Using onboard Energy storage system for Addis Ababa Light Rail Transit is the main objectivernof the thesis. In this thesis for analysis of the efficiency of using onboard energy storage systemrnin AALRT, North to South line is used for modeling and simulation. Mathematical modeling ofrnthe traction force, Power, and energy consumption has been developed and energy consumptionrnand regenerative energy have calculated for the lines from station to stations in the line. Forrnround trip of Menelik II square station to Kality station the generated brake regenerative energyrnis 30.01 kWh. This energy is 12.4% of the total energy consumption of the traction for the roundrntrip of Menelik II square to Kality stations.rnHybrid energy storage system is selected for onboard energy storage system. The HESS designrnhas been formulated, with energy capacity of 79.78 kWh and mass 2460Kg. HESS/HybridrnEnergy Storage System is used for improving efficiency of energy and power. Super-capacitor isrnused for power efficiency and efficient brake regenerative recapturing, and Li-ion battery forrnenergy saving efficiency.rnFrom the simulation of onboard energy storage system, the hybrid of Super-capacitor and Li-ionrnbattery with capacity of 79.78kWh is used as per the design. To supply traction energy ofrn11.28kWh the state of charge of the battery is discharged up to 99.9%, whereas the SoC of thernSC is discharged to 94% and recharged to 99% by the brake regenerative energy. In thernsimulation the ESS supply power during acceleration up to 640kW.rnBased on the research result, it is concluded onboard energy storage system is an effectivernsolution for recapturing the brake regenerated energy. The regenerated energy is 12.4% of therntraction consumption energy which is used to increase the energy efficiency. By using thernregenerated energy saved in ESS to supply energy for traction during power shortage and alsornfor accelerating and up gradient traction. The ESS supply energy for the traction during gridrnelectric energy supply outage and to minimize energy consumption of the traction.