IARNROD Eireann is to pay consultants €50,000 to come up with ways to tell the public that the capital will have two DART lines, even though they will not open until at least 2018.
The state rail company has sought experts to examine how to "effectively communicate the revised route characteristics", which will come about if the DART underground project goes ahead.
Iarnrod Eireann plans a 9km underground rail line from the Docklands to Inchicore, with stops at Docklands, Pearse Street, St Stephen's Green, Christchurch and Heuston Station.
The link, if approved by the Government, will result in two DART lines: one running from Hazelhatch/Celbridge to Howth, and the second from Maynooth to Greystones.
It will also increase capacity from 33 million passengers a year to 100 million, and will result in the DART linking up with Luas, Metro North and intercity services.
But planning permission has yet to be sought for the project, which, if approved, will not become operational until 2018. This is because the planning process could take up to a year, and a short-list of companies qualified to build the line has not been finalised.
There is also uncertainty as to whether the private sector would be able to secure finance for the project, expected to cost up to €4bn.
A spokesman for the project last night said the tender was not a full rebranding of the DART, but a call for companies to advise on how the changes could best be communicated.
He could not confirm the cost of the tender, but it is understood to be around €50,000.
"It's not a full rebranding of DART. It's specifically looking at what will happen when DART underground is in service, when there's two DART lines," he said.
"It's looking at how best to communicate that, how to differentiate between the two lines so people know where they're going.
"At Pearse Station, the DART lines will interchange. There'll be one overground, and one underground. The whole tender is for someone to figure out how best to communicate this to passengers."
The successful team will be required to analyse signage across the network and to recommend options for station identity, network logos and maps.
It is understood that a Railway Order Application, or planning permission, will be submitted at the end of June.