Need for the Scheme

There has been a long history of traffic accidents including fatalities at Slane which arise from the sub-standard alignment particularly in the vicinity of the Slane Bridge, the steep approach gradients in Slane Village and approaches to the Slane Bridge, and the high percentage of HCVs through the village.

In 2001 and 2002 ‘short-term’ measures were implemented comprising the segregation of HCVs from other vehicles on the southbound approach to the bridge and the introduction of traffic lights at the N2/N51 junction in Slane Village. Whilst these short-term measures have helped to reduce the number of incidents at Slane Bridge, they do not address the underlying safety issues associated with the sub-standard horizontal and vertical alignment, poor overtaking opportunities, junction with the N51 and high number of direct accesses. 


The existing problems on the N2 in the vicinity of Slane village, giving rise to the recommendation for a bypass, can be summarised as follows:

  • Traffic nuisance through Slane village (particularly with high numbers of HCVs).
  • Poor level of service on the section of the N2 road across Slane Bridge and through Slane village – all of this section is currently subject to a 30kph speed limit for safety reasons.
  • Residual safety issues relating to gradients in the village, at junction with N51, high HCV flow and sub-standard horizontal and vertical alignment at Slane Bridge.
  • Lack of overtaking opportunities.
  • High number of direct accesses.
  • Proximity of houses/properties to sub-standard N2 road.
  • Poor/deficient manoeuvrability for traffic at N2/N51 junction.
  • Limited facilities and reduced safety for vulnerable road users.


The objectives of this scheme will be framed and appraised in accordance with National Transport planning policy using the Common Appraisal Framework based on the following five criteria:

  • Economy
  • Safety
  • Environment
  • Accessibility and Social Inclusion
  • Integration


The provision of a bypass of Slane Village would aim to deliver the following improved functional and operational outcomes:
  • The bypass will be designed to TII’s Design Manual for Roads and Bridges (DMRB) standards to provide, as a minimum, an average inter-urban speed of at least 80km/h.
  • Reduction in frequency and severity of collisions.
  • Provide continuous or generous opportunities for overtaking.
  • Limit or remove all direct accesses other than at junctions with other roads. 
At the same time, maintaining a balance between the environmental, historical and archaeological aspects of this region so that its integrity, authenticity and significance are not adversely affected.