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2
Initial Assessment of Options
A number of initial routes were developed based on
site visits and information recorded in the Constraints Study. Routes
in specific corridors were discarded early in the development stage
as described in the following paragraphs.
2.1
N78 Corridor (Kilkenny - Castlecomer - Athy)
A route corridor was investigated from north of Kilkenny City to
Athy following the N78 corridor and is shown in RSR2 Figure 6.1.
This corridor, when compared with other possible route corridors
which followed the River Barrow valley further east, was discarded
for a number of reasons.
Firstly, the engineering design was difficult and would require
extensive embankments and cuttings hence increasing the cost of
construction and maintenance. The route corridor passes over the
Castlecomer Plateau which has steep slopes at its edges. The steep
ground would require the road vertical alignment to have gradients
greater than 3% in order to keep cutting and embankment heights
within reasonable limits. This would have an impact on road safety
in that there is a progressive decrease in safety with steeper gradients.
Secondly, a considerable length of the route would be at a relatively
high elevation, with 15 kilometres at an elevation of over 150 metres
and 2 kilometres over 200 metres. This could lead to a reduction
in road safety and to maintenance problems due to the higher frequency
of fog, frost and snow at these elevations compared to a route at
a lower elevation. Winter maintenance requirements would be increased.
Thirdly, any route corridor following the N78 would not serve Carlow
directly. A new link road, or upgrading of the N80 or R430 would
be required, and may not attract the Carlow to Dublin traffic off
the existing N9.
In environmental terms the route corridor passes close to Castlecomer
and adjacent sites of ecological value, and does not appear to have
any over-riding benefits when compared to other route corridors.
In view of these reasons the route corridor was discarded prior
to Public Consultation No. 2.
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