Dream 3.0. Documentation of references supporting the links in the classification scheme

Both the Driving Reliability and Error Analysis Method (DREAM; Ljung, 2002) and the SafetyNet Accident Causation System (SNACS; Ljung, 2006) have been successfully used as tools for accident analysis in Sweden as well as in other European countries. While the drivervehicle/ traffic environment-organisation triad are used as frames of reference and the Contextual Control Model (COCOM; Hollnagel, 1998) is used to organise human cognition, the links in the classification schemes have not been established by referring to literature. The aim of this literature review is therefore to investigate the empirical support for the links in the classification scheme of DREAM 3.0 (an updated version of DREAM/SNACS)

On-to-off-path gaze shift cancellations lead to gaze concentration in cognitively loaded car drivers: A simulator study exploring gaze patterns in relation to a cognitive task and the traffic environment

Appropriate visual behaviour is necessary for safe driving. Many previous studies have found that when performing non-visual cognitive tasks, drivers typically display an increased amount of on-path glances, along with a deteriorated visual scanning pattern towards potential hazards at locations outside their future travel path (off-path locations). This is often referred to as a gaze concentration effect. However, what has not been explored is more precisely how and when gaze concentration arises in relation to the cognitive task, and to what extent the timing of glances towards traffic-situation relevant off-path locations is affected. To investigate these specific topics, a driving simulator study was carried out. Car drivers’ visual behaviour during execution of a cognitive task (n-back) was studied during two traffic scenarios; one when driving through an intersection and one when passing a hidden exit. Aside from the expected gaze concentration effect, several novel findings that may explain this effect were observed. It was found that gaze shifts from an on-path to an off-path location were inhibited during increased cognitive load. However, gaze shifts in the other direction, that is, from an off-path to an on-path location, remained unaffected. This resulted in on-path glances increasing in duration, while off-path glances decreased in number. Furthermore, the inhibited off-path glances were typically not compensated for later. That is, off-path glances were cancelled, not delayed. This was the case both in relation to the cognitive task (near-term) and the traffic environment (far-term). There was thus a general reduction in the number of glances towards situationally relevant off-path locations, but the timing of the remaining glances was unaffected. These findings provide a deeper understanding of the mechanism behind gaze concentration and can contribute to both understanding and prediction of safety relevant effects of cognitive load in car drivers

D7.3 Report on simulator test results and driver acceptance of PROSPECT functions

The process of developing new automotive systems includes various testing cycles to assure a save operation in traffic. Physical system testing on test tracks is very important for this purpose, but rather expensive and might only become possible in later stages of the development process. Using a virtual simulation environment offers a safe possibility of testing new systems in early stages of development. Aditionally, driver-in-the-loop tests at test track and in a virtual simulator make it possible to evaluate driver reaction and potential acceptance by the future users of those systems. Within PROSPECT the new functions are investigated under various aspects in several simulator studies and test track studies. This deliverable D7.3 gives detailed information of conduction and results of the each study. Three studies focus exclusively on the for Vulnerable Road Users (VRUs) specifically dangerous urban intersection scenarios. The first of those studies examines the driver behaviour in a turning situation when a byciclist might be crossing. The described phenomena are looked-but-failed-to-see and failed-to-look. The second study, which provides an initial step in this line of research, analyzed the acceptance of issued forward collision warning times. The positioning of the potential accident opponent and the subjective feeling towards the criticality of the situation by the driver were key parameters taken into account. Last, but not least the acceptance of an intersection assist autonomous emergency braking systems was tested regarding the acceptance of potential buyers. The study was run for five days in a row for each participant to be able to judge the behaviour in a comuting situation. Two studies focused on longitudinal scenarios. Both studies followed the same design, but one was conducted on a test track and the other one in a simulator. The main objective was to investigate drivers reactions to FCW warnings and Active Steering interventions in critical VRU scenarios in case of a distraction of the driver. Additionally, the test track study was used to validate the results from the simulator study. The results of those studies are the basis for a wide acceptance evaluation of the systems. No system is an asset in increasing road safety if it is not accepted by the user and therefore turned off, if it is not required the system to be default on in consumer tests. Complemented by an additional acceptance study where the participants had to give their opinion of those systems after they watched videos of dangerous situations, the acceptance was analyzed based on questionnaires developed in PROSPECT and reported in Deliverable 7.2. This wholistic approach allows an expert discussion on the potentials of the PROSPECT functions in the future

