This work presents a powertrain architecture and control system design of a hybrid electric tower car (HETC), which is powered by overhead electric (OHE) line and battery energy storage systems (BESS). The main goal is to provide an alternative solution to diesel electric tower cars (DETC) used by Indian Railways and reduce CO2 emissions. The proposed HETC operates on BESS alone, allowing essential services like maintaining overhead equipment and tracks. Also, the system facilitates regenerative braking, a feature not available in existing DETCs; this redirects recovered energy towards the battery or OHE line, thereby augmenting the overall energy efficiency. A control algorithm has been developed to utilize OHE and BESS for powering tower car in all possible operating conditions with operational flexibility and smooth transition between all operating modes. The performance of the proposed control strategy is validated using simulation studies done using MATLAB Simulink model.