Wireless communication networks are recently taking an important role in railroad systems as railways now require high speed and high density operation with the aid of advanced information technology to improve maintenance efficiency and to handle passenger service growth. Train control systems are consequently changing from track circuitbased systems to communication-based systems. This paper analyses the role of wireless communication networks in recent railroad systems, reviews foreign cases, and then suggests a communication network constructing policy for increased transport capacity increase, securement of safety, and efficient train control.