Investigating the Wheel Wear of Addis Ababa Light Rail Transit (AALRT)

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Addis Ababa University


This paper presents a reasonable approach to the causes behind the wheel wear at Addis Ababa Light Rail Transit (AALRT). Factors that led to wheel wear were investigated through site inspections/interviews with experts which gave the general truth of the problem and hinted potential factors that brought about the problem. Based on these findings, combination of issues related to inadequate friction management and poor track infrastructure are key factors which have led to wheel wear. Additionally, analysis of actual wheel data measurements taken from AALRT depots was used to find out the type of wear and from the two lines, North-South and East-West lines, identifying the line that is affected more by comparing vehicles from both lines. The tight curves at AALRT, mainly in the North-South line, contribute to high flange wear as of the wheel data analysis under taken. Then Multi-Body Simulation analysis of AALRT vehicle was carried out using SIMPACK software. AALRT vehicle’s performance was simulated in curves and straight tracks, then validated against the standards of the vehicle such as, coefficient of derailment, ride index and lateral force. Then parameters, namely critical speed, coefficient of friction and passenger loading, are identified from literature reviews and their effects on wear index were determined based on existing track infrastructure of AALRT. The simulation results gave longitudinal/lateral creepages and longitudinal/ lateral creep forces which were then used to calculate wear index. Based on the simulation results, critical speed of 40 km/hr led to the highest wear index of 1303.78 while the lowest wear index of 1240.14 is obtained at the critical speed of 20 km/hr, based on existing track infrastructure. In addition, higher coefficient of friction, 0.55 resulted in higher wear index of 3136.33; the lowest coefficient of friction, 0.25, resulted in the lowest wear index of 888.44. It is also evident that based on existing track infrastructure, overload of 20 tons caused higher wear index of 1278.63 compared to empty load obtaining the lowest wear index of 977.07. To minimize the problem of wheel wear at AALRT, suitable lubrication and better method of application, improved wheel/rail material, revised track alignment for easing of sharper curves and improved workshop facilities are recommended in this work.



Wheel wear, Addis Ababa Light Rail Transit (AALRT), Multi-Body Simulation, Wear index