The tunnel is situated near New Haflong station building and passes below Haflong town and the underground excavation work from both ends met each other on Sunday in Dima Hasao district, said NF Railway senior public relations officer (construction) Md M M Y Alam.
The 3,235 meter long tunnel connects the newly built New Haflong railway station with Jatingalumpur railway station, he said adding it is considered as one of the most critical tunnel in the 210-km broad gauge track.
It was scooped out with great difficulty due to soil conditions of the area and geological issues. Adverse geological conditions were encountered during underground excavation of the tunnel and its completion has been seen as a major challenge for the construction engineers of NF Railway, he told reporters Monday.
A high level team of the Construction Organisation comprising its Chief Executive Administrative Officer Ajit Pandit, Chief Engineer R K Ginger and others inspected the tunnel yesterday.
Terming it as a feat of the Railways in 2014-15, Alam said Construction Organisation has in a major breakthrough made the much awaited and difficult tunnel gauge conversion project.
Though work on the tunnel had begun in September 2005, it did not progress well initially due to several geological problems.
However, from 2012 onwards the work resumed and now the tunnel has been opened, Alam said adding, the remaining work of benching, lining and invert is scheduled to be completed by January next year.