A proposed new MetroLink rail service has been compared to imposing a 'Berlin Wall' on south Dublin as it will segregate communities, an Oireachtas committee has heard. 

Residents who are members of the Rethink MetroLink South City group came before the Oireachtas Transport Committee to explain their objections to the proposed new Metro line. 

Peter Nash outlined the concerns of residents in the Ranelagh-Rathmines area about the planned transformation of the current Luas line to a high-speed over-ground line.

He said that while "a tram system is relatively benign in terms of community impact, the impact of a high-speed rail system is totally different. Because of its speed, frequency and inaccessibility, segregated high-speed over-ground rail, in effect, creates a clear physical partition within communities."

It will divide communities, create difficulties for families with young children and limited mobility and create congestion through displaced traffic, the group claimed. 

Mr Nash was critical of a proposal from the National Transport Authority (NTA) and Transport Infrastructure Ireland (TII) to have a stepped overpass at Dunville Avenue. He said: "Sadly their latest partial proposal focuses exclusively on only one of the many issues we have highlighted, namely the Dunville Avenue crossing." 

He added, "The emerging MetroLink proposal has been compared to the imposition of a Berlin Wall in the south city. The latest proposal from MetroLink is akin to the opening of a 'Checkpoint Charlie' on that Berlin Wall. However, even with the opening of Checkpoint Charlie, the wall remained intact and the community remained divided."

Local Labour party Senator Kevin Humphreys said proposals to have driverless trains on the new route is fuelling the 'Berlin Wall' fears.

He said: "If there is nobody in the front of the train to see if there is somebody on the track, they have to build a very large infrastructure on each side of the track to prevent people getting on". 

Mr Nash also warned that the construction phase of MetroLink will have have a significant impact on existing Luas Green line users given that it is proposed to shut down that line for at least nine months during construction.

The Rethink MetroLink South City group has questioned the value of concentrating such a large amount of capital investment in a relatively small area.

He added that "serious questions arise about the waste of public money in dismantling the existing Luas line which has only recently been expensively constructed." 

Local TDs Kate O'Connell, Eamon Ryan and Jim O'Callaghan were among those to highlight the concerns of people in Dublin Bay South at today's meeting. 

Fine Gael TD Kate O'Connell said the Transport Committee has been told that the closure of the Green line would take six months but she added: "I don't see how that would possibly be the time frame."

Kevin Humphreys questioned the financial impact where the Green line will closed for "a minimum of nine months." He said this will put 75,000 commuters back on the roads  and cut off public transport to businesses in places like Sandyford and the Beacon area.

Fianna Fáil TD Jim O'Callaghan pointed out that there is a socio-economic divide developing along east-west lines and part of their reason for that is that the eastern side has been better served by public transport routes.

A number of TDs, including Fianna Fáil TD John Lahart, suggested an alternative route to the proposal saying MetroLink should be developed to serve areas such as Terenure, Rathfarnham and Firhouse, as the planned route is already well served by the existing Luas green line. 

Jennifer Gilmore, of the Rethink MetroLink South City group, said she has witnessed how the Green Luas line has "enhanced and revitalised our community." But her group is strongly opposed to the proposed new overground train.