Indian government-owned company Ircon International (IRCON is an acronym of Indian Railway Construction Limited) achieve the breakthrough of Tunnel 14 for Sivok-Rangpo Railway Project.

Construction 1952 metre long horse shoe type railway tunnel T-14 on Sevok (West Bengal) to Rangpo (Sikkim) is undertaken by Indian company Abir Infrastructure. According to Abir Infrastructure internet site, the "contract value is INR 123.51 Crores (US$ 19.02 Millions)   (1 US$=INR 65).  The execution has commenced in March 2017 with the scheduled completion of August 2019."

I think the foreign company Amberg is also involved in the project.

http://www.abir.in/projectscope.php?pid=25&mid=2&sid=39