Preliminary Options Report Scheme Assessment Report 1 - Constraints Report 3 Description of Alternative Schemes 3.1 The Study Area In order to identify a route for the A5WTC, extensive consultation and investigation is required in order to ensure that all pertinent environmental and engineering constraints are considered and for this reason it is necessary to identify a study area that covers a sufficiently large geographical area at the outset of the assessment process. In the case of the A5WTC the general centreline of the study area was largely dictated by the overriding requirement that the route should generally follow the existing established transport corridor, and in so doing link the main centres of population along the route (i.e. Aughnacloy, Omagh, Strabane and Londonderry). There was also a requirement for the A5WTC to link in with the A4 (which is currently being upgraded to dual carriageway standard) close to the village of Ballygawley and in so doing open up an improved East–West Link to Belfast. The engineering study area was determined by reference to mapping, carrying out site visits and taking into account areas of settlement, very high and steep ground, major watercourses and the border. This boundary was an initial assessment and was refined during the assessment period to reflect a greater knowledge of particular locations. The environmental constraints study area was determined to ensure that all major constraints that could impact on or be impacted on by the new road would be identified and recorded. This study area crosses the border to allow the identification and assessment of trans-boundary effects in accordance with environmental legislation. The process of identifying a route is developed in 3 stages each involving a progressive degree of refinement and this report deals with Stage 1. For the Stage 1 Assessment an engineering study area was identified based on the criteria that it should represent the area within which feasible corridor options are likely to exist and is shown in Figure 3.1 to 3.3 and in Drawings 796036-0800-D-00310 to 796036- 0800-D-00319 in Volume 2 and is discussed below. 3.2 Corridor Evaluation - Craigavon Bridge (Londonderry) to New Buildings The existing A5 between Craigavon Bridge and New Buildings occupies a very confined alignment fitting between the River Foyle and playing fields on the west and the linear development to the east at the foot of Clondermont Hill. There is little or no land (that is not developed in some manner) through which an upgraded road alignment of dual carriageway standard could relatively easily be provided. Currently there are a number of direct accesses for both side roads and private accesses onto the A5 with permitted right turns onto and off the road. 796036/0000/R/006 Version 3 70 ©Mouchel 2008 Preliminary Options Report Scheme Assessment Report 1 - Constraints Report Under a separate study, Roads Service is currently assessing the strategic traffic needs of the City of Derry and its environs including the traffic desire lines from the A5 into the city and the connections to the remainder of the strategic road network on both sides of the River Foyle. Until the results of this study are known, the future traffic movements and flows along the A5 north of New Buildings cannot be determined which in turn means that the carriageway standard required to meet future needs is not identifiable. The current approach to this section of the existing A5 between Craigavon Bridge and the northern development limits of New Buildings is that an assessment of the existing single carriageway will be carried out in due course and further traffic management/ traffic calming measures identified and implemented to enable the network to operate as safely and efficiently as possible as traffic flows increase. Such works are considered to be outside the scope of the A5WTC project. This assessment hereafter therefore does not consider corridors between Craigavon Bridge (Londonderry) and New Buildings. 3.3 Description of Alternative Corridors The Design Manual for Roads and Bridges requires the Stage 1 Assessment of road improvements to identify and consider broadly defined improvement strategies referencing major features as appropriate. In the case of the A5 WTC three principal improvement strategies were considered namely: • West of the A5, • Utilising the existing (A5) corridor, • East of the A5. For Stage 1, these three strategies were developed into a number of corridors that could improve the link between Londonderry, Strabane and Omagh, and provide a strategic link between Co. Monaghan and Co. Donegal - refer to Drawing Numbers 796038-0800-D-00310 to 00319 incl. These corridors were each developed initially through a process of considering engineering constraints such as properties and topography. Engineering and Environmental constraints identified within the two study areas are reported within Chapters 4 and 5. Due to the overall length of the scheme it has been decided for the purposes of this report to divide the engineering study area into 3 sections (i.e. Section 1 – New Buildings to South of Strabane, Section 2 – South of Strabane to South of Omagh and Section 3 – South of Omagh to Aughnacloy). 