4 Initial Review of Study
Area
A preliminary
study was carried out by collecting information on major constraints
within the full extent of the initial study area. This information
was methodically reviewed and displayed graphically such that
areas where the probability of finding a feasible route would
be unlikely (low routing potential) were 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 became 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 about 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, while
a route parallel to the N78 and along the Kilcullen link along
is only 28.4 km in length. In addition The Curragh is a proposed
National Heritage Area.
- An area,
primarily in Co. Wicklow, east of Moone village 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.
This study area
has been identified as a significant landscape feature in
the study area. There is a steep escarpment on the east side
generally 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 the difficulty of meeting geometric design standards and
hence capital cost for avoiding this area. The N78 corridor
to Castlecomer and Kilkenny remains in the constraints study
area, for further consideration.
Whilst environmental
and 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.
The areas in
the southern section excluded from further study are:
- Area on
east side of 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.
- A connection
to the Waterford Bypass at a location other than the proposed
N9/Bypass junction location/Granny should be allowed for
at this stage. This would be particularly relevant if the
Arrigle Valley offered a viable route.
- 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.
- It is recognised
that some areas of low routing potential, where they are
linear in nature will need to be retained if we are to meet
the study objectives.
A small additional
section to the study area was also included to the west of
Mullinavat. This is to give further flexibility to any route
options that may be developed to the west of the railway and
the River Blackwater.
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