Evaluating the Performance of Signalized Intersection and the Associated Economic Impact of Congestion: (A Case Study on Ras Mekonnen Street of Addis Ababa, Ethiopia)
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Date
2018-06
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Addis Ababa University
Abstract
Now days, traffic congestion is becoming a serious issue in developing countries in general and
in Addis Ababa in particular. Its major impact on the day-to-day activities of road users is not
limited to delay in travel time but also it affects the consumption of fuel and the surrounding
environment in terms of greenhouse gas emissions.
In Addis Ababa, the issue is becoming a great concern to its residents, transport managers and
planners. In light of the interest in testing the performance and optimization of Signalized
Intersection timing plan on major route corridor of Addis Ababa, this study was designed and
conducted on Ras Mekonnen Street between the Addis Ababa School of Commerce and
Estifanos, as it is the most signalized route corridor in the city and serves the city’s major traffic
population.
Based on Highway Capacity Manual (HCM), the current performances of signal operation on the
route corridor were assessed along with the cost of congestion results from Travel Time Lost,
Extra Fuel Consumption and Environmental Pollution costs. In addition, using Synchro 9
Simulation Software, the Intersection signal timing plan was optimized with respect to network
cycle length, offset and splits.
The result of performance evaluation indicated that all the Signalized Intersections under this
study serve the traffic demand with poor level of service (LOS F) resulting in costs to the
Country amounted to ETB:1,191,442.76 per hour due to extra fuel consumption and travel time
loss and also affected by pollutions with emission rate of 31,668.64 g/h of NOx; 206,796.22 g/h
of HC; 2,874,467.45 g/h of CO; 3,736,807.68 g/h of PM2.5 and 134,375,604.21 g/h of CO2
attributed by the on roads traffic on the study segment.
The simulation analysis for optimization shows that service quality at intersections can be
improved by changing the current operating cycle length of 188sec to 270sec for Estifanos
Intersection and 230sec for all other Intersections in the network, together with phase sequences
and splits. As a result, more than 550 vehicles will be relieved from stopping at intersections and
also extra 654 litters of fuel consumed by the vehicles per hour will also be saved owing to
improvement of signal timing.
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Keywords
Level of Service, HCM Manual, Synchro Software, Congestion, Optimization, Signalized Intersection