A6 Toome Bypass - Key Features
Environment
Careful construction practice will protect this environmentally sensitive area which has Area of Special Scientific Interest (ASSI), Special Protection Area (SPA) and RAMSAR designations. 'Local Provenance' planting of native trees, shrubs and grasses will enhance and maintain local character and conservation value and will help integrate the bypass into the flat landscape.
Archaeology
There is evidence of early habitation alongside the river and significant archaeological finds have previously been made close to the river. An archaeologist will monitor the construction work and will take appropriate measures to record, remove or protect substantial finds.
Ecology
Careful construction practice and 'sustainable drainage' practice will protect the Lower River Bann from any harmful effects. Sustainable Drainage Systems (SUDS) using filter strips and swales, permeable surfaces and filter drains, infiltration devices, basins and ponds:
- Deals with runoff close where the rain falls
- Manages potential pollution at its source
- Protects water resources from point pollution (such as accidental spills) and diffuse sources.
Ground Engineering
Innovative design solutions will overcome the difficulties of building roads over the soft alluvial clays in the Lower Bann floodplain.
Lower River Bann Bridge
A single span 'Bowstring Girder' bridge will carry the bypass over the Lower River Bann. This landmark structure, which will become a prominent feature in the local landscape, allows the approach embankments to be kept low whilst ensuring that the river continues to be navigable. Abutments are set back from each river bank to maintain the integrity of the river habitat and allow free passage for anglers and ramblers. The steel deck will be fabricated by Fairfield Mabey at their Chepstow works and transported by road to the site. Temporary supports in the river will simplify the construction of the bridge; these will be removed when the steel deck has been assembled.
