User preferences, driving context or manoeuvre characteristics? Exploring parameters affecting the acceptability of automated overtaking.

Future user acceptance will be a requirement for the AVs to accomplish their estimated safety benefits, highlighting the importance of acceptable driving behaviour. This study aims to investigate the parameters that affect the acceptability of highly automated overtaking. 237 respondents participated in a video based online survey, rating different motorway flying overtaking scenarios based on their preferences. The scores were analysed using a variety of methods (statistical tests, Principal Component Analysis, Linear Mixed Models). Long pull-out distances and manoeuvre duration values, as well as lower speeds were preferred by the participants, with some limited impact of the driving situation. Overall, behaviour simulating an average, cautious human driver is likely to positively influence acceptability and suggests the value of further research on context-adaptive automated driving to account for subjective risk perception. These findings can contribute towards user-centred systems that assist or autonomously perform overtaking manoeuvres, supporting their uptake and thus the realisation of their safety benefits.

The influence of social context on the perception of assistive technology: using a semantic differential scale to compare young adults' views from the United Kingdom and Pakistan.

Background and aim: A Society's view of disability may influence the perception and use of Assistive Technology (AT) products. Semantic cues or cultural coding provide the viewer with a series of visual stimuli to be given or ascribed meaning. Previous research has shown cognitive approaches to visual perception and assignment of meaning vary between diverse cultures. This study reviews the influence of contextual settings on perception, to provide the basis for a debate on the societal perception of communicative content (semantic/meaning) of an AT product; and, the relevance of different cultural cognitive styles. The paper explores, from a cultural viewpoint, the overall understanding of disability internationally.Method: A Semantic Differential (SD) scale was used to obtain views on the image of an attendant wheelchair from nine hundred and ninety-one (991) young adults from the United Kingdom (UK) and Pakistan (PAK), reflecting the individualist and collectivist societies, respectively. This survey follows a previous paper-based study using the same image and protocol. Comparing the two surveys, a consensus of views from the two groups was achieved.Results and conclusion: The responses from the UK group were skewed towards a negative view of disability compared to the Pakistan group. This inferred greater social stigma associated with this AT product in the UK. The combined findings from both surveys provide insights into societal perception of AT products and disability. Areas for future research are suggested, including what visual components of an AT product (graphemes) appear to be associated with positive or negative responses for collectivist and individual societal groups.Implications for rehabilitationAssistive Technology (AT) product designers, academics, professionals and stakeholders need to be aware of challenges which are originated from one's socio-cultural environment. AT products convey certain meanings, semantics, which are interpreted by the society and are subjective to a specific cultural setting.•For the effective communication of meanings and values an AT product relies on the visual clues and design features embedded within the design. However, there have been a limited number of studies reviewing this aspect of product semantics.•The survey and associated testing has highlighted the differences in cultural perception towards AT products and demonstrated the importance of effectively designing the semantic attributes of an AT product as well as its function.•The demonstration of the efficacy of methods within the study for exploring the interpretation of semantic attributes of AT products will help designers and developers better understand the perceptions of individual cultures and societal groups.•A better understanding of different cultures and societies will enable designers and clinicians who specify AT products to reduce AT product abandonment; and, the associated stigma around disability.

Time-to-collision analysis of pedestrian and pedal-cycle accidents for the development of autonomous emergency braking systems.

The aim of this study was to describe the position of pedestrians and pedal cyclists relative to the striking vehicle in the 3 s before impact. This information is essential for the development of effective autonomous emergency braking systems and relevant test conditions for consumer ratings. The UK RAIDS-OTS study provided 175 pedestrian and 127 pedal-cycle cases based on in-depth, at-scene investigations of a representative sample of accidents in 2000-2010. Pedal cyclists were scattered laterally more widely than pedestrians (90% of cyclists within around ±80° compared to ±20° for pedestrians), however their distance from the striking vehicle in the seconds before impact was no greater (90% of cyclists within 42 m at 3 s compared to 50 m for pedestrians). This data is consistent with a greater involvement of slow moving vehicles in cycle accidents. The implication of the results is that AEB systems for cyclists require almost complete 180° side-to-side vision but do not need a longer distance range than for pedestrians.

Pre-crash scenarios at road junctions: A clustering method for car crash data.

Given the recent advancements in autonomous driving functions, one of the main challenges is safe and efficient operation in complex traffic situations such as road junctions. There is a need for comprehensive testing, either in virtual simulation environments or on real-world test tracks. This paper presents a novel data analysis method including the preparation, analysis and visualization of car crash data, to identify the critical pre-crash scenarios at T- and four-legged junctions as a basis for testing the safety of automated driving systems. The presented method employs k-medoids to cluster historical junction crash data into distinct partitions and then applies the association rules algorithm to each cluster to specify the driving scenarios in more detail. The dataset used consists of 1056 junction crashes in the UK, which were exported from the in-depth "On-the-Spot" database. The study resulted in thirteen crash clusters for T-junctions, and six crash clusters for crossroads. Association rules revealed common crash characteristics, which were the basis for the scenario descriptions. The results support existing findings on road junction accidents and provide benchmark situations for safety performance tests in order to reduce the possible number parameter combinations.

