this study flow rate inputs in all methods. Employing these data the performance of case studies were estimated applying Australian (Akcelik) and USA (HCM 2000) methods as well as PTV VISSIM software. That is, the conventional methods of Australian and USA were compared with dynamic method of VISSIM. Finally, the results derived from these four methods were analyzed and differences between these methods and possible reasons were discussed.Yüksek LisansM.Sc

Development and evaluation of models for autonomous shared mobility-on-demand systems

This paper presents a research framework for the development and evaluation of new methods to provide urban transport that offer efficient, affordable and flexible trips while reducing reliance on private vehicle use. Specifically, the paper outlines a research project which aims to demonstrate novel uses of low carbon mobility solutions driven by disruptive forces which are changing the mobility landscape and providing consumers with more choices to meet their transport needs. These forces include vehicle electrification, automated self-driving and on-demand shared mobility services. The focus of this research is on understanding the factors influencing the acceptance and demand for mobility under these emerging forces, development of models for understanding the demand for travel in the age of connected mobility, and assessing their impacts particularly under scenarios of autonomous or self-driving on-demand shared mobility. The successful completion of this research will result in the development of rigorous models that provide a better understanding of the likely reduction in carbon footprint which these trends are likely to achieve for future urban mobility. This paper also provides some initial results from a pilot study on a small road network. The results showed that autonomous mobility reduced the number of required vehicles by more than 40% while still meeting the same demand for travel on the road network, compared to a base scenario with conventional cars only. The autonomous mobility also reduced the need for car parking space (by around 58% compared to the base-case scenario). Such an impact has a clear influence on urban form in our cities and could free up a substantial amount of land and space that can be used for other purposes. However, the simulation also showed that the total vehicle-kilometres travelled by the autonomous vehicles increased because the vehicles needed to reposition. Finally, the paper describes the remaining challenges that need to be overcome in this research, and outlines the next steps to achieve the desired outcomes