The National Transport Agency has backed the decision to delay the DART Underground - saying the reasons for building it have changed in the meantime.

The Dáil's transport committee has been told that the original plans for the line no longer apply, because of other improvements made since it was first announced.

The project was shelved by the government due to financial pressure in 2011 and it was announced earlier this summer that the line would now need to be redesigned.

Hugh Creegan of the National Transport Authority says some of the original benefits planned for DART Underground are coming already: