Scale plan preparation
The site of the accident is surveyed and a scale plan is prepared from the measurements obtained in the survey.
Survey data is imported into a computer aided design programme and the plan is the output from that programme.
Most police forces are equipped with total station theodolites and they sometimes produce accurate scale plans which are made available to clients.
Site-centred Ordnance Survey Superplans can be used as the basis of a scale plan prepared in connection with an accident investigation. Ordnance Survey plans do not include road markings nor street furniture. That information has to be added to the plan along with accident details such as tyre marks, debris, and vehicle locations.
Google Earth and Google Street View are now invaluable sources of information about accident sites.