Services | Collision Risk Assessment

Collision Risk Analysis (CRA) or Collision Risk Modelling (CRM) is undertaken to assess the risk of key selected species of birds colliding with wind turbines i.e. when moving through the swept area.

CRM uses detailed ornithological data collected by field ornithologists through a program of vantage point surveys. The vantage point survey methodology sets out to establish what bird species are active within an area and how they use the area. This is achieved by recording observed bird flights (as flightlines), their duration and an estimate of flight height on to field maps. The bird species recorded are site-specific and based on known important bird populations identified through consultation with statutory consultees and a desk study at the start of a project, or through initial findings in the field. Species selected as target species for this type of assessment are typically raptors e.g. red kite, golden eagle and hen harrier, or wildfowl e.g. geese and swans and wading birds e.g. golden plover and lapwing.

The data collected from the vantage point surveys is stored within a Geographical Information System (GIS). Peak Ecology use ESRI ArcGIS 10, and each observed bird flight is represented by a flightline with associated attribute information. The data can then be used to assess collision risk through the use of the standard collision risk model (CRM) developed by Scottish Natural Heritage (SNH). height, and rotor.

The model uses data from the vantage points in conjunction with species-specific biometric information and wind farm specifications such as the number of turbines, and the radius of the hub, height and rotor. The output from the model is an assessment of the likely number of collisions per given time period, through direct collisions with the turbine blades for each bird species under investigation.

The collision risk modelling outputs are reported such that their time frame is meaningful to the species being affected, for example spring passage, breeding season, autumn passage or winter and then over the life span of the wind farm, typically 25 years.

In addition to the outputs for the collision risk model the GIS data is also used to report species-specific maps for inclusion in ornithological reports and EIAs and delivered to the client as a series of GIS layers on completion of the project.

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