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Naturalistic Driving observation refers to studies undertaken using unobtrusive observation when driving in a natural setting. Both, Naturalistic Driving Studies and Naturalistic FOTs use this type of observation. Naturalistic Driving observation is a new approach among already applied traffic research methods.

The concept of NDS

In Naturalistic Driving Studies (NDS), the driver becomes unaware of the observation as the data collection is organised as discreet as possible and preferably drivers use their own vehicles. The data is used to study the relationship between driver-, vehicle-, and/or environment factors with crash risk.

NDS provide information that is difficult or even impossible to obtain by other research methods. For example, analyses of crash statistics or in-depth crash investigation can hardly provide information about behavioural issues preceding a crash (e.g. on risk factors such as distraction and fatigue). Observations by means of vehicles with visible instruments or simulators do not encourage the test subjects to behave in a normal (naturalistic) way, since they are generally well aware of the experimental conditions. Experience shows that during the naturalistic observations which use the subjects’ own car equipped with monitoring devices, drivers quickly forget the presence of cameras and sensors, allowing the study of real-world conditions driving behaviour.

Compared to NDS, Field Operational Tests are using quasi-experimental methods (e.g. comparing data from baseline and treatment phase, i.e. data collected with systems switched off and on) and aim at evaluating certain functions (e.g. driver assistance systems). If NDS and FOTs are regarded as two ends of a continuum, Naturalistic FOTs are lying somewhere in between. They are using unobtrusive observation in a natural setting to evaluate the relationship between driver-, vehicle-, and/or environment factors with crash risk, driving behaviour, and the effectiveness of driver assistance functions. Thus, Naturalistic FOTs combine elements of both NDS and FOTs.

The naturalistic driving observation as a method requires heavy resources in terms of samples and duration (in order to assure the appearance of crashes and near crashes in the data collected). Thus, also large resources for data gathering, data storage, data reduction, and analysis are needed. Therefore, it is of crucial importance to ensure that such a study is broadly supported and that the results can serve many purposes.


In particular in the US, many Naturalistic Driving Studies have been conducted so far (for example the 100 cars study, the Commercial Vehicle Operations study and the ongoing Strategic Highway Research Programme - SHRP2).

For Europe, it is a relatively new field. Forerunner is Sweden with SAFER, the Vehicle and Traffic Safety Centre at Chalmers University, where activities in particular aim at further elaborating a Naturalistic FOT methodology. The most prominent project in this regard is SeMiFOT (Sweden-Michigan Field Operational Test) which focused on further developing the Naturalistic FOT method into a powerful tool for a) accident research, b) evaluation of safety, efficiency, and usage and acceptance of driver assistance systems, and c) countermeasure innovation and development. SeMiFOT has provided valuable input for the methodology used in – among others – the two currently ongoing pan-European FOT projects euroFOT and TeleFOT.

The data collected in SeMiFOT – which was finished in 2009 – will be further analysed in the continuation project SeMiFOT2. Main research topics are exploring new statistical approaches for the analysis of Crash-Relevant Events, e.g. extreme value theory, further analysis of the impact of visual behaviour and the development of events-prevented simulation techniques.

On the European level, two projects need to be mentioned here: The 2BeSafe NDS, which is the first one to collect data on powered two-wheelers on a large scale (and in four European countries). And the PROLOGUE project that aims at giving recommendations and providing an outline for a large-scale naturalistic study in Europe.

Although NDS and Naturalistic FOTs might aim at different purposes (understanding the factors leading to accidents/incidents versus evaluating ITS applications) there certainly is a close link on the Naturalistic methodology part where both types of projects share common issues of data acquisition, data storage, and data analysis.

Source of information

FOT-Net Brochure, November 2010

List of NDS FOTs

"NDS" is a category of the FOT Catalogue. To see the full list of FOTs by countries, go back to the FOT Catalogue. To look at other FOT Categories, see also the the catalogue of FOTs by categories.

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