Is naturalistic driving research possible with highly instrumented cars? Lessons learnt in three research centres.

This paper provides an overview of the experiences using Highly Instrumented Cars (HICs) in three research Centres across Europe; Spain, the UK and Greece. The data collection capability of each car is described and an overview presented relating to the relationship between the level of instrumentation and the research possible. A discussion then follows which considers the advantages and disadvantages of using HICs for ND research. This includes the obtrusive nature of the data collection equipment, the cost of equipping the vehicles with sophisticated Data Acquisition Systems (DAS) and the challenges for data storage and analysis particularly with respect to video data. It is concluded that the use of HICs substantially increases the depth of knowledge relating to the driver's behaviour and their interaction with the vehicle and surroundings. With careful study design and integration into larger studies with Low(ly) instrumented Cars (LICs), HICs can contribute significantly and in a relatively naturalistic manner to the driver behaviour research.

An approach to the derivation of the cost of UK vehicle crash injuries.

An approach to costing of road crash injury has been developed using data from a 'Willingness-to-pay' survey mapped to injuries listed in the Abbreviated Injury Scale 1998 Revision. The costs derived have been applied to a database of real-world crash injuries that have been collected as part of the UK Cooperative Crash Injury Study (CCIS). The approach has been developed in order to determine future research priorities in vehicle passive safety. When all injuries in all crash-types are examined, the results highlight the cost of 'Whiplash' in the UK. When more serious injuries are considered, specifically those at AIS 2+, the cost of head injuries becomes evident in both frontal and side impacts.

Requirements for the crash protection of older vehicle passengers.

This study compares injury outcomes in vehicle crashes involving different age groups of belted passengers. Two datasets were considered. Firstly, UK national data revealed that younger passengers are much more likely to be involved in crashes per million miles travelled compared to older passengers although older passengers are much more likely to be killed or seriously injured compared to younger passengers. Secondly, in-depth vehicle crash injury data were examined to determine some of the underlying reasons for the enhanced injury risk amongst older passengers. In crashes of approximately equal severity, the older passenger group were significantly more likely to be fatally injured in frontal crashes (p<0.001). However young passengers were as equally likely to be killed in struck-side crashes compared to the older group. The results also showed that older passengers sustained more serious injuries to the chest region in frontal crashes compared with the younger aged group (p<0.0001) and it is this body region that is particularly problematic. When the data were analysed further, it was found that a large proportion of passengers were female and that in the majority of cases, the seat belt was responsible for injury. Since by the year 2030, 1 in 4 persons will be aged over 65 in most OECD countries, the results suggest a need for intervention through vehicle design including in-vehicle crashworthiness systems that take into account reduced tolerance to impact with ageing.

The effect of height on injury outcome for drivers of European passenger cars.

Statistical analysis of the UK in-depth accident database has been used to establish the characteristics of the 'small driver' at increased risk of injury. Drivers less than 160 cm in height are shown to have a significantly higher than average probability of AIS 2+ head and AIS 2+ pelvis and lower extremity injury. Subject trials have been used to establish the seating preferences of small stature drivers together with a comparison group drawn from the population as a whole.

Belted driver protection in frontal impact--what has been achieved and where do future priorities lie?

Examining injuries to real people in real crashes is the most meaningful way to validate improvements in crashworthiness as well as to determine where future priorities lie. Examination of U.K national statistics showed that, coincident with the introduction of airbag/pretensioner restraints, there was a significant fall in the rates of killed/seriously injured car occupants as well as a significant fall in the number of car occupant fatalities. Interrogation of the UK in-depth crash injury data for belted drivers in frontal crashes between 20-70 km/h ETS showed substantial reductions in AIS 2+ injury to the head in newer cars. In the same sample of crashes, no corresponding reductions in AIS 2+ injury were found for the chest, thigh and leg.

An overview of requirements for the crash protection of older drivers.

For some time now, it has been recognised that a major shift is occurring in the population age distributions of most motorised countries resulting in a growing number of older persons with an increasing need for mobility. It is expected that the mobility of older persons will become even more reliant on the motor vehicle as European countries in particular undergo transitions towards decentralisation and suburbanisation and because of the well-established longevity factor. As a group, older drivers do not currently represent a major road safety problem in most Western societies when compared with other age groups such as the young. However, they are involved in significantly more serious injury and casualty crashes per head of population. Furthermore, as older drivers are likely to become a more significant problem in the years ahead, it is now necessary to examine some vehicle design factors that affect the safety of the older driver in a crash.