CERS - 2021

Permanent URI for this collectionhttp://192.248.9.226/handle/123/17780

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Browsing CERS - 2021 by Author "De Silva, D"

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    item: Conference-Abstract
    An application of a cell transmission model using crowdsourced data for expressway monitoring
    (Department of Civil Engineering, University of Moratuwa, 2021-11) Wijepala, WMRV; De Silva, D; Hettiarachchi, P
    With the increasing traffic congestion in alternative roads, the demand for expressways is increasing rapidly in Sri Lanka. With this increase in demand, traffic management systems are needed for expressways. Deviating from traditional expensive methods of traffic data collection, a more economical and reliable data collection method is needed for developing countries. This study aims to develop and apply a Cell Transmission Model which was first introduced by Carlos F. Daganzo in 1993. The crowdsourced traffic data collected by Google Distance Matrix API has been used. An expressway section was selected and divided into number of sections referred as cells, which were defined with different cell lengths according to the location of the expressway section. The average speed of each cell was collected from Google maps using the MTRADA platform to identify the traffic condition of the selected expressway section, every 5 minutes. The speed data collected were represented in a spatiotemporal graph. Different cell lengths were tested to identify the optimum cell lengths for the model that would allow to identify variations in speed changes. A manual flow data collection was also collected to study the trend between manually collected flow data and speed data collected from M-TRADA. 2 types of cells were used as 200 m and 250 m as normal cells and 400 m and 500 m as doubled cells. Data were collected for both the types simultaneously. According to the comparison done for both the cell types, the normal cells show sufficient information of speed changes than the doubled cells and the cell size has to be at minimum 200 m at the on/off ramps, near sharp curves and near interchanges, while a cell size of 250 m would be sufficient to for cells within the main lanes. This model is more useful for expressways with higher demand. A user interface is proposed for a web application that can be developed using this model for real-time traffic monitoring purposes. Because of the simplicity of the model, even non-expert users will be able to use this web application.
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    item: Conference-Abstract
    Study of the impact to the traffic flow on arterial roads in Colombo due to close distance access roads
    (Department of Civil Engineering, University of Moratuwa, 2021-11) Kaumal, THMM; De Silva, D; Hettiarachchi, P
    The rapid development of Colombo city has resulted in growth in urban traffic. The arterial roads that provide accessibility to Colombo city are experiencing traffic congestions, especially during peak times. The vehicles that enter these arterial roads through closely spaced access roads and exiting vehicles to access roads from the arterial, can be considered as major contributors to causing traffic congestion. This paper analyses how the close-distance access roads affect the traffic flow on arterial roads. A virtual scenario for a 1 km multi-lane arterial road section with separated two lanes in one direction and access roads were connected from the both sides of the arterial road, was created in VISSIM software based on a case study of Galle-Colombo arterial road to replicate local conditions. The flow rate on the arterial road was varied to understand the total delay of the network system and the flow rate of the major arterial roads with varying access road distances. Furthermore, an identification of the combined impact that can occur within the road network was evaluated by defining an index. The index was defined by considering the total delay of the network system and the flow rates of the major arterials. The recommended distance between access roads to arterial roads was identified as a part of the study. It is recommended that access roads may connect with a minimum of 250-275 m distance between their center lines in a 1 km arterial road section for 1000 veh/hr to 4000 veh/hr volume of arterial flow. One of the findings of this study was when future planners designing urban road network systems, access roads should be connected maintaining the above-mentioned distance range between their center lines, regardless of the vehicle volume of arterial roads, to minimize total delay of the road network and maximize the through vehicle flow of arterial roads.