The Oudh and Tirhut Railway was formed on 1 January 1943 by the merger of the Bengal and North Western Railway, the Tirhut Railway (BNW operated), the Mashrak-Thawe Extension Railway (BNW operated), the Rohilkund and Kumaon Railway and the Lucknow-Bareilly Railway (R&K operated). The Oudh and Tirhut Railway was later renamed the Oudh Tirhut Railway; it merged with the Assam Railway and the Kanpur-Achnera section of the Bombay, Baroda and Central India Railway to form North Eastern Railway (headquartered in Gorakhpur, with a divisional headquarters in Izzatnagar), one of the 16 zones of the Indian Railways.