796036/0000/R/006 Version 3 71 ©Mouchel 2008 Preliminary Options Report Scheme Assessment Report 1 - Constraints Report To assist the identification, development and assessment of corridors a system of nodes has been developed. These nodes are shown on the drawings listed above and are referenced in the subsequent text. 796036/0000/R/006 Version 3 72 ©Mouchel 2008 Preliminary Options Report Scheme Assessment Report 1 - Constraints Report 796036/0000/R/006 Version 3 73 ©Mouchel 2008 Preliminary Options Report Scheme Assessment Report 1 - Constraints Report 3.4 Corridor Evolution – New Buildings to South of Strabane The following text describes the development of potential corridors within Section 1 – New Buildings to South of Strabane. To minimise repetition, corridors have been described by sub-section, namely sections 1A, 1B and 1C. For a graphical representation of the corridors please refer to drawing numbers 796036-0800-D- 00310 to 00312 inclusive and figure 3.1. 3.4.1 Sub-Section 1A: New Buildings to Cloghcor In this sub-section five corridor links have been developed, namely: • West of existing A5 at New Buildings (node 101) to Drumenny (node 103) via Bready (node 102); • The existing A5 from New Buildings (node 101) to Loughneas (node 108) via Bready (node 102); • East of the existing A5 at New Buildings (node 101) to Loughneas (node 108) via Eden (node 107); • East of the existing A5 at New Buildings (node 101) to Milltown Burndennet (node 115) via Eden (node 107); • East of existing A5 at New Buildings (node 114) to Milltown Burndennet, (node 115). These corridor links are located in drawing 796036-0800-D-00310 to 00312 West of the existing A5 at New Buildings (node 101) to Drumenny (node 103) via Bready (node 102) - route corridor options S1A01, S1A02, S1A03 From a point southwest of New Buildings the corridor link extends in a south westerly direction past Magheramason, with the eastern fringe roughly defined by the existing A5, with the western extents approximate to the boundary of the potential River Foyle Floodplain. The 1km wide link remains to the immediate west of the existing A5 to a point to the west of Bready. Continuing in southerly direction from Bready the link extends to the community of Drumenny where the link spans the zone between the River Foyle and the existing A5. The existing A5 from New Buildings (node 101) to Loughneas (node 108) via Bready (node 102) - route corridor options S1B01, S1B02, S1B05, S1H08, S1H09, S1H10 This corridor link is centred about the existing A5 and extends from New Buildings in a south-easterly direction to Magheramason and Bready before turning south to a point west of Loughneas. The existing A5 is discussed in more detail in Chapter 2. 796036/0000/R/006 Version 3 74 ©Mouchel 2008 Preliminary Options Report Scheme Assessment Report 1 - Constraints Report East of existing A5 at New Buildings (node 101) to Loughneas (node 108) via Eden (node 107) - route corridor options S1B03, S1B04, S1B06 This corridor link extends in a south-westerly direction from New Buildings to the east of Magheramason before turning south in the region of Cloghogle towards Eden. The topography of the proposed corridor varies significantly as it climbs and then runs parallel to the lower slopes of Gortmonley Hill. From Eden the corridor link extends in a south-westerly direction towards Loughneas; its western fringe being defined by the existing A5. East of the existing A5 at New Buildings (node 101) to Milltown Burndennet (node 115) via Eden (node 107) - route corridor options S1H01, S1H02, S1H03, S1H04, S1H05, S1H06, S1H07 This corridor link extends in a south-westerly direction from New Buildings to the east of Magheramason before turning south in the region of Cloghogle towards Eden. The topography of the proposed corridor link varies significantly as it climbs and the runs parallel to the lower slopes of Gortmonley Hill. From Eden the corridor link heads in a south-easterly direction towards Donagheady then on to Milltown Burndennet; high voltage overhead cables are present at the southern extent of the link. East of existing A5 at New Buildings (node 114) to Milltown Burndennet, (node 115) - route corridor options S1C01, S1C02, S1C03, S1C04, S1C05, S1C06, S1C07 This corridor link extends from the eastern fringe of New Buildings in a south- easterly, then southerly direction centred about the existing B48, through the Burngibbagh valley to a point near Ardmore. From this point the corridor link continues, following the line of the high voltage power lines in a south-westerly direction to Milltown Burndennet via Donagheady.