Be sure to allow extra time if your journey to Dublin Airport involves the
M50 ring road toll plaza which lies between the N4 and N3 interchanges.
The tolling operation is carried out by a private monopoly (NTR) and the
facilities they have installed are appallingly inadequate for the traffic
volumes on this highway system.
Traffic queues of several kilometres build up in the North and Southbound toll approaches at various times of the day. Long queues can also build up at off-peak times when some toll lanes are closed completely!