Browsing by Author "Withana, S"

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item: Conference-Full-text
Analyzing the necessity of adaptive traffic control systems (ATCS) in Sri Lanka
(Sri Lanka Society of Transport and Logistics, 2024) Samarasinghe, N; Amarasingha, N; Withana, S; Gunaruwan, T. L.
Traffic congestion emerges as a significant concern, further amplified by the increasing population and urbanization rates. The rise in vehicular and pedestrian traffic contributes significantly to traffic congestion, exacerbating issues related to mobility, sustainability, and environmental health. Implementing effective traffic management strategies is critical for mitigating these challenges. The objective of this study is to enhance the performance of existing Traffic Control Systems and to analyze the coordination of junctions using micro stimulation software. Using this microsimulation software, it is possible to analyze traffic video footage from the junction under study and extract important traffic flow data for analysis. Despite the availability of numerous studies, a significant gap remains in effectively using simulation models to address congestion issues in Sri Lanka. This study seeks to close this gap by investigating the most effective use of microsimulation software for traffic management in Sri Lanka.
item: Conference-Abstract
Development of decision framework for dynamic signal timing design
(Department of Civil Engineering, University of Moratuwa, 2021-10) Withana, S; Perera, L; Bandara, S; Perera, HLK
The traditional fixed time traffic signal systems use a static signal timing or in other words, a pre designed signal timing developed based on past traffic data. The signal timing design assumes the traffic levels to be similar for a given time period, but the traffic levels are highly fluctuating and dynamic in reality. Therefore, the next step in traffic signal timing designs is the dynamic designs where the timing will be varied in real time. This type of signal time designs will be mainly used in Adaptive Traffic Signal Systems which are designed to operate using real time information. A dynamic signal timing design requires a decision framework for real time operations and information management. Therefore, this study is aimed at development of a decision framework to minimize the delay time and to maximize the traffic flow in an intersection under unsaturated conditions. Analyzing many parameters used in literature, two main parameters were considered in this study, namely, critical lane flow and stop delay. Impact from pedestrians are incorporated by using the pedestrian delay time. The behavioural patterns identified in the individual parameters, when releasing traffic during the green time period in an intersection, was used to develop the framework. The behaviours of individual parameters in real scenarios were shown deviated results from theoretical studies mainly due to mixed traffic conditions. Motorcycles have contributed significantly for such deviation and as well as the capacity of the intersection. The decision framework was developed by integrating the individual parameters and their limits to communicate among phases in the traffic cycle. The cycle time was kept as a variable in the decision framework. This decision framework was simulated using PTV VISSIM software to observe unsaturated conditions in Piliyandala- Maharagama bypass Junction as a case study. The simulation results were obtained for different unsaturated flow conditions. They were in line with the expected outcomes. The flow through the intersection was slightly increased and average delay time was reduced slightly
item: Conference-Full-text
A Study on SSD Aware Scan Operation Optimization in PostgreSQL Database
Nakandala, S; Withana, S; Kumarasiri, D; Jayawardena, H
Cost functions used by query optimizers in database systems are built around the properties of conventional hardware technologies like spin type hard disk drives. But with the rapid development in storage technology several new technologies have emerged to overcome the limitations in conventional storage media. One such storage technology is flash storage type which belongs to the broader category of SSDs (Solid State Devices). In this paper we discuss a study done to optimize scan operation performance in PostgreSQL database running on flash storage media by changing the random block transfer cost parameter to a suitable value.