Minister for Transport Darragh O’Brien recently commented that the €12 billion-€20 billion MetroLink project was on track to proceed with excavation of certain sites starting some time in 2027. But he added that it was now possible that the underground railway would be built and opened on a “phased basis”.

He suggested the system could be made operational and opened for passengers at first from Swords to an unspecified point in the “city centre”. The southern leg towards a terminus at Charlemont in Ranelagh would be completed later. But he didn’t name a particular place where phase one would end in the city centre. Would it be at the Mater hospital or a planned station at O’Connell Street, near the north city Luas lines? Would the later second phase involve just three stations at Tara Street, St Stephen’s Green South and the Grand Canal near Charlemont Luas station? We don’t know.

Other questions remain unanswered, including the total cost of phase one, the additional cost of the remainder of phase two, the time frame for building phase two and whether the opening would be in 2035.

Would it be just a matter of boring the complete tunnel planned but leaving the southern leg for later completion, with three stations built at a later date? What are the economic implications of a two-phase........

© The Irish Times