Engineering, Passenger Rail

Works progresses for Auckland CRL

Preparation work for Auckland’s City Rail Link (CRL) project has made great strides recently, with the trench in which the tunnels are to be built now reaching nine metres underground.

Due for completion in 2023, the $3.4 billion CRL will extend the existing rail line underground through twin tunnels from Britomart station to significantly redeveloped Mount Eden station via two new underground stations – Aotea Station and Karangahape Station.

The formation of the walls (built to retain the soil and stop water from entering the site) – on Albert Street and under the Commerical Bay development, are beginning to indicate the path the tunnels will take.

The works for CRL are occurring at the latter location concurrently with the digging of the foundations for Precinct Properties’ new 39 level commercial office tower and a retail centre.

The trench under Albert Street is currently 9 metres deep (almost half-way to the required depth of 18 metres), dug using long-reach excavators above ground and smaller machinery inside the reinforced trench.

After the construction of the trench is complete, the concrete floor, walls and roof will be cast and the completed structures backfilled.

The sloped gradient of the landscape along the CRL route means that the depth of the tunnels will vary along their length. At the ends of the of the tunnels, at Albert Street and Mt Eden, construction will occur at a relatively shallow level, allowing the “cut and cover” method where the tunnel is constructed from the surface.

Work at the Customs Street intersection is also soon to finish, completing a bridge deck that will allow excavation at this location.