Glossary of Terms
Above Ordnance Datum (AOD)
The mean sea level at Newlyn (UK) used as a base measurement on Ordnance Survey Maps for contours.
Allocation
A proposal for land for housing, industry or other uses within a Local Plan that identifies a specific area of land to be developed within the time period of the plan.
Alluvium
Sediment deposited by a river.
Assessment
An umbrella term for description, analysis and evaluation.
Attenuation
Increase in duration of flow hydrograph with a consequent reduction in peak flow.
At-grade junction
A junction arrangement at which two or more roads meet at the same level.
Baseline
The existing conditions which form the basis or start point of the assessment.
Bedrock
Hard rock that lies beneath a superficial cover of soils and sediments.
Benefit to Cost Ratio (BCR)
An indicator, used in the formal discipline of cost-benefit analysis, that attempts to summarise the overall value for money of a project or proposal. A BCR is the ratio of the benefits of a project or proposal, expressed in monetary terms, relative to its costs, also expressed in monetary terms.
Biodiversity
Biological diversity, or richness of living organisms present in representative communities and populations.
Bund
An embankment, wall or dam that can be used to minimise noise or alternatively built around an oil tank to contain the contents in the event of spillage.
Compulsory Purchase Order (CPO)
A legal document giving the government (Scottish Ministers) power to compulsory purchase the areas of land necessary for the construction of the scheme.
Culvert
A metal, wooden, plastic, or concrete conduit through which surface water can flow under or across roads.
Cutting
Typically where the ground/earth is cut out to make way for a road or railway line.
Diverge
A link road departing the main carriageway to a subsidiary road or junction.
Do-minimum
The base situation where there are no modifications to the existing road network. May also refer to the minimum modifications, which will necessarily take place in the absence of a proposed scheme
Do-Something
The proposed scenario involving construction of the proposed Pass of Birnam to Tay Crossing scheme.
Effect
The result of change or changes on specific environmental resources or receptors.
Element
A component part of the proposed scheme (e.g. road, structure, lay-by).
Environmental Impact Assessment (EIA)
The process by which information about the environmental effects of a project is evaluated and mitigation measures are identified.
Fill
Material deposited by man in ground depression or excavated area or to construct an embankment.
Floodplain
Land adjacent to a river which is subject to regular flooding.
Geomorphology
The branch of geology concerned with the structure, origin and development of topographical features of the earth’s crust.
Glaciofluvial
Pertaining to streams fed by melting glaciers, or to the deposits and landforms produced by such streams.
Glacial Till
Glacial till is that part of glacial drift which was deposited directly by the glacier. It may vary from clays to mixtures of clay, sand, gravel and boulders.
Grade Separated Junction
A junction arrangement that is separated by level from the through carriageway.
Ground Investigation
Exploratory investigation to determine the structure and characteristics of the ground influenced by a development. The collected information is used to establish or predict ground and groundwater behaviour during, and subsequent to, construction.
Groundwater
Water below the surface of the ground in the saturation zone and in direct contact with the ground or subsoil.
Habitat
Term most accurately meaning the place in which a species lives, but also used to describe plant communities or agglomerations of plant communities, as used, for example in a Phase 1 Habitat Survey.
Heavy Goods Vehicle (HGV)
Vehicles with 3 axles (articulated) or 4 or more axles (rigid and articulated).
Hydrogeology
The branch of geology that deals with the occurrence, distribution, and effect of ground water.
Hydrological
The exchange of water between the atmosphere, the land and the oceans.
Impact
Any changes attributable to the proposed scheme that have the potential to have environmental effects (i.e. the causes of the effects).
Impermeable
Material that does not allow fluids to pass through it.
Infrastructure Investment Plan (IIP)
A Scottish Government document that sets out priorities for investment and long–term strategy for the development of public infrastructure in Scotland.
Landform
Combination of slope and elevation producing the shape and form of the land surface.
Landscape
Human perception of the land, conditioned by knowledge and identity with a place.
Listed Building
Building included on the list of buildings of special architectural or historic interest and afforded statutory protection under the ‘Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997’ and other planning legislation. Classified categories A – C(s).
Local Road
An A, B or C classified road (non Trunk Road) typically operated by a local authority.
Loop
A connecting road, utilising a continuous curve in the connection of two roads within a junction which passes through an angle in the range of approximately 180 to 270 degrees.
Made Ground
Material deposited by man i.e. not natural.
Mainline
The principal road being considered, namely the A9 or the road proposed as its replacement.
Merge
A link road accessing the main carriageway from a subsidiary road or junction.
Mitigation
Term used to indicate avoidance, remediation or alleviation of adverse impacts.
Native
A species occurring naturally, in its normal geographic range.
Net Present Value (NPV)
The total present value of a time series of cash flows. It is a standard method to use the time value of money to appraise long-term projects.
Non-Motorised User (NMU)
Term previously used to describe road users other than vehicular traffic, particularly cyclists, pedestrians and equestrians.
Peat
Material consisting of decomposed vegetation forming a deposit found in bogs.
Runoff
Water that flows over the ground surface to the drainage system. This occurs if the ground is impermeable or if permeable ground is saturated.
Scheduled Monument
A monument which has been scheduled by the Scottish Ministers as being of national importance under the terms of the ‘Ancient Monuments and Archaeological Areas Act 1979’.
Severance
The separation of communities from facilities and services they use within their community. Alternatively, in relation to agricultural land, the division of plots of land into separate land parcels, potentially affecting access or creating areas that may be impractical for agricultural use.
Sites of Special Scientific Interest (SSSI)
Areas of national importance. The aim of the SSSI network is to maintain an adequate representation of all natural and semi-natural habitats and native species across Britain. The site network is protected under the provisions of Sections 28 and 19 of the Wildlife and Countryside Act 1981 as well as the Amendment Act 1985 and the Environmental Protection Act 1990.
Slip Road
A connector road facilitating access between one road and another.
Special Area of Conservation (SAC)
An area designated under the EC Habitats Directive to ensure that rare, endangered or vulnerable habitats or species of community interest are either maintained at or restored to a favourable conservation status.
Strategic Environmental Assessment (SEA)
The process by which information about the environmental effects of proposed plans, policies and programmes are evaluated.
Strategic Transport Project Review (STPR)
A review of the Scottish transport network undertaken by Transport Scotland and published in 2008. It identifies and prioritises road, rail and other interventions of national significance, proposed to be taken forward to improve the network.
Superficial Deposits
The youngest geological deposits formed during the most recent period of geological time, the Quaternary, which extends back 1.8 million years from the present.
Sustainable Drainage Systems (SuDS)
A sequence of management practices and control structures designed to drain and treat surface water in a more sustainable fashion than some conventional techniques.
Trunk Road
Part of the road network connecting major cities, towns, airports and ports for which the Scottish Government is responsible.
Vulnerable users
Children, the elderly and disabled people.
Walkers, Wheelers, Cyclists and Horse Riders (WCH)
Road Users other than vehicular traffic, including walking or wheeling unaided, using any kind of wheeled mobility aid including wheelchairs, mobility scooters, walking frames, prams or buggies, cyclists (including e-bikes) and horse-riders.
Water Quality
The chemical and biological status of various parameters within the water column and their interactions, for example dissolved oxygen, indicator metals such as dissolved copper, or suspended solids (the movement of which is determined by hydrological process and forms geomorphological landforms).