From the official road accident statistics, only limited information can be analysed on accident occurrence, accident sequence, injury mechanisms and consequences of road accidents. In order to meet the research needs of legislators and industry, more in-depth information are required. This gap will be closed by specially equipped and trained survey teams collecting and anonymously documenting a representative subset of all traffic accidents with personal injury reported by the police at two survey locations in Germany, independent of the police objective, according to purely scientific aspects. In the process, up to 3,500 individual pieces of information per accident are collected and photos are systematically taken, which are compiled in a case file.

The study is subject to a sampling plan, as a 24/7 data collection is not cost-efficient. The data collection is divided into blocks of 6 hours each, of which 2 are operated per day (00:00 to 6:00 and 12:00 to 18:00 or 6:00 to 12:00 and 18:00 to 24:00). The division of the blocks alternates on a weekly basis and is also coordinated among the contractors. If an accident is reported via the police control centre within a survey block, the teams consisting of technical and medical personnel travel to the accident site.

Essential for a later reconstruction and analysis is the comprehensive recording of all the circumstances surrounding the accident under consideration. For this purpose, information is obtained at different levels: the description of the course of the accident, the type and kind of accident; sketches of the directions of travel, collision and end positions; characteristics of the persons involved - medical data of the persons involved in the accident and, if applicable, technical data of their vehicles. The course of the rescue chain, the securing of the accident site and the traffic flow at the time of the accident are also recorded. Some of the recording levels are examined in more detail below.

Data protection
Data protection is extremely important for such a scientific study. In the GIDAS database, all information is anonymised. Names, addresses, dates of birth, etc. of the persons involved in the accident are not stored. Every effort is made to make it impossible to identify specific accidents and those involved. Precise accident times, number plates, chassis numbers, etc. are also not stored. In all pictures, the faces of those involved, licence plates and special features such as imprints on vehicles are made unrecognisable.

The environment
For the most accurate reconstruction possible, the teams document all environmental and road conditions on site. Not only visibility conditions, but also road data such as road geometry, condition, temperature as well as gradient conditions, water film heights and traffic regulations are recorded. The environmental information is also relevant for assessing the general conditions of accidents.

Participants
In addition to basic information on the age and gender of a person involved in an accident, data on driving licence ownership, any restrictions such as illnesses and stress factors, but also driving experience and distractions are important. A psychological interview of those involved provides further information about the accident. If the situation allows, the accident is reviewed together with the person involved. Often it is possible to obtain indications about the causing weak point in the interaction between human, environment and technology. With the consent of those involved, injury diagnoses and treatment measures in the hospital are included in the file. This expanded view of what happened, also with regard to the rescue chain immediately after the accident, also enables hospitals and paramedics to improve their actions. With the accident data collected, a reconstruction of the course of the accident is made. On the basis of the accident sketch, it is possible to reproduce how the accident took place in terms of driving dynamics and biomechanical load dynamics. Parameters such as visual relationships and force impacts are also made visible.