This investigation deals with the serviceability analysis and increased axle load performance of Bridge No. 541 of UNESCO recognised Kalka Shimla Mountain Railways, which is a multi-storey arch gallery stone masonry bridge situated in the state of Himachal Pradesh, India.  For this purpose, a finite element (FE) model was developed based on the drawings and reports available in Shimla Division, Northern Railways, India. Further, the results obtained from ambient vibration test (AVT) and operational modal analysis (OMA) is utilized to model update the initial FE model by modifying the mechanical properties of stone masonry. The serviceability against present-day axle loading (H Class Loading, Indian Railways) and present speed of the train is assessed.  At last, a parametric study is conducted to understand the feasibility to attain higher speeds (up to 40 kmph) of the present axle load and higher axle load with different speeds of the train over the bridge to check the serviceability conditions advised in the Indian Railways code and also International codes. Finally, the study concluded that Bridge No. 541 of Kalka Shimla Mountain Railways can sustain speeds up to 40 kmph for current axle loading satisfying serviceability conditions.