Browsing by Author "Rajapaksha, G"

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    An approach to identify bottlenecks in road networks using travel time variations: a case study in the city of Colombo and suburbs
    (IEEE, 2020-07) Thilakshan, T; Rajapaksha, G; Bandara, S; Edussooriya, C; Weeraddana, CUS; Abeysooriya, RP
    Bottlenecks in road networks are the main contributing factor in terms of traffic congestion in urban areas and thus, identification of bottlenecks and introduction of relevant remedies are important in easing the traffic congestion especially in the case of developing countries where funding for new transport infrastructure projects is a major factor of concern. This study discusses on identification of bottlenecks using crowdsource real- time travel time data which is more effective in terms of collection and usage in analysis. The usual travel time collection process is thus replaced by using Google Maps API matrix. Shortest travel time and travel distance paths among main origin and destinations are analyzed and the contrast in shortest distance path not being the shortest travel time path brings an important consideration of the reasons associated mainly due to presence of bottlenecks which needs to be identified and rectified for better road user experience. After a macro level approach in the identification process, certain transportation indices such as Congestion Index, Delay Rate Index and Travel Rate Ratio in a meso and micro level analysis perspective are utilized to ensure the identification of critical bottlenecks along minimum distance paths in the road network of main roads.
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    Assessment of measure of effectiveness of two-lane roads under non-homogeneous traffic conditions
    (IEEE, 2021-07) Rajapaksha, G; Bandara, S; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
    One aspect of measure of effectiveness of two-lane road is freedom of passing manoeuvre. Highway Capacity Manual (HCM) use percent time spent following (PTSF) as a measure to evaluate freedom of passing manoeuvre. Several researchers found that PTSF is incompatible with nonhomogeneous traffic conditions. Different follower-related performance measures, namely, percent followers (PF), follower density (FD) and the number of followers as a proportion of capacity (NFPC), Percent Impeded (PI), have been evaluated and a new measure called Stripped Based Follower Density (SFD) is introduced considering driving behavior of heterogeneous traffic condition. Data is collected from 12 two lane roads in Sri Lanka using a 2.5 second time gap suggested as driver perception -reaction time by AASSHTO to identify followers. LOS threshold values for SFD were introduced using K-mean clustering technique and compared with HCM LOS threshold.