Improving the Evaluation Process for Active Safety Functions

The general aim of the present thesis was to improve key steps in the procedure for functional, formative evaluation of Advanced Driver Assistance Systems (ADAS). Five unresolved theoretical and empirical issues were identified and addressed. The first identified issue was the lack of a general conceptual framework for ADAS evaluation that can help formulate functional specifications and generate testable hypotheses on ADAS influence in critical driving scenarios. In response, a conceptual framework called Situational Control was developed.The second issue concerned the current ways in which crash data is used to specify ADAS evaluation scenarios. An improved methodology for linking a set of in-depth investigated case studies to a general crash type was developed and successfully tested. The third issue concerned the extent to which data from in-depth investigations of fatal crashes can be used to specify ADAS evaluation scenarios. Some countries have fully representative in-depth investigated datasets for this crash type, but their relevance for ADAS evaluation has not been investigated. An empirical study of causation information in fatal intersection crashes was performed. However, the information collected in these investigations was found to be limited in ways which made them less useful for defining ADAS evaluation scenarios. The fourth issue was whether sufficiently critical driving events that result in realistic driver responses can be created and repeated in driving simulator based ADAS evaluation. A study was performed in which two groups of drivers, one with and one without FCW, were exposed to repeated critical lead vehicle braking events. Results indicate that while creating a single surprise event is possible, interaction effects that compromise result generalizability occur when the critical event is repeated. The fifth issue concerned principles for how to assess the combined influence multiple ADAS when present in the same vehicle. A study of an FOT evaluated ADAS bundle consisting of FCW and ACC was carried out to empirically test whether existing conceptual models for calculating the combined effect of multiple safety functions were applicable. The results indicate that existing models were too simplistic to account for the complex modifications of driver behavior found in the data

Generalization of case studies in road traffic when defining pre-crash scenarios for active safety function evaluation

To define pre-crash scenarios for evaluation of active safety functions, data from crash investigations is often used. Typical data sources include official databases with police reported crashes (macroscopic data) and in-depth case studies (microscopic data). Macroscopic data is often representative but has little detail on causation, while the opposite is true of microscopic data. Combining the sources by coupling causation information from a set of case studies to a macroscopic crash type would therefore seem ideal. For the coupling to be valid however, it must be verified that the selected case study set is representative of the crash type. The aim of this study is to describe and test a new methodology for such verification by means of an intermediate layer of representatively sampled crash information (questionnaire responses from crash involved drivers). The methodology was applied to intersection crashes. For the data sets used, the similarity in crash causation for case studies and questionnaire crashes, together with the context similarity for questionnaire crashes and the macroscopic crash type, was sufficient to argue that the case studies were representative of the crash type. While results must be considered preliminary given the limited data sets used, the proposed methodology shows promise for future work related to defining pre-crash scenarios for ADAS evaluation. (C) 2010 Elsevier Ltd. All rights reserved

Improving the Evaluation Process for Active Safety Functions

The general aim of the present thesis was to improve key steps in the procedure for functional, formative evaluation of Advanced Driver Assistance Systems (ADAS). Five unresolved theoretical and empirical issues were identified and addressed. The first identified issue was the lack of a general conceptual framework for ADAS evaluation that can help formulate functional specifications and generate testable hypotheses on ADAS influence in critical driving scenarios. In response, a conceptual framework called Situational Control was developed.The second issue concerned the current ways in which crash data is used to specify ADAS evaluation scenarios. An improved methodology for linking a set of in-depth investigated case studies to a general crash type was developed and successfully tested. The third issue concerned the extent to which data from in-depth investigations of fatal crashes can be used to specify ADAS evaluation scenarios. Some countries have fully representative in-depth investigated datasets for this crash type, but their relevance for ADAS evaluation has not been investigated. An empirical study of causation information in fatal intersection crashes was performed. However, the information collected in these investigations was found to be limited in ways which made them less useful for defining ADAS evaluation scenarios. The fourth issue was whether sufficiently critical driving events that result in realistic driver responses can be created and repeated in driving simulator based ADAS evaluation. A study was performed in which two groups of drivers, one with and one without FCW, were exposed to repeated critical lead vehicle braking events. Results indicate that while creating a single surprise event is possible, interaction effects that compromise result generalizability occur when the critical event is repeated. The fifth issue concerned principles for how to assess the combined influence multiple ADAS when present in the same vehicle. A study of an FOT evaluated ADAS bundle consisting of FCW and ACC was carried out to empirically test whether existing conceptual models for calculating the combined effect of multiple safety functions were applicable. The results indicate that existing models were too simplistic to account for the complex modifications of driver behavior found in the data

