Browsing by Author "Jayasooriya, NK"

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item: Conference-Abstract
Development of a guideline for traffic signals at individual intersections
(Department of Civil Engineering, University of Moratuwa., 2016-08) Jayasooriya, NK; Bandara, JMSJ; Pasindu, HR
With the ever increasing traffic congestion, number of methodologies are developed to initiate sustainable traffic management solutions for the current traffic demand. Rather than going for mega scale infrastructure improvements which would be costly as well as time consuming in short term, it is needed to introduce short term traffic management initiatives to reduce traffic congestion. This has been identified as the research gap, where the main bottleneck of the system has been the delays at signalized intersections. This research identifies the issues with the current traffic signal system, and aims at developing a guideline for traffic signals at individual intersections. It has been identified that the behaviour pattern of the drivers can be categorised as aggressive and peaceful behaviours (Trabia, 1999). Gradinescu (2007) also refers to the parameters needed in identifying the aggressive driving behaviours, which were quite useful in directing the research in producing the methodology. With the aggressive driver behaviour patterns expected in Sri Lanka, the guideline to be developed has been categorised into four; guidelines for geometrical details, phasing arrangements, signal timing, and pedestrians. The data was collected for twelve intersections in Colombo area. Further, the collected data was analysed using VISSIM traffic simulation software, which is already calibrated for the Sri Lankan condition. Further, proper logical arguments are also developed in proving and verifying the guidelines. As for the geometrical details, when no separate right turn is available, it is recommended to use leading green for the right turns in signal design. If the intersection is supposed to have separate right turn lanes, it is recommended to use either lagging green or leading green for the right turns depending on the size of the right turn bay and vehicle volume. Further, with respect to left turns, it is recommended to provide a separate left turn, if the amount of left turns expected are more than the equivalent per lane amount of through movement. With respect to the selection of phasing arrangement, it is suggested to start off every intersection with two phases and use 1300 as the maximum number of right turns plus through volumes that can pass through an intersection during one hour green period. When any phase is violated, it is proposed to split the phase. If separate right turn lane is available, go for leading green for right turns only phase, even when both approaches have right turn lanes. If right turn percentage is significantly smaller, it can be accommodated at the end of Amber. Further, if no separate right turn is available, go for either complete through plus right turn phase for each direction or go for leading green for right turns only phase. As for the guidelines for traffic signal timings, the saturation flow for the Sri Lankan condition should be kept as 2000 vehicles per hour, which is verified through simulations. Further, maximum cycle time should be kept as 150 seconds for 4 phase intersections and 120 seconds for three phase intersections in order to reduce the overall delay for all the phases, except under very special circumstances. With respect to the guidelines for pedestrians, when heavy pedestrian movements are expected, it is proposed to delay the left turns by few seconds. It is also suggested not to provide the pedestrian phase with left turns if the speed of the turning vehicles is more than 15kmph. In conclusion, based on the number of surveys, arguments and simulations conducted the above guidelines are developed in order to reduce the ever increasing traffic congestion that is currently experiencing in Sri Lanka and further research need to be conducted in traffic signal coordination for intersection clusters.
item: Thesis-Full-text
Development of a guideline to coordinate traffic signals for a non-similar intersection cluster
Jayasooriya, NK; Bandara, JMSJ
Development of guidelines to coordinate traffic signals for non-similar intersection clusters Despite the mega scale projects focusing on the long term benefits, proper traffic management initiatives should be introduced and implemented to reduce the unnecessary delays on roads resulting in road user frustration. Traffic signal coordination has been identified as one of the most sustainable solutions, if properly utilized. When it comes to traffic signal coordination, various techniques are available for coordinating similar type intersections. However, when non-similar intersection clusters are encountered, no proper guidelines have been developed for coordination. The research sets out the preliminary requirements essential to be established for the progress of traffic signal coordination. As the first step, selection of an appropriate micro simulation model to support analysis and a procedure to identify and calibrate important input parameters are established. Second, guideline for signal phasing and timing design for individual intersections with fixed time signal timing is proposed. The guidelines are produced for intersections considering geometrical arrangements, traffic signal phasing and timing. Third, guidelines for real time traffic signal designs are produced where the guidelines address the extension of green split for different traffic situations. Finally, the criteria for selecting intersections that should be clustered for traffic signal coordination is established. When clustering, importance of relying on travel time than distance is discussed when developing clustering guidelines. Further, seven basic categories of non-similar intersections based on the intersection geometry and priority directions for green platoon are identified. Based on the analysis, two matrixes are developed for peak period and off-peak period to be utilized by traffic and transportation engineers when non-similar intersections are encountered for traffic signal coordination. The developed guidelines are successfully verified using two case studies, for a selected Baseline road intersection cluster for fixed time traffic signal coordination and Kadawata intersection cluster for real time traffic signal coordination.
