Case Study: Lucan Roundabouts

This case study shows how upgraded roundabout designs significantly improve conditions for pedestrians and cyclists while preserving convenience for vehicles. These roundabouts are directly from the NTA National Cycle Manual and were funded by the NTA as part of the Sustainable Transport Measures Grant Programme. They were implemented by South Dublin County Council in 2014.11

Technical notes: The roundabout is intended to preserve the convenience of a roundabout for vehicles, but re-balance that convenience to provide for those walking, cycling and using the bus. The design is particularly attractive to more cautious drivers, due to its simple, legible design: there is only one lane entering the roundabout, one lane circulating the roundabout, and one lane to exit. While the roundabout design is quite new for Ireland, the design principles are well-established in European countries with superior road safety statistics.


  1. Castle Road Roundabout: 2.5 times as many kids walking  (183 to 458) Over twice as many cycling (8 to 20)
  2. Griffeen Road Roundabout: Over 5 times as many kids walking (60 to 314) Over 3 times as many cyclists in am peak hour (8 to 28)
  3. Although the council met with initial concerns from Dublin Bus, Councillors and residents concerned that it would impact on car traffic, and a local school who had contract with a private 3-axle bus.  Residents are now happy with scheme, and there is a plan for shared cycle track between roundabouts.
  4. Little or no change to overall AADT values at both roundabouts but a significant increase in the PM peak hour traffic volumes of between 14% and 17% – reason unknown but could relate to an increase in commuter volumes. AM peak hour traffic volumes at the Castle Road Roundabout have decreased by 125 veh which is a 10% reduction on 2012 counts which may be related to more pedestrian and cycle activity at the same roundabout.