5 Development of Preferred Route

5.2 Northern Assessment

Results of Assessments
A formalised process was applied to the evaluation process which is documented in Chapter 17 of Volume 2 and summarised in the Impact Matrices, RSR2 figures 17.1 to17.4 and the Selection Matrices shown in tables 17.1 to 17.8 of Volume 2. These steps are summarised below together with the results of each evaluation.

Step 1: The engineering and environmental effects of each route corridor within each Section A to D were recorded on an Impact Matrix. Also lengths of route where the route corridor could be modified to overcome major impacts were identified. Impact Matrices for Section A to D are shown in RSR2 figures 17.1 to 17.4.

The route options were compared under the following headings: -

• Impacts on People
  
• Flora, Fauna and Fisheries
  
• Archaeology and Cultural Heritage
  
• Agricultural Land Use
  
• Landscape and Visual
  
• Engineering
  
• Geology and Hydrogeology
  

Step 2: Where alternative routes started and finished at common points within a single Section, the two route corridors were compared using a summary Selection Matrix and the less favourable route corridor discarded.

As a result, Route A3 was discarded in view of its greater impact on people. Route A4 was discarded because of its ecological and landscape impacts near Calberstown and the impact on a major pig unit at Kilgowan.

Overall Route D3 was seen to have advantages compared with Route D5 particularly in relation to the crossing of the River Barrow. Hence Route D5 was discarded from further considerations.

Step 3: Matrices for the main Traffic/Cost-Benefit/Socio-Economic Impacts were prepared for a number of representative overall Route Options (Route 1, 2, 3, 4 and 7) see table 17.9 of Volume 2. Those route options which were deemed to be less favourable were discarded from further evaluation.

Consideration of the traffic issues indicated that routes to the east of Carlow were preferred. Excellent access to Carlow Town could be provided via junctions on the existing N9 to the north and south of the town. With routes to the west of Carlow, traffic volumes entering Carlow Town from the west increased significantly compared with the do-nothing situation. Traffic would have to cross the town to reach the industrial/commercial developments which are predominantly on the east side of the town.

The Present Value of Benefits was higher for the routes to the east of Carlow. As the capital costs of all routes were similar, these routes also showed higher Benefit to Cost Ratios.

In socio-economic terms the favoured route was via Athy and east of Carlow as it best served Athy and provided excellent access to Carlow Town. The issues summarised above, together with consideration of the engineering and environmental impact of Route C4 west of Carlow, led to the conclusion to discard route options to the west of Carlow Town. This decision reduced the number of possible route options significantly and, in the next step, the remaining route options were compared on a section by section basis.

Step 4: Selection matrices were drawn up for the remaining route corridors in each section. These are shown in tables 17.4 to 17.7 of Volume 2.

From Step 4, Route C6 at Carlow emerged clearly as the Preferred Route when compared with Routes C3 and C5. Route C6 directly affected significantly fewer properties and also had fewer people within the 300 metre corridor each side of the route centreline. Route C6 had significant advantages in engineering terms in that it has the best earthwork balance. Further the route is preferred in hydrogeological terms in that it does not cross any reported groundwater resources, whereas Routes C3 and C5 cross major gravel acquifers between Maganey and Knockarda and south of Newtownallen respectively.
With Route C6 selected, the choice north of Carlow was thus reduced to Route A1 plus B3 or Route A5 plus B5 and these routes were evaluated further as Route 9 and Route 10.

Step 5: Selection matrices were prepared for the remaining overall Route Options (Routes 9 and 10) together with Traffic/Cost-Benefit/Socio-Economic Impacts see RSR2 figure 17.5 and table 17.10 of Volume 2. This enabled a Preferred Route from Kilcullen to south of Carlow to be identified.

The Routes 9 and 10 were identical south of Carlow and were tested to assess the advantages and disadvantages of a route following the N9 corridor (Route 9) or going via Athy (Route 10). Route 9 included as part of the scheme, the cost of a high standard single carriageway link from the N9/N10 scheme to Athy with a connection eastwards to the R747 near Ballitore. In environmental and engineering terms the analysis showed that the differences between the two routes were generally not significant.

The traffic and cost-benefit analysis showed that volume of traffic attracted to Route 10 was marginally higher than to Route 9. However the discounted travel and accident benefits were significantly higher for Route 9 than for Route 10. This is due to the extra distance traffic has to travel between Carlow and Kilcullen using Route 10 via Athy. It results in a reduction of the Benefit to Cost Ratio from 2.01 to 1.66.

In socio-economic terms it was concluded that, with the high standard Athy to R747 Link Road, Route 9 would bring major socio-economic benefits to Athy. Route 9 would provide most of the benefits that would accrue from implementation of Route 10.

Based on this analysis, Route 9 was selected as the draft Preferred Route because of its significantly better economic performance compared with Route 10.

Step 6: Selection matrices for the remaining combination of routes in Selection D were prepared for those options which connected to Route Corridor E1 which was the emerging Preferred Route Corridor in the southern section of the study area.

South of Carlow Route D3 affected less properties than Route D4 and was selected. As Route E1 was emerging as the Preferred Route south of Paulstown, see Volume 3, a final comparison was completed and is shown in table 17.8 of Volume 2. This compared a new connector between Route D3/D2 and Route D4 (i.e. via node 33) with an alternative route using the E1/E6 connector (i.e. via node 36). The comparison showed that the route via node 33 had less impact in terms of properties affected and was chosen in preference to the route using connector E1/E6.

Step 7: Where possible the draft Preferred Route Corridor was adjusted to reduce the impacts further. Preliminary junction locations and layouts further. Preliminary junction locations and layouts were developed and link roads were included.

The draft Preferred Route Corridor was adjusted in four main locations prior to the Preferred Route being exhibited at Public Consultation No. 3. The amendments were made primarily to reduce the impacts on residential and other property following examination of available material from Public Consultation No. 2 and extensive site visits. The main four locations were:

• Crookstown Lower to Belan
  
• Belan to Prumpelstown
  
• Bennekerry to Tinryland
  
• Clonmelsh to Powerstown
  

Athy to R747 Link Road
As described earlier a high quality link road was included in the draft Preferred Route to improve, significantly, the standard of road connections between Athy and the National Primary Road Network. Four options for the alignment of the Link Road were investigated and an option selected which avoided demolition for properties and reduced farm severance by adopting an 1.8km length on the existing Country Road.