Muzaffarpur–Gorakhpur line (via Hajipur, Raxaul and Sitamarhi)

The Muzaffarpur–Gorakhpur line (via Hajipur, Raxaul and Sitamarhi) is a set of three lines connecting Muzaffarpur in the Indian state of Bihar with Gorakhpur in Uttar Pradesh. The lines run in an east–west direction between the Gandak and India–Nepal border, covering North Bihar west of the Kosi river and eastern Uttar Pradesh. The southernmost of the three lines connects via Hajipur Junction, Sonpur Junction and Chhapra. The central line connects via Motihari (also to Raxaul) and Sugauli. The northern line connects via Sitamarhi (newly constructed single diesel BG) and Raxaul. The lines have interconnections between them and the northern line has extensions to places near the India–Nepal border.

History
Railway lines in the area were pioneered by Tirhut Railway and the Bengal and North Western Railway lines in the 19th century. In his book The Indian Empire, Its People, History and Products (first published in 1886) W.W.Hunter, says "The Tirhut State Railway with its various branches intersects Northern Behar and is intended to extend to the Nepal frontier  on one side and to Assam on the other."

The area was developed with metre-gauge tracks. The 229 km Samastipur–Narkatiaganj loop was developed in stages between 1875 and 1907. The Samastipur–Darbhanga line was opened for famine relief in 1874 and opened to the public on 1 November 1875. The 72 km-long Nirmali branch (Darbhanga–Nirmali) between 1883 and 1886. The Barauni–Bachhwara line was opened in 1883. The Bachhwara–Bagaha line was developed in stages between 1883 and 1907. The Sakri–Jainagar branch was opened in 1905. The 51 km-long Hajipur–Muzaffarpur line was opened in 1884. The 270 km-long Tirhut main line from Katihar to Sonpur was developed in stages between 1887 and 1901. The 105 km-long Chhapra–Thawe line was opened in 1910. The 320 km-long Chhapra–Allahabad line was developed between 1891 and 1913. The Maharajganj branch line was opened in 1907. The Siwan–Kaptanganj line was opened between 1907 and 1913. The 127 km-long Bhatni–Varanasi Chord was opened between 1896 and 1899. The Jhanjharpur–Laukaha Bazar line was opened in 1976.

The lines were converted to broad gauge in phases starting from early 1980s. Samastipur to Darbhanga (metre to broad gauge) was converted around 1983. Siwan to Thawe (metre to broad gauge) was converted in early 2006. Gauge conversion of the 268 km-long Jainagar–Darbhanga–Narkatiaganj line that was started in 2011 was completed to Raxaul in February 2014 and to Narkatiaganj in 2017. The Sakri–Laukaha Bazar–Nirmali conversion is under process.

Electrification
The electrification work was completed for the entire section in December 2014.

Sections

 * Barauni–Samastipur section
 * Samastipur–Muzaffarpur section
 * Muzaffarpur–Hajipur section
 * Muzaffarpur–Gorakhpur main line

The 59 km long existing Chhapra–Hajipur line was being doubled.