Assessment process
Environment, engineering and traffic and economic impacts of the Scheme Options have been assessed as part of DMRB Stage 2, which has now been completed. Environmental, engineering, traffic and economic assessments will also inform the development of the preferred route at DMRB Stage 3, which will be reported in an Environmental Impact Assessment Report and other Stage 3 Reports.
Environmental assessment
The environmental assessment considers the following topics:
- Air quality: Traffic-related changes at sensitive receptors (e.g. residential areas, schools, hospitals).
- Noise and vibration: Traffic-related changes at sensitive receptors (e.g. residential areas, schools, hospitals).
- Population and human health: Land-use changes, agriculture and forestry effects, walkers, cyclists and horse riders, and severance of routes used by the community. Travellers using the new road.
- Materials assets and waste: Material resources, waste management.
- Cultural heritage: Archaeological remains, battlefields, landscapes and historic buildings.
- Landscape and visual: Landscape character (including designated areas), effects on topography and potential visual impacts affecting views from properties and on people outdoors.
- Geology and soils: Geological and soil resources, including designated sites. Groundwater, private water supplies, other sources of drinking water.
- Road drainage and the water environment: Flooding and flood risk, water quality, drainage and river processes, forms and sediments.
- Major accidents and disasters: Considers the vulnerability of scheme to risks from either major accidents or disasters.
- Biodiversity: Effects on designated ecological sites, and on important habitats (including rivers and woodlands) and species.
- Effects on climate: Considers the climate emissions assessment, i.e. the potential effects to the climate.
- Climate vulnerability: Considers the impact of climate change and associated extreme weather in the context of the scheme.
Engineering assessment
The engineering assessment considers the following topics:
- Local roads and accesses: The impact on local roads and accesses which connect directly with the A83 carriageway or alternatively run adjacent to the A83 carriageway.
- Construction duration: The length of time required to construct each of the scheme options.
- Resilience: Events on Beinn Luibhean slope: Resilience relates to the closure of the A83 resulting in diversions for road users. This includes risk of unplanned closures due to external factors, but specifically landslide events at Beinn Luibhean.
- Alignment with standards: Considers the alignment of the design with the relevant engineering standards, including an assessment of where refinement of standards have been incorporated whilst still providing a safe and resilient solution.
- Topography and land use: Considers how the scheme options interface with the existing topography and land use.
- Geotechnics and earthworks: Complexity and extent of geotechnical works.
- Hydrology: Considers the complexity of the drainage system and culverts noting other hydro/hydromorphology elements are considered in the environmental assessment.
- Structures: All scheme options include for a significant number of structures including bridges, underpasses and retaining structures. This factor considers the design complexity of said structures both in relation to construction and maintenance.
- Utilities: Considers the impact of underground and overhead Public Utilities within the extents of the project, including the provision of services to support construction and operation.
- Constructability (disruption): Considers disturbance to road users during construction.
- Operation and maintenance: Considers the impacts of operation and maintenance interventions to structures, tunnels, flow shelters and engineered slopes.
Traffic and economic assessment
The traffic and economic assessment considers the traffic and economic performance of the Scheme Options, including consideration of the ways the options improve the resilience, safety and operation of the route.
The A83 is considered key infrastructure in supporting the wider national economy through; connecting businesses and communities, facilitating access to essential services, and supporting jobs and activities in industries such as healthcare, education, aquaculture, forestry, tourism, energy and renewables. Therefore, consideration of the wider economic benefits also forms a key part of the assessment.