James Lenard

Source of head injury for pedestrians and pedal cyclists: Striking vehicle or road?

The potential effectiveness of vehicle-based secondary safety systems for the protection of pedestrians and pedal cyclists is related to the proportion of cases where injury arises by contact with the road or ground rather than with the striking vehicle. A detailed case review of 205 accidents from the UK On-the-Spot study involving vulnerable road users with head injuries or impacts indicated that contact with the road was responsible in 110 cases. The vehicle however was associated with a majority of more serious casualties: 31 (vehicle) compared with 26 (road) at AIS 2+ head injury level and 20 (vehicle) compared with 13 (road) at AIS 3+ level. Further analysis using a multivariate classification model identified several factors that correlated with the source of injury, namely the type of interaction between the striking vehicle and vulnerable road user, the age of the vulnerable road user and the nature of injury.

Typical pedestrian accident scenarios for the development of autonomous emergency braking test protocols.

An increasing proportion of new vehicles are being fitted with autonomous emergency braking systems. It is difficult for consumers to judge the effectiveness of these safety systems for individual models unless their performance is evaluated through track testing under controlled conditions. This paper aimed to contribute to the development of relevant test conditions by describing typical circumstances of pedestrian accidents. Cluster analysis was applied to two large British databases and both highlighted an urban scenario in daylight and fine weather where a small pedestrian walks across the road, especially from the near kerb, in clear view of a driver who is travelling straight ahead. For each dataset a main test configuration was defined to represent the conditions of the most common accident scenario along with test variations to reflect the characteristics of less common accident scenarios. Some of the variations pertaining to less common accident circumstances or to a minority of casualties in these scenarios were proposed as optional or supplementary test elements for an outstanding performance rating. Many considerations are incorporated into the final design and implementation of an actual testing regime, such as cost and the state of development of technology; only the representation of accident data lay within the scope of this paper. It would be desirable to ascertain the wider representativeness of the results by analysing accident data from other countries in a similar manner.

Accidents, injuries and safety priorities for light goods vehicles in Great Britain

Abstract This study presents data on light goods vehicle (LGV) crashes. The data are derived from two main sources. The first source involves mass analysis of crashes involving LGVs recorded in the national British STATS19 accident database for 1994 to 2000. The second source involves analysis from an in-depth study of LGV accidents in Britain since the late 1980s. In total, in-depth data on almost 500 LGV crashes are considered. Three main issues are apparent. Firstly, there is an issue of crash compatibility between LGVs and passenger cars. The second issue involves restraint use among LGV occupants, since the in-depth data reveal that use is low compared with car occupants. The third issue is the implications of introducing a regulatory compliance crash test for LGVs.

The use of volumetric projections in digital human modelling software for the identification of large goods vehicle blind spots

The aim of the study is to understand the nature of blind spots in the vision of drivers of Large Goods Vehicles caused by vehicle design variables such as the driver eye height, and mirror designs. The study was informed by the processing of UK national accident data using cluster analysis to establish if vehicle blind spots contribute to accidents. In order to establish the cause and nature of blind spots six top selling trucks in the UK, with a range of sizes were digitized and imported into the SAMMIE Digital Human Modelling (DHM) system. A novel CAD based vision projection technique, which has been validated in a laboratory study, allowed multiple mirror and window aperture projections to be created, resulting in the identification and quantification of a key blind spot. The identified blind spot was demonstrated to have the potential to be associated with the scenarios that were identified in the accident data. The project led to the revision of UNECE Regulation 46 that defines mirror coverage in the European Union, with new vehicle registrations in Europe being required to meet the amended standard after June of 2015.

Occupant safety in modern passenger cars

A study was undertaken recently for the Federal Office of Road Safety in Australia of 150 modern vehicle crashes where at least one of the vehicle occupants was admitted to hospital. The types of injuries sustained by occupants of modern Australian passenger cars involved in road crashes (including points of contact within the vehicle) were assessed to provide direction for future improvements in occupant protection. Seat belt performance in all seating positions was of particular interest. While the limited number of cases did not permit a full and detailed statistical analysis of these data, the findings nevertheless show there is scope for improving occupant protection for drivers and passengers of modern passenger cars.

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.

Vector model of vehicle collisions for inferring velocity from loss of kinetic energy with restitution on residual crush surface

Abstract In the standard mathematical model that underpins the inference of velocity change from vehicle damage in road accident reconstruction, the point where the colliding bodies engage is taken to lie in the same location as the point of application of the average impact force, usually in the central region of the crush zone or on the residual crush surface. Mathematical and physical reasons suggest the fidelity of the model could be deepened by allowing for a separation of these points, for example by locating the impulse or average force in the central region of the crush zone and defining engagement (common velocity or rebound) relative to the crush surface. Refinement of the theory revealed that the solutions for the change of linear and angular velocity are unaffected. For long-running in-depth research studies, this means that historical calculations of velocity change (delta-V) and related analyses on such topics as injury risk curves, countermeasure effectiveness and accident scenarios are not potentially undermined. Relative and absolute velocity are however affected. This was illustrated using crash test data where adjustments of 6 and 12 cm resulted in changes of up to 4% in road speed.

Position and rotation of driver's head as risk factor for whiplash in rear impacts

Evidence suggests that head position increases risk of whiplash injury to vehicle occupants in rear impacts. The aims of this study were to collect exposure data on head position and rotation during naturalistic driving and to express this in the form of a parametric statistical model for use in computer simulations to optimize seat design for neck injury prevention. An instrumented vehicle equipped with an eye-tracker was used to collect digital readings that were complemented with a four-track video recording. Data from driving trials (approximately 30-60 minutes) were analyzed when the vehicle was stopped, stopping or moving slowly as these are thought to be manoeuvres where impact and hence neck injury risk is highest. It was found that the ‘t location-scale’ distribution provided best fit to the experimental data and that the measured interquartile range or central 50% of head movement in such manoeuvres was approximately ± 15 mm lateral, ± 10 mm longitudinal and ± 7.5 degrees left-right rotation. These ranges provide guidance on the degree of biofidelity required in computer simulation models. Further analysis showed that out-of-range head rotation and rapid rotation explained the majority of missing digital readings and these two motions should therefore be modeled separately as elements of the parametric model.