A $1.7-billion public transit line dubbed the “missing link” in Auckland, New Zealand’s rail and bus network is a step closer to construction. Two joint ventures are beginning a $2-million initial design phase for the City Rail Link (CRL), which will include 3.6 meters of tunnels.

Downer NZ, Soletanche Bachy JV, and Connectus, a joint venture of McConnell Dowell and Hawkins, will begin preliminary design for the north-south route that will cut through the heart of the city, joining the major hub of Britomart with Mount Eden. It will serve an anticipated 30,000 passengers at peak hours—double the current number—and improve intermodal connections throughout New Zealand’s most populous city, says CRL project director Chris Meale.