4
Initial Review of Study Area
Given the size of the Initial Study Area for the scheme (see
Figure 1), a preliminary study was undertaken to determine
whether the study area could be refined. This was carried
out by collecting preliminary information on major constraints
within the study area. This information was methodically reviewed
and displayed graphically such that areas where the probability
of finding a feasible route would be unlikely (i.e. low routing
potential) could be identified. The issues that were considered
included:
-
engineering constraints
- the
existing infrastructure, land use, topography and physical
features
- planning,
development and socio-economic character
- identification
of sites or areas of environmental significance or sensitivity.
These
areas of low routing potential, and adjacent areas which become
areas of low routing potential by association, have not been
considered further at this stage of the project. Such areas,
while not completely eliminated from the study, will only
be reconsidered should routing subsequently prove not to be
feasible within the remainder of the study area. The results
of this exercise are shown in Figure 2, which defines the
Constraints Study Area and comprises an overall reduction
of 500 sq.km. from the initial study area.
The
areas in the northern section excluded from further study
are (listed north to south):
-
An area south of Kildare town including The Curragh,
east of the Dublin - Waterford railway line and north of
the N78.
Exclusion of this area still permits consideration of
a route north of Athy to join the proposed Heath - Mayfield
Motorway at a new interchange and routes parallel to the
N78 to join the M9 at Kilcullen. However an intermediate
northern route joining the proposed M7 east of the railway
has little or no cost advantages over a route to Kilcullen
and would be less efficient in that traffic to and from
Dublin would need to travel considerably further (via
the proposed M7) compared with using the M9 Kilcullen
link. For example, the journey length from Athy via the
northern route west of the railway to the M7/M9 merge
is 38.9 km, via a route parallel to the N78 and the Kilcullen
link this distance is only 28.4 km. In addition The Curragh
is a proposed National Heritage Area.
-
An area, primarily in Co. Wicklow, east of Moone which
contains Grange Con and ground rising to over 200m culminating
in the summits of Corballis Hill, Hughstown, Tinoranhill
and Brewel Hill.
The
area has landscape significance with views towards Castledermot.
The height of the ground and steep escarpment to the south
are engineering constraints. Any route would require extensive
earthworks for embankments and cuttings. This would significantly
increase the cost compared to a lowland route and would
also be more visually intrusive in the landscape.
-
The Castlecomer Plateau
This
area has been identified as a significant landscape feature
in the study area. There is a steep escarpment on the
east side rising to over 250m and over 300m in some areas.
The area of high ground is considerably reduced to the
north-west, where the N78 crosses a col near Farnans at
a height of 230m. Significant parts of the plateau have
been identified as of high amenity and are designated
as Areas of Special Development Control in the Kilkenny
and Laois County Development Plans. In addition there
are strong engineering reasons on grounds of cost for
avoiding this area. The N78 corridor to Castlecomer and
Kilkenny remains in the constraints study area, for further
consideration. However, the combination of additional
cost to traverses the high ground and the remoteness of
corridor from the major population centre of Carlow Town
may make any route in this corridor unattractive.
Whilst
engineering complexity and hence capital cost, has been
used as a reason for excluding the areas described above,
should 'lowland' routes become very expensive or infeasible
for any reason then these areas could be revisited.
As with the northern section, the southern section of
the study area was analysed using the methodology explained
at the beginning of this section. Figure 2 shows the areas
excluded from further study, which are: -
-
Area on the east side of the initial study area close
to the Rivers Nore, Barrow and Arrigle
- An
area of high ground on the west side of the Arrigle Valley,
forming part of the South Kilkenny Hills
These
areas have been omitted as a result of a combination of
major constraints identified and meeting the objectives
of the scheme. The following additional factors were considered
when refining the southern study area;
-
A corridor to the east of Thomastown should be retained,
given the difficult constraints associated with that area.
-
It is not recommend to reduce the study area to take account
of relatively small pockets of areas, which are considered
to have low routing probability. Instead combinations
of small areas are looked at, where it is possible to
provide a meaningful reduction in the study area, without
affecting the opportunity to identify feasible options
for route selection.
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