• Employer: National Railway Infrastructure Company
• Contractor: Infrastructurno Stroitelstvo – Geostroy Consortium
• Project completed in 2021

Infrastructurno Stroitelstvo – Geostroy Consortium completed the construction and assembly works under the project Rehabilitation of the Railway Track, Related Facilities, Catenary and Power Supply Systems on Koprivshtitsa - Stryama Railway Section from km 100+525 to km 106+337. The total length of the railway section is 5.8 km.

Almost the entire section runs through Koznitsa Tunnel which is 5.6 km long and is the longest railway tunnel in Bulgaria.

In addition to the complete rehabilitation of the tunnel, the contract scope includes design and full railway track renewal in the section.