The implementation of a 2+1 road scheme in Ireland: a case for Australia

This paper describes the implementation of the first greenfield ?2+1? road scheme in Ireland, which opened to traffic in late 2007 as part of the pilot program launched in 2002 to implement 2+1 roads throughout Ireland. A 2+1 road is a three lane road with a median barrier between the opposing directions. The direction of flow with two lanes alternates along the route to allow defined sections of overtaking. The median barrier prevents imprudent overtaking manoeuvres into oncoming traffic, which has significant proven safety benefits at lower costs than divided carriageway construction. The policy has evolved to ?2+2? type roads in Ireland, which provides additional capacity and safety benefits over single carriageway roads.

Ireland?s National Development Plan (Irelands 10 year infrastructure plan), proposed that 850 kilometres of the National Primary road network would be upgraded to a 2+1 road type if the pilot was successful, equating to approximately 30% of the National Primary road network. Ireland has a large rural road network, which accounts for a significant proportion of fatalities and serious injuries, with low traffic volumes that do not justify dual carriageway construction.