Minister for Transport Paschal Donohoe is due to make a decision by the summer on a choice of six options to link Swords and the airport with Dublin city centre.
They include a revised Metro North, two different DART links, a Luas link, a Bus Rapid Transit system or a combination of DART and Luas.
The public consultation closed this evening and it comes as transport groups such as the Automobile Association warn that traffic congestion is returning to levels not seen since the Celtic Tiger years.
The National Roads Authority has reported that toll numbers on the M50 have increased by nearly 30% since its upgrade.
The NRA predicts that car ownership will increase nationally by 24% between 2011 and 2035.
It expects there will 40,000 extra journeys into Dublin by 2023.
If all of these were by car the city would need 40 more multi-storey car parks.
