TII and Fingal County Council
JV Partner


As part of the overall upgrade of the M1 motorway, Roughan & O’Donovan-AECOM undertook a redesign of the Lissenhall interchange, one of the most significant links on the national road network.


Our scheme design involved the introduction of slip roads through the roundabouts at the signalised dumbbell interchange.

A grade separated route, which included the construction of 4 underpasses and several retaining walls, was devised for cyclists and pedestrians.

Separate at grade provision was also included.


  • Unique right turn Hook Lane through a roundabout
  • Amending the southern roundabout to a ‘hamburger’ arrangement
  • Design of high quality pedestrian and cycle facilities at a motorway interchange


The key issue challenge was queuing on the R132 and R126 south bound in the morning peak and R132 north bound and across the bridge in the afternoon peak.


The upgrade reduced queuing levels and journey times on all approaches to the interchange, protecting the efficient operation of the M1 motorway.

Services provided:

  • Civil engineering design
  • Traffic engineering