SIX different options are being considered for a high capacity transport system for north Dublin, including a reworked Metro North and a proposed extension of the Luas line to the airport.
Transport Minister Paschal Donohoe has said a number of different financing options, including private funding, will be considered when the Government decides next year which scheme gets approval.
Mr Donohoe said high capacity systems were needed to cater for Fingal and north Dublin's growing population, along with traffic to Dublin Airport.
The six options were whittled down from 25 public transport schemes which were identified and assessed and include:
l A new, cheaper, version of Metro North to Swords, coming in at between $1.43bn and 2.86bn.
l A Bus Rapid Transit Network that would cost up to €330m including 32.7km of dedicated roads.
l A Dart link from Clongriffin, under the airport and to Swords that could cost €790m.
l A spur on the Maynooth rail line from Drumcondra to Swords costing as much as €2.13bn
l A €1bn Luas extension from Cabra via the airport.
l And a combination of a Dart link and Luas extension at up to €1.3bn.
"The challenges we face in addressing congestion are both logistical and economic," Mr Donohoe said.
"By 2023, there will be an additional 40,000 journeys into Dublin each day. If they were all by private car, we would need to build 40 new multi-storey car parks in Dublin. That will not happen.
"The appropriate policies must be implemented to safeguard our future and public transport is vital. If we cannot move people around we risk choking the economy and not realising our economic potential," he added.
Fingal is one of the fastest-growing areas of the country, and has experienced consistent growth since 2002.
However, public transport systems have not kept up with the rapid rate of expansion, resulting in growing gridlock.
Mr Donohoe said "mistakes" had been made in the past, particularly around overly-optimistic projections on economic activity and growing populations.
Any project would be "appropriate", he said, noting that various sources of funding would be explored.
Meanwhile, a decision is to be made on the DART underground project next summer.