A group has announced proposals for a new six-line metro system to be in place by 2025.
The CEO of Metro Dublin, Jed van der Poll says the lines could be at a fraction of the cost of current plans - and save the commuter almost three weeks a year in travel time.
The lines would run from Ashbourne, Swords, Donaghmede, Rathfarnham, Blanchardstown and Adamstown.
These radial lines would then link up in a central loop to run under the city.
This would see 19 major hubs all link up with DART, Luas, mainline rail and bus routes.
The plan is based on the Metro system in Madrid - where architect Professor Manuel Melis Maynar built 120 kilometres of metro in just seven years.
Mr van der Poll says: "Because it's a third of the cost, the capital sum is so much lower and that can be funded by private investment.
"We would be looking for half of that funding - so approximately 4.5 billion - from the European Investment Bank (EIB).
The proposed Metro Dublin line (in red) | Image: metrodublin.ie
"That has extremely low interest rates, and it's why the EIB was set up - just for this type of infrastructure project in Europe".
They've also met with Transport Minister Shane Ross.
"He was a very positive response. I was warned that Shane Ross is a very srtaight-forward man and if he thinks it's a non-runner he'll tell you stright to his face.
"He gave us 45 minutes if his time, we were very pleased", Mr van der Poll says.
The minister is examining the information.