Traffic estimation, sensing, and control in work zone environments

This dissertation is motivated by practical safety and mobility concerns in freeway work zones. Smart work zone systems are composed of sensors, communication technologies, and data processing algorithms that are used to monitor and disseminate critical information such as congestion and severe slowdowns. Though a large number of smart work zone technologies have been deployed, many systems are still not well understood in terms of the technologies employed and the overall performance of the system. To address this gap, this dissertation develops theoretical, algorithmic, and practical contributions to the improvement of smart work zone systems from the aspects of traffic estimation, sensing, and control. To understand the impact of the sensing technologies and estimation algorithms, several hundred combinations of sensor network configurations and traffic estimation algorithms are assessed in a traffic micro simulator calibrated with data from a work zone in Illinois. The simulations allow the importance of the sensor type and spacing, the accuracy of individual sensors, and the estimation algorithm to be quantified. It is identified that the spacing of sensors is an important factor for improving the traffic estimation accuracy, and significant improvements can be obtained through traffic estimation algorithms relying on nonlinear filtering techniques. When less sophisticated (but more commonly deployed) algorithms are used, dense sensor deployments offer the most improvement in traffic estimation accuracy. Unfortunately, most existing traffic sensor technologies in work zones are expensive, which prohibits dense deployments. Motivated by this result, a low cost and energy efficient work zone traffic sensor is proposed relying on passive infrared sensing. The sensor hardware and software is developed to assess the potential of passive infrared technologies for traffic monitoring. To detect vehicles and estimate vehicle speeds from the passive infrared sensor, unsupervised machine learning algorithms are developed. Field experiments show that the developed sensors are capable of achieving approximately 3% vehicle detection errors and 3 mph root mean square error for the estimated vehicle speeds aggregated in one-minute intervals. Finally, to improve mobility in work zones, the problem of traffic control in work zones is examined. The traffic dynamics on each link in the work zone is modeled using the Hamilton Jacobi Partial Differential Equation (PDE) augmented with flow constraints at the junctions. A model predictive controller is designed which solves the control problem as a single convex program. The numerical scheme used in the algorithm efficiently computes the evolution of traffic dynamics on the network without the discretization of the PDE, and provides a natural framework for a variety of optimal traffic control problems. The effectiveness of the framework is validated in a microsimulation environment

AIS in Australia: UTAUT application & cultural implication

Although the diffusion of information technologies has been widely considered in the Australian context, very few studies seem to have focus on the adoption and diffusion of information systems among individual accountants. This research investigates factors affecting the use of Accounting Information Systems (AIS) by Australian accounting practitioners. The Unified Theory of Acceptance and Use of Technology model by Venkatesh et al. (2003) is adopted to investigate this issue. The model is extended by integrating the national culture theory by Hall (1973), with an emphasis on culture and communication. Data were collected from 190 accountants in Australia. The data collected were analysed using Structural Equation Modeling in association with the Partial Least Squares technique. The results show that performance expectancy, effort expectancy, facilitating condition and low context communication characterising the Australian culture positively influence behavioral intention and utilisation of AIS

Liminality and festivals - Insights from the East

This research extends our knowledge of liminality through investigating how the liminal experiences of festival-goers are constructed in a Chinese music festival context. The research employs a multi-site data collection approach undertaking field observations and 68 in-depth semi-structured interviews at seven music festivals across three years. The study contributes to the theoretical development of a liminality framework by providing empirical evidence of the nature of liminality. It extends our understanding of event tourist experiences by highlighting the development and role of three types of communitas and identifying six stages within a rite of passage. The resulting multifaceted coexistence of liminal behaviours and identity with everyday routine life provides a new approach to the critical understanding of the role of liminality