D18 Kronstadtunnelen og inntrekkstunnelen

• Client: Bergen Light Rail
• Main contractor: Veidekke Entreprenør AS
• Contractor: Metrostav Norge AS
• Construction period: 11/2021 – 04/2022
• Price: 32 400 000 NOK w/o VAT

It is part of a new urban railway development in Bergen. Metrostav Norge performed excavation and securing of Kronstadtunnelen and a service tunnel.

Kronstadtunnelen tunnel was an existing 460 m long tunnel with a protected stone-walled portal. The work included widening the tunnel from a profile of 30 m² to 58 m² in length of 370 m, in an urban area near a hospital. The work was limited not only by noise and seismic requirements, but also by very limited places for construction. The work also included securing the tunnel with bolts. The newly operated tunnel will be used by pedestrians and cyclists.

Inntrekkstunnelen is a new parking tunnel for the light rail, with a length of 89 m. Tunnel with profile 85 m² was excavated in quartzite in urban areas. Part of the work was injection and securing of the tunnel with bolts.

• Minimal space for construction site, impossible to build a workshop tent, minimal space for storage of materials
• Strict noise and vibrations limits – Excavation near the hospital, large time limitations
  for performing blasting work and other noisy activities
• Kronstadtunnel – due to coordination of other works, excavated from both portals.
• Protection of a historical portal made of rocks
• Major restriction of blasting works
• Low overburden up to 30 m
• Use of electronic detonators