In conclusion, because of their high energy density, minimal maintenance needs, and affordability, lead-acid batteries are a great option for backup power in subway systems. They can be utilized for various applications such as emergency lighting, communication systems, signaling systems, ventilation systems, auxiliary power units, control systems, escalators, elevators, and ticketing systems. The reliable backup power provided by lead-acid batteries is essential for maintaining the safety and operation of subway systems, ensuring that commuters can travel efficiently and safely.