Developments in the risk of crash involvement and injury to car occupants by model year using vehicle specific exposure data

Crash test based consumer information systems, such as EuroNCAP or US NCAP, have indicated a substantial reduction in the risk of serious injury to car occupants since the mid-1990s. In parallel with these improving experimental results, there has been a steady reduction in the total numbers of car occupants seriously or fatally injured and it has been generally assumed that improved crash protection accounts for much of the reductions observed societally. Nevertheless, there has been very little analysis of the relationship between experimental results and any real reductions in casualties because of the influence of confounding effects of other parameters including the exposure to risk of different categories of vehicle and the underlying trends in mobility. This paper uses UK national accident data and recently available exposure data to evaluate the developments of risk of fatal or serious injury in parallel with the risks of crash involvement

Injury patterns in side collisions - a new look with reference to current test methods and injury criteria

The UK in-depth data, describing the causation of injuries to casualties in side impacts, was examined for crashes occurring between 1992 and 1998. Slightly more casualties died in side impacts than in frontal crashes, and one third were seated on the side away from the collision. The collision severity was compared with the European and US legal test procedures and most MAIS 3+ survivors were observed to be in crashes above the severity of the test. The mean delta-V for the fatal group was 48 km/h compared with typically 25 km/h in the test. The most commonly injured body regions of both survivors and fatalities were the head, thorax and lower extremity. The lower extremity was the most frequent site of AIS 2+ injuries of survivors and fractures to the femur and tibia were highlighted, these injuries are not assessed by existing dummies

Powered two-wheeler crash scenario development

Powered two wheeler (PTW) riders are a group of vulnerable road users that are over represented compared to other road user groups with regards to crash injury outcomes. The understanding of the dynamics that occur before a crash benefits in providing suitable countermeasures for said crashes. A clearer interpretation of which factors interact to cause collisions allows an understanding of the mechanisms that produce higher risk in specific situations in the roadway. Real world in-depth crash data provides detailed data which includes human, vehicular and environmental factors collected on site for crash analysis purposes. This study used macroscopic on-scene crash data collected in the UK between the years 2000 – 2010 as part of the “Road Accident In-depth Study” to analyse the factors that were prevalent in 428 powered two-wheeler crashes. A descriptive analysis and latent class cluster analysis was performed to identify the interaction between different crash factors and develop PTW scenarios based on this analysis. The PTW rider was identified as the prime contributor in 36% of the multiple vehicle crashes. Results identified seven specific scenarios, the main types of which identified two particular ‘looked but failed to see’ crashes and two types of single vehicle PTW crashes. In cases where the PTW lost control diagnosis failures were more common, for road users other than the PTW rider detection issues were of particular relevance

The accuracy of CRASH3 for calculating collision severity in modern European cars

CRASH3 is a computer program that enables a vehicle's change of velocity during a crash to be deduced from the observed damage to the vehicle(s) involved. Along with other programs that share similar mathematical techniques, it is widely used internationally, particularly by groups and individuals who have access to damaged vehicles but not the accident scene, and it is applied to a wide range of vehicles and accident circumstances. Crash tests conducted under controlled conditions provide an opportunity to assess the program's accuracy. In this paper CRASH3 is applied to vehicles tested during 1996-98 in the first three phases of the EuroNCAP program. This includes results from 26 models tested in 64 km/h offset frontal impacts and 50 km/h side impacts. On average, velocity changes were underestimated by 1 km/h for the side test and 7 km/h for the frontal test–this includes the effect of a special treatment of deformable barriers not available in the standard program

Detecting deviation from normal driving using SHRP2 NDS data

Normal driving is naturally the first stage of the crash development sequence. Investigating normal driving can be proved useful for comparisons with safety critical scenarios and also crash prevention. The better we understand it, the more effectively we can detect deviations and stop them before they culminate in crashes. This study utilises Naturalistic driving data from the Strategic Highway Research Program 2 (SHRP2) to look into normal driving scenarios. Indicators’ thresholds were assumed with influence by the literature and then the values were validated based on real world data. The paper focuses on the methodology for deriving indicators representative of baseline, uneventful driving. With the approach that is presented here, reliable thresholds for variables can be introduced, capable of detecting the deviation on its very early onset

The statistical accuracy of Delta-V in systematic field accident studies

Much attention has been paid to the importance of calculating delta-V (the change of velocity during impact) and other impact severity measures accurately. However delta-V cannot be evaluated in every case sampled by a systematic study of road accidents. This can lead to statistical distortions if the subsample of cases for which delta-V is calculated is not representative of the whole sample. This problem has received less recognition than the problem of calculating delta-V accurately when it is calculated. This paper contains new results on the accuracy of CRASH3 delta-V for European passenger cars and a discussion of the problem of calculating delta-V for a representative subsample. On the data available, CRASH3 underestimates delta-V for rigid and deformable barrier impacts but not frontal car-to-car impacts. The statistical results obtained using any single method for calculating delta-V are likely to be unrepresentative of certain classes of impact type, impact severity and collision partner. A flexible approach towards using a variety of methods to evaluate delta-V is necessary to counter this difficulty

A statistical analysis of visual detection failures for active safety function evaluation

The objective of this study is to understand the visual detection failure sequences that result in traffic accidents. An accident causation analysis was used to interpret and group causal factors for 5 distinct detection failure types that caused traffic accidents. Principal component analysis was used to interpret in-depth, on spot, accident causation data. Several scenarios were identified describing combinations of context, contributory and precipitating accident risk factors. These scenarios are discussed with regards to the functionality active safety technologies and automotive systems designs with special emphasis on the driver’s needs, the safety functions needed to fulfil these needs and contextual constraints

Use of smart technologies to collect and retain crash information

Task 1.1 of Pendant Work Package 1 has a threefold objective: firstly to develop methods and guidelines for the reconstruction of road traffic accidents, secondly to develop a database of information about public domain crash tests, and thirdly to develop methods for determining the comparability and accuracy of reconstruction methods. As part of the third aim the Description of work (2001) states: "Specific reference will be made to the use of smart technologies to collect and retain information about the crash (‘black boxes’, ‘crash recorders’). The Task will examine current capabilities and identify the main obstacles to their wider implementation." The purpose of this report is to provide an overview of the state of the art in recording information about the crash phase, including current capabilities and main obstacles to further implementation

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 ultimate 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 airbags and better 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 driver injury risk in frontal crashes showed substantial reductions in injury risk for the head in newer cars. Risk of serious injury to the chest, thigh and leg showed little change between older and newer vehicles despite controlling for occupant parameters

The influence of European air bags on crash injury outcomes

The UK Co-operative Crash Injury Study currently includes data on 205 seat belted drivers from frontal impacts in which an air bag deployed; of these, 142 suffered some degree of injury. To detect the influence of frontal air bags, the distribution of injury over the body regions of these drivers was compared to that of a much larger group from vehicles without air bags. The injured drivers from air bag vehicles showed relatively fewer head injuries, especially fractures, and relatively more arm injuries. No abnormal types of injury or circumstances of injury were identified for the air bag group. Air bags generally appear to deploy at vehicle impact severities that pose a statistical risk of significant head injury, and also in a proportion of lower severity impacts. As a group, the air bag equipped vehicles were larger, more modern, and more often fitted with seat belt pretensioners than the non air bag vehicles, with an older and more male driving population