Abstract: The so-called urban heat island (UHI) is an anthropogenic effect of an elevated temperature level in urban areas compared to their surrounding. While the many causes of the UHI have been identified in the past, the magnitude of each component strongly depends on the individual city and its geography. In most cases a UHI is a thread, resulting in heat-related stress and health issues, higher costs for air-conditioning and cooling, and loss of quality of urban living in general. Based on the experience and research done in the tropical megacity of Singapore, where the UHI results in elevated temperature levels of up to 8 degree Celsius, several barriers and challenges in tackling the problem have been identified: 1) lack of data, information, and knowledge; 2) missing interdisciplinary and transdisciplinary collaboration; 3) synthesis of various modeling approaches; and last but not least 4) computational challenges. In addressing all four points above we suggest an approach based on combining top-down with bottom-up models, which has been introduced by the Future Cities Lab of the Singapore-ETH Center in 2012, and further developed known as the Cooler Calmer Singapore project. The past, current, and future research within the project and the collaboration to the outside will be demonstrated. Before the UHI of Singapore can be fought, the complex problem needs to be fully understood. Our research shall enable this task.

Abstract: Increasing availability of floating car data both historic in the form of trajectory data-sets and real-time in the form of continuous data stream paves the way for data driven traffic simulations. While historic data-sets can be used to construct spatiotemporal models of different roads, the continuous data streams from probe vehicles can be used for purposes such as current traffic-state estimation, incident detection and predicting short term evolution of traffic. A service which incorporates the aforementioned features will be invaluable for advanced traffic management and information services. In this paper we present a thorough analyses of using probe vehicles for reconstructing traffic state in real time, by employing detailed agent based microscopic traffic simulations of several scenarios on real world expressway.

Abstract: Due to recent advanced communication possibilities between traffic infrastructure, vehicles and drivers, the optimization of traffic lights control can be approached in novel ways. At the same time, this may introduce new unexpected dynamics in transportation systems. Our research aims to determine how drivers and traffic lights systems interact and influence each other when they are informed one about another's behaviour. In order to study this, we developed an agent based model to simulate transportation systems with static and dynamic traffic lights and drivers using information about the traffic lights behaviour. Experiments reveal that the system's performance improves when a bigger share of drivers receive information for both static and dynamic traffic lights systems. This performance improvement is due to drivers managing to avoid stopping at red light rather them adapting their speed to different distances to the traffic lights systems. Additionally, it is demonstrated that the duration of the fixed phases also influences the performance when drivers use speed recommendations. Moreover, the results show that dynamic traffic lights can produce positive effects for roads with high speed limits and high traffic intensity, while in the rest of the cases static control is better. Our findings can be used for building more efficient traffic lights systems.

Abstract: Implementation of Vehicle-to-everything (V2X) communication technologies, for traffic management, has been envisioned to have a plethora of far-reaching and useful consequences. However, before any hardware/software infrastructure can be developed and implemented, a thorough phase of testing is warranted. Since actual vehicles and traffic conditions cannot be physically re-constructed, it is imperative that accurate simulation tools exist in order to model pragmatic traffic scenarios and communication amongst the participating vehicles. In order to realize this need of simulating V2X technology, we have created an integrated simulation environment that combines three software packages, VISSIM (traffic modelling), MATLAB (traffic management applications) and NS3 (Communication network simulation). The combination of the simulators, has been carried out in a manner that allows on-line exchange of data amongst them. This enables one to visualize whether a traffic management algorithm creates the desired effect and also the efficacy of the communication protocol used. In order to test the simulator, we have modelled the Green Light Optimized Speed Advisory (GLOSA) application, whose objective is communication of the present traffic signal phase information to oncoming vehicles using a transmitting unit installed on the signal itself. This information will allow the vehicles to calculate the desired speeds necessary to cross the relevant intersection without stopping. Therefore, a "Green Wave" can be created for all vehicles without the need to coordinate traffic signal timers, which can be rather complex in a multiple intersection traffic corridor.