During British rule, all links from the northern part of Bengal and Assam to the rest of India were through the eastern part of Bengal. The most important connection was the Calcutta–Parbatipur–Haldibari–Siliguri link first established in 1878 and then developed in stages. During the nineteenth century, Lalmonirhat was linked to the Dooars. In pre-independence days, a metre gauge line running via Radhikapur, Biral, Parbatipur, Tista, Gitaldaha and Golokganj connected Fakiragram in Assam with Katihar in Bihar. With the partition of India in 1947, all these links were lost. Indian Railways took up the Assam Link Project in 1948 to build a rail link between Fakiragram and Kishanganj. Fakiragram was connected to the Indian railway system in 1950 through the Indian portion of North Bengal with a metre gauge track. The New Jalpaiguri–New Bongaigaon section was partly new construction, partly old line converted to broad gauge in 1966. The long wide broad gauge Siliguri-Jogihopa line was constructed between 1963 and 1965.
Branch lines
The Haldibari–New Jalpaiguri linehas gone through two successive gauge changes. As most other railway tracks in the area were metre gauge, the line was converted from broad gauge to metre gauge in 1949. Then in 1960s when broad gauge was introduced in the area, the line was converted back to broad gauge and connected to the new station at New Jalpaiguri. The metre gauge branch line from Malbazar in Jalpaiguri district to Changrabandha in Cooch Behar district is now an isolated section, with no service, as per the railway time table. In pre-independence days, the line was up to Mogalhat, now in Bangladesh. The present metre gauge line on the Bangladesh side from Burimari to Lalmonirhat is still functional. The Alipuduar–Bamanhat branch line ends near the India-Bangladesh border across the Dharla River. In pre-independence days, it used to connect to Mogalhat, now in Bangladesh, across the Dharla. The bridge is broken. The line from Golokganj meets the branch line. The New Cooch Behar–Golokganj section is nearing conversion to broad gauge. The line passed through Gitaldaha at some point of time. The 66 km Fakiragram-Dhubri branch line was inaugurated after gauge conversionin September 2010.
Electrification
Electrification of the entire Katihar–Guwahati route is in progress
