Travel Time Reliability to Evaluate the Performance of Bus Transport Service Along Major Corridors of Addis Ababa City
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Date
2024-10
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Addis Ababa University
Abstract
Travel time reliability (TTR) has been progressively considered an important measure of the performance of the transportation system. TTR is related to the travel experience and is significant to both users and public transport operators. The study investigates bus travel time reliability along major corridors in Addis Ababa, focusing on identifying key factors that influence reliability and proposing actionable improvements. As urbanization drives increased travel demand, public transport systems, particularly buses, are crucial for sustainable mobility. However, challenges such as traffic congestion, inadequate infrastructure, and unreliable services undermine their effectiveness. The main objective of the study is to characterize and develop predictive analysis of bus travel time reliability for a major corridors in Addis Ababa: Corridor 1 (Mexico to Haile Garment Square), Corridor 2 (Kara Kore to Wabi Shebelle Hotel/Mexico), and Corridor 3 (Megenagna to Derartu Square). The study aims to assess bus TTR, identify influencing factors and their impact on TTR of bus transport, and assess TTR from the users' perspective. A descriptive research method was used, combining quantitative and qualitative research approaches. Primary and secondary data were collected, including AVL (O D based) system data for travel time estimation and TTR modeling, as well as user perspectives gathered through interviews. A multiple linear regression model was applied to identify factors affecting bus TTR. Users were purposively selected at bus waiting stations along the corridors. Index based analysis with the planning time index was used to measure the reliability of the study corridors, and travel time pattern revealing that peak hours (AM(6:30 9:30) and PM(4:00 7:30)), and weekdays (Monday, and Friday) were particularly unreliable. The regression model fit, using those variables, yielded adjusted R squared values of 0.79 (79%) without interaction model and 0.8 (80%) with interaction for the study corridors. The analysis indicates that segment length, travel speed, dwell time, bus lanes, number of intersections, number of bus stops, bus frequency, time of the day, and day of the week are significant factors affecting bus travel time reliability across the corridors. Among interviewed users, 67% are unaware of the bus schedule, 50% acknowledged the impact of dwell time on bus TTR. 88% of respondents agreed on the effect of bus frequency and reported long waiting times, with 53% waiting over 30 minutes to get the next bus & 85% believe dedicated bus lanes reduce travel time. Users rated the day of the week and time of day as significant factors in TTR, with average scores of 1.58 and 2.1 out of 5, respectively, indicates the unreliability of travel time over the study corridors that supports the findings of the other numerical analysis. Therefore, the study recommends the need for tailored strategies, including optimizing bus schedules, implementing dedicated bus lanes, and improving communication and frequency, to enhance bus travel time reliability and user satisfaction. These insights offer valuable guidance for policymakers and transport authorities aiming to improve bus public transport services in Addis Ababa.
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Keywords
Travel Time Reliability, Bus transport, urban corridors, regression model