item: Conference-Abstract
Development of guidelines for traffic signal coordination for intersection clusters
(Department of Civil Engineering, 2017) Jayasooriya, NK; Bandara, JMSJ; Pasindu, HR
With the ever-increasing traffic congestion, it is needed to initiate sustainable traffic management solutions. There is a need to establish signal design standards taking in to account the latest trends in traffic signal development so that there will be consistency in traffic signal designs and also to make provision to incorporate future coordination and other automation such as monitoring violations and gathering traffic flow information for real time updates. More importantly standardization will minimize user confusion and improve safety at traffic signals and help improving traffic flow and user satisfaction. The congestion issues that are related to signalized intersections are not only inherent to a particular intersection, but rather can be a result of the signal arrangements at nearby intersections. This research identifies the issues with the typical intersection arrangements, and aims at developing a guideline to be followed for traffic signal designs especially when traffic signals are to be coordinated intersection clusters. The necessity of a properly calibrated software for the local condition has been identified as a key component in related literature. VISSIM traffic simulation software was calibrated for the Sri Lankan condition after collecting information from more than 10 intersections in and around Colombo. From the video surveys and manual observations considered, the traffic volumes along with the turning movements, vehicle mix and queue lengths were obtained and compared with the simulated results with an accuracy of ±10. With the calibrated VISSIM software, the guidelines to be followed were developed considering the factors such as; identification of the coordinated phase, determination of individual signal timings for intersections, determination of phase timings for coordinated & non-coordinated directions and optimizing the offsets. The developed guidelines were tested for the Baseline Road intersection cluster and simulation results shows significant delay reductions over xx% for any approach can be achieved in the coordinated directions without adversely affecting the non-coordinated directions.
item: Conference-Full-text
Local construction companies and mega projects: foreign presence in the Sri Lankan construction industry
(Department of Civil Engineering, University of Moratuwa, 2014-03) Jayasooriya, NK; Ekanayake, L; Hettiarachchi, MTP
The Sri Lankan Construction Industry has been booming for the past few years, with the emergence of several mega projects. Mega Projects are currently led by foreign consultancy and construction companies with the foreign aid, and this has caused several concerns in the local construction industry. This research identifies the issues and constraints relating to the local construction companies, when entering into Mega Projects. Further appropriate solutions for the identified issues have also been provided in the research, with the required justification. The research methodology comprises literature review, incorporated with a one to one discussion with the professionals in the industry, including Engineers, Architects,Managers, CEOs, Government Officials, Banking Sector representatives, Foreign Construction Company representatives, and a questionnaire survey carried out with 32 professionals related to the construction Industry. As a conclusion, the research provides the best course of action, for the two major issues identified, with justifications and the research would be a base for the future research to further conduct thorough research on the solutions identified in this research.
item: Conference-Full-text
Local Construction Companies And Mega Projects: Foreign Presence In The Srilankan Construction Industry
(2014-06-10) Jayasooriya, NK; Ekanayake, L
The Sri Lankan Construction Industry has been booming for the past few years, with the emergence of several mega projects. Mega Projects are currently led by foreign consultancy and construction companies with the foreign aid, and this has caused several concerns in the local construction industry. This research identifies the issues and constraints relating to the local construction companies, when entering into Mega Projects. Further appropriate solutions for the identified issues have also been provided in the research, with the required justification. The research methodology comprises literature review, incorporated with a one to one discussion with the professionals in the industry, including Engineers, Architects,Managers, CEOs, Government Officials, Banking Sector representatives, Foreign Construction Company representatives, and a questionnaire survey carried out with 32 professionals related to the construction Industry. As a conclusion, the research provides the best course of action, for the two major issues identified, with justifications and the research would be a base for the future research to further conduct thorough research on the solutions identified in this research