A war of words has erupted over a proposed ring road from the M50 through Ongar and Clonsilla, with accusations of “putting point-scoring before the bigger picture”.

A Sinn Fein motion passed at last week’s council meeting rejected the options proposed by Transport Infrastructure Ireland (TII) against the advice of officials.

Cllr Paul Donnelly (SF) said the 11 emergency diversion routes being considered by TII in the event of an incident on the M50 were unacceptable.

But Cllr Emer Currie (FG), who opposed the move along with party colleague Ted Leddy, said the motion was “incredibly short-sighted and damaging to the process of finding solutions to Dublin 15’s traffic problems”.

Cllr Donnelly warned: “If you built a road between Dublin 15 and the M50, it would become a sub of the M50 and people would use it to avoid the tolls every day.

“As it stands, the Liffey Valley is clogged up by people who are using it to avoid the M50.

“If you’re going to put in a link road, it has to be so far out that it doesn’t become accessible for people who are trying to avoid the tolls.”

TII says due to increasing traffic volumes on the M50, there is “a clear need to minimise the impacts of increased congestion … and to keep this vital national transport artery operating at all times”.

An Interagency Incident Coordination Group has put in place emergency diversion routes for the full length of the motorway, from its junction with the M1 to the M11, with the exception of junctions 6 to 7 between the N3 and the N4.

TII says “no viable existing route could be identified” and is therefore proposing a new ring road, with routes from Littlepace to Barnhill and Blanchardstown Road South to Lucan among the considered options.

Cllr Currie said: “Some routes are completely unacceptable, but others could finally put to bed the threat of a national road through St Catherine’s Park and remove congestion from Dublin 15.

“The communities of Laraghcon and Rokeby are choked with traffic as they are a rat run for the tolled M50.

“Ongar and Littlepace residents face lengthy commutes to get anywhere south of D15.

“What we have here is a chance to address these issues. But Sinn Fein, supported by Labour, Greens and Fianna Fail, have shot it down at the first opportunity.”