2.5 Upgrading the N9 to Dual Carriageway / Motorway
Standard
Early in the project the advantages and disadvantages of routing
the proposed N9/N10 high quality dual carriageway / motorway along
the existing N9 were considered. However the brief for the scheme
stipulates that the new road shall be a high quality dual carriageway
or motorway based on the strategy outlined in the National Development
Plan 2000-2006.
An initial review was carried out to determine sections of the existing
N9 which were within the settlement areas and would require an off-line
bypass. There were proposals for bypasses at Carlow, Castledermot,
Thamestown and Lukeswell. Secondly there are lengths of the N9 where
the horizontal alignment is below standard of a high quality dual
carriageway / motorway. For these sections there is no alternative
but to go "off-line" to achieve the necessary standard.
Examples of this arrangement are shown in RSR2 Figure 6.6 and RSR3
Figures 6.6, 6.7 and 6.8. These factors reduced the length of possible
on-line improvement from 107km to 50km (47% of total length). Over
53% of the route would need to be "off-line" to avoid
settlements and to improve the horizontal alignment.
A sample length of on-line route was studied in more detail and
a number of major disadvantages were identified: (i) Service roads would be needed over significant lengths
of the on-line section to maintain access to properties and land.
This would increase the cross-section, verge to verge, compared
to an off-line solution, from 26 metres to 49 metres. (ii) A significant number of properties close to the existing
N9 would have to be demolished to accommodate this very wide cross-section. (iii) Access for communities located in the vicinity of the
N9 would be severely affected by restricting access to the new road.
Local journeys and journeys to and from the new road would be forced
to use low standard rural roads. (iv) Severance would be significant for properties and land
currently fronting the N9. (v) Extensive traffic management measures would be required
during construction which would increase the number of accidents
and increase construction costs. (vi) There would be significant delays to traffic on the
existing N9 during construction.
For
the above reasons the "on-line" option was discarded