Developing Theoretical and Empirical Definitions of Safety Problems in Driving Suitable for Active Safety Function Evaluation

In passive safety, the requirement specifications used for evaluation of protective functions are both standardised and specified at a high level of detail regarding evaluation scenario definition, performance metrics and pass/fail criteria. For active safety, while several propositions for evaluation scenarios have been made, neither these, nor performance metrics and pass/fail criteria have yet reached a similar level of detail and standardisation. The objective of this thesis is to address two underlying reasons for this difference. One is theoretical in nature. On a general level, a set of principles and concepts which capture the fundamental ideas of a field of science can be called a conceptual framework. For active safety function evaluation, such a framework is currently lacking. To address this issue, a conceptual framework called Situational control was developed. The framework integrates fundamental ideas relevant for active safety function evaluation into a holistic and practically applicable picture. Its applicability was demonstrated by applying it in the context of writing and implementing requirement specifications for active safety function evaluation.The second reason is of empirical character. To evaluate the extent to which active safety functions prevent and/or mitigate crashes, it is essential to characterize the sequence of events which leads to collisions in a way which includes information on causal factors. To do this, data from official databases (macroscopic data), and in-depth case studies is often used. Macroscopic data is usually statistically representative but has limited information on why crashes happen, while the opposite is true of case studies. Using the two in combination would therefore seem ideal. However, the principles for connecting them are far from clear and current approaches suffer inherent weaknesses. To address this issue, a generalization methodology which links information in case studies to macroscopic crash types, in a way which covers not only context but also causation similarity, was developed. The feasibility of the methodology was tested through application on three sets of intersection crash data. Results indicate that the methodology was sufficiently successful to warrant further exploration with larger data sets

Developing Theoretical and Empirical Definitions of Safety Problems in Driving Suitable for Active Safety Function Evaluation

In passive safety, the requirement specifications used for evaluation of protective functions are both standardised and specified at a high level of detail regarding evaluation scenario definition, performance metrics and pass/fail criteria. For active safety, while several propositions for evaluation scenarios have been made, neither these, nor performance metrics and pass/fail criteria have yet reached a similar level of detail and standardisation. The objective of this thesis is to address two underlying reasons for this difference. One is theoretical in nature. On a general level, a set of principles and concepts which capture the fundamental ideas of a field of science can be called a conceptual framework. For active safety function evaluation, such a framework is currently lacking. To address this issue, a conceptual framework called Situational control was developed. The framework integrates fundamental ideas relevant for active safety function evaluation into a holistic and practically applicable picture. Its applicability was demonstrated by applying it in the context of writing and implementing requirement specifications for active safety function evaluation. The second reason is of empirical character. To evaluate the extent to which active safety functions prevent and/or mitigate crashes, it is essential to characterize the sequence of events which leads to collisions in a way which includes information on causal factors. To do this, data from official databases (macroscopic data), and in-depth case studies is often used. Macroscopic data is usually statistically representative but has limited information on why crashes happen, while the opposite is true of case studies. Using the two in combination would therefore seem ideal. However, the principles for connecting them are far from clear and current approaches suffer inherent weaknesses. To address this issue, a generalization methodology which links information in case studies to macroscopic crash types, in a way which covers not only context but also causation similarity, was developed. The feasibility of the methodology was tested through application on three sets of intersection crash data. Results indicate that the methodology was sufficiently successful to warrant further exploration with larger data sets

Crash investigations for active safety: Meeting new demands on investigation methodology

Active safety systems are aimed at accident prevention, hence the knowledge required for their development is different from that required for passive safety systems aimed at injury prevention. Particularly, knowledge about accident causation is required. When looking at existing accident causation data, it is argued it fails to explain in sufficient detail how and why the accidents occur. Therefore, there is a need for detailed micro-level descriptions of accident causation mechanisms, and also of methodologies suitable for creating such descriptions. One study addressing these needs is the Swedish project FICA (Factors Influencing the Causation of Accidents and incidents), where an accident investigation methodology suitable for active safety is developed, and in-depth accident investigations following this methodology are carried out on-scene in the area of Gothenburg by a multidisciplinary team. A preliminary aggregated analysis of different cases show that the methodology developed is adequate for pointing out common contributing factors and devising principal countermeasures