Dublin Chamber says any delay to Metro North will cost the city jobs and investment.
The project aims to carry more than 30m passengers a year, with a trip from O’Connell Street to the airport taking just 19 minutes.
Work is due to begin on the light rail system in 2021 and be finished six years later.
CEO of Dublin Chamber Mary Rose Burke described it as an "important signal" to the people of Dublin.
"The political decision has been made to progress with Metro North and any rollback on that is damaging to credibility," she said.
"This is a hugely important signal to businesses, people of Dublin, people looking to invest or move to Dublin, that when we say we will build something - we will build it," she added.
Edgar Morgenroth, Associate Research Professor with the ESRI argues that the project will not solve Dublin's congestion problems.
"The Metro North project will deal with transport in one relatively narrow corridor and it will absorb a very significant amount of money that could not then be otherwise used for projects in the rest of the city," he said.
"It will not really deal with the full transport issues in Dublin," he added.