Assessing & Quantifing the Level of Traffic Congestion at Major Intersections in Addis Ababa (A Case for East-West Corridor)
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Date
2011-09
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Addis Ababa University
Abstract
Traffic Congestion is an ever growing chronic problem in the transportation system soon after
the invention and mass production of automobiles. All major cities both in developed and
developing countries are facing the problem due to increasing travel demand which follows
economic and population growth. Traffic congestion directly affects commuters with an
increased travel time, excessive delay in a queue, increased fuel cost, delay for important
appointment and job, loss in productive hours; and it indirectly affects the living standard and
the environment as well. Hence, traffic congestion cause upon road users and cities to incur a
significant amount of money for both economic and social costs. Quantifying the level of the
traffic congestion and understanding how much effect and cost are being incurred due to traffic
congestion; hence, will be important for making improvement decisions and evaluate
implemented mitigation measures.
Following the economic and population growth in Addis Ababa, traffic congestion problem has
emerged and the problem is even growing faster. In this study, the level of the traffic congestion
in Addis Ababa city was quantified using travel time approach. The city’s one of the most
congested East-West corridor was considered and travel time, traffic volume, and vehicle
occupancy data were collected at four midblock and four intersections. Accordingly, the travel
rate, the delay rate, total travel delay (Veh-Min and Per-min), buffer index and planning time
index were calculated. And also, the average hourly travel rate is correlated with the average
hourly traffic accident data and congestion spots and accident black spots were plotted on the
GIS map to see the relationship between the traffic accident and traffic congestion.
Accordingly, the result showed that on average about 18,000 Veh-min or 38 Veh-day and about
169,000 Per-min or 352-person-day are wasted at each major intersection entry and the city
incurs annually about 5-8 Million Birr per intersection only for vehicle and fuel cost. The result
also showed that the city’s traffic accident rate correlated with travel rate better than traffic
volume and the congestion spots identified from questionnaire data conside with the black spots
identified by the national road safety agency.
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Road and Transport Engineering