City Rail Link (CRL) is Auckland’s first underground rail line and the largest transport infrastructure project ever undertaken in New Zealand. CRL will transform the downtown Britomart Transport Centre into a two-way through-station, doubling the capacity, reducing travel times and supporting a growing population with a world-class transit system.
The 2.1 miles (3.45km) twin tunnel underground rail link will run up to 138ft (42m) below the city centre and includes the construction of two new inner-city underground stations (Karangahape and Aotea) and rebuilding the existing Mt. Eden Station. Construction of the stations and tunnels is through cut-and-cover and tunnel boring machine (TBM) methodologies, except for Karangahape Station (K-Road) which is being excavated by roadheaders due to its layout and dimensions.
The main construction contract for the stations and tunnels was awarded to The Link Alliance Joint Venture, comprised of Vinci Construction Grands Projects S.A.S, Downer NZ Ltd, Soletanche Bachy International NZ Limited, WSP Opus (NZ) Limited, AECOM New Zealand Limited, Tonkin+Taylor Limited and CRL Ltd.
The main construction contract for the stations and tunnels was awarded to The Link Alliance Joint Venture, comprised of Vinci Construction Grand Projects S.A.S, Downer NZ Ltd, Soletanche Bachy International NZ Ltd, WSP Opus (NZ) Ltd, AECOM New Zealand Ltd, Tonkin+Taylor Ltd and CRL Ltd.
Ventilation and dust control are needed to keep workers’ exposure to fumes and dust at safe, acceptable levels. Grydale provided ventilation design consultancy to develop an extract ventilation system for the excavation of K-Road Station.
A JMS-60-MES dust collector and a 50m³/s axial fan was suppied to provide ventilation and dust control.
K-Road will have two entrances, one at Mercury Lane and one in the center of Beresford Square. K-Road is the deepest of the CRL stations at 105ft (32m) below the surface.
The station is being excavated by two roadheaders because the Karangahape tunnel needs to be larger than the TBM to accommodate four underground station platforms which will be 492ft (150m) long, suitable for nine train cars to increase capacity from the current six. The platform tunnels are maximum 29ft (8.9m) high and 32ft (9.8m) wide with an area of 263ft² (80.2m²).