The $NZ 4.4 billion project under construction in Auckland involves creating a 3 kilometers long double-track rail tunnel underneath Britomart Transport Centre and Mount Eden Railway Station; the building of two new stations, at Aotea Square and Karangahape Road; and conversion of Britomart's existing terminus station into a through-station to Mount Eden Station, which will serve as an interchange between the new CRL line and the existing Western Line.