Robert Thomson

STRUCTURAL ADAPTIVITY FOR ACCELERATION LEVEL REDUCTION IN PASSENGER CAR FRONTAL COLLISIONS

A mathematical model was developed to explore and demonstrate the injury reducing potential of an adaptable frontal stiffness system for full frontal collisions. The model was validated by means of crash tests and was found to predict the peak accelerations of the crash test vehicles well, whereas correlation concerning mean acceleration or residual crush was not found. Vehicles were divided into three mass classes, and a test matrix was established in order to evaluate different combinations of vehicles involved in frontal crash at three closing velocities. In a baseline simulation setup, constant stiffness values were used and the results were compared to the corresponding simulations using adaptable frontal stiffness. Results show promising acceleration peak reductions at low speeds, implying that injury risk reductions are possible.

Study of heavy truck accidents with focus on manoeuvres causing loss of control

An analysis of heavy truck accidents based on the Large Truck Crash Causation Study database with respect to loss of control is presented. Heavy truck accidents were analysed with regard to the accident type, loss of control type, critical manoeuvre, vehicle combination type and different road characteristics. Three critical manoeuvres were identified as the most common manoeuvres causing loss of control. Based on the accident analysis results, relevant existing test manoeuvres were adapted for trucks and compared to determine a suitable test for evaluation of yaw stability of heavy trucks on a dry and level road. The comparison was conducted on a 5DOF tractor-trailer model in Matlab-Simulink.

A methodology to assess frontal stiffness to improve crash compatibility

Abstract Improved crash compatibility for vehicles is the next step towards increased frontal impact protection. Two aspects of crash compatibility are frontal stiffness and mass. Currently, frontal stiffness is related to mass and heavier vehicle tend to be stiffer than lighter ones. Consequently, the risk of being over-crushed in frontal impacts increases with mass-ratio. This study investigates one methodology to match frontal stiffness levels for vehicles in frontal impacts with different mass ratios. A generic, full vehicle multi-body model is used, the frontal stiffness properties of which are obtained from one full width crash test and one offset crash test. A small vehicle fleet has been developed using this methodology. The study shows one possibility for developing generic vehicle models that can be used to match frontal stiffness levels for vehicle with different masses.

Using Naturalistic Field Operational Test Data to Identify Horizontal Curves

Investigations to identify relationships between crashes and road features usually deal with effects of only one or two of the main components of traffic safety, i.e., human, vehicle, and infrastructure performance. There are several contributing factors of the components that together lead to a crash. This study devises an approach to include information from all three components in a system using field operational test (FOT) data. FOT data are recorded from real-life driving that is different from traffic simulations and specific on-site data collection. The study focuses on identifying horizontal curves using FOT and provides access to vehicle and human response data at the exact time when the vehicle drove in a specific location. A method has been developed to derive path radius and to identify start-end points of horizontal curves using FOT data. With this information, vehicle response signals and human behavior data can then be arranged on a common axis referenced to the curve. The approach also identifies lane changing maneuvers on curves that can be used to evaluate potential crash triggers. The application of this method allows for reviewing changes in the regulatory speed limit, curve geometry, or crash history and thus evaluates the design of curves and choosing appropriate countermeasures.

Single-Vehicle Collisions in Europe: Analysis Using Real-World and Crash-Test Data

Many European road casualties result from vehicles leaving the road, often impacting roadside obstacles. As part of the European Commission-funded project RISER (Roadside Infrastructure for Safer European Roads), several activities were undertaken to collate the type of real world crash data which is needed to understand single vehicle crash situations and relate this to crash-test data mandated in the European Union. Accident data were collected and used to create databases exclusively for single-vehicle collisions on major rural roads, simulation software was used to further understand impacts with roadside structures, and an inventory of crash-test data was collected for impacts with poles and safety barriers. The combination of accident data, simulations and crash-test data has provided a unique insight into the characteristics of single-vehicle collisions, helping those involved in the design and evaluation of the roadside environment to understand them better and make recommendations for consideration when drafting design guidelines.

Compatibility between passenger vehicles and road barriers during oblique collisions

Abstract In the European and US testing procedures for road barriers, vehicles are specified for the tests essentially by their mass properties. However, vehicles with similar mass can behave quite differently during a crash event. For the specific crash situation with the roadside restraint systems, e.g. W-beam guardrail, cable barriers, etc., the vehicle structure has to be compatible with the road restraint systems in geometry and crash stiffness to ensure safe operation during the interactions of vehicles and road barriers. The goal of this paper is to make a parametric investigation for the geometric compatibility between the compact passenger vehicles and the road barriers. The Finite Element model Ford Festiva and a weak-post W-beam guardrail were used for analyzing the oblique impact situation with a high impact speed and a small angle. For this specific situation the dynamic responses of the vehicle and the guardrail during impacts were investigated to study their structural interactions. The simulation results of the modified vehicle model and guardrail model were reasonable in comparison with the crash test data under the similar impact conditions.

Proposal for a frontal impact and compatibility assessment approach based on the European FIMCAR Project

Objective: To improve vehicle safety in frontal collisions, the crash compatibility between the colliding vehicles is crucial. Compatibility aims to improve both the self and partner protection properties of vehicles. Although compatibility has received worldwide attention for many years, no final assessment approach has been defined. Methods: Within the Frontal Impact and Compatibility Assessment Research (FIMCAR) project, different frontal impact test procedures (offset deformable barrier [ODB] test as currently used for Economic Commission for Europe [ECE] R94, progressive deformable barrier test as proposed by France for a new ECE regulation, moveable deformable barrier test as discussed worldwide, full-width rigid barrier test as used in Federal Motor Vehicle Safety Standard [FMVSS] 208, and full-width deformable barrier test) were analyzed regarding their potential for future frontal impact legislation. The research activities focused on car-to-car frontal impact accidents based on accident investigations involving newer cars. Test procedures were developed with both a crash test program and numerical simulations. Results: The proposal from FIMCAR is to use a full-width test procedure with a deformable element and compatibility metrics in combination with the current offset test as a frontal impact assessment approach that also addresses compatibility. Conclusions: By adding a full-width test to the current ODB test it is possible to better address the issues of structural misalignment and injuries resulting from high acceleration accidents as observed in the current fleet. The estimated benefit ranges from a 5 to 12 percent reduction of fatalities and serious injuries resulting from frontal impact accidents. By using a deformable element in the full-width test, the test conditions are more representative of real-world situations with respect to acceleration pulse, restraint system triggering time, and deformation pattern of the front structure. The test results are therefore expected to better represent real-world performance of the tested car. Furthermore, the assessment of the structural alignment is more robust than in the rigid wall test. Supplemental materials are available for this article. Go to the publishers online edition of Traffic Injury Prevention to view the supplemental file.

Car-Car Crash Compatibility: Development of Crash Test Procedures in the VC-Compat Project

Abstract A major component of the EU Fifth Framework Programme sponsored project “Improvement of Vehicle Crash Compatibility Through the Development of CrashTest Procedures” (VC-Compat) focused on car-to-car frontal crash compatibility. The work program was composed of four main activities, a structural survey, cost-benefit analyses, crash testing, and supporting modeling work. All these activities focused on the development of two candidate test procedures, namely the full-width deformable barrier (FWDB) and progressive deformable barrier (PDB), which are capable of assessing a cars structural interaction potential. These tests have different approaches; the FWDB assessment is based on load cell wall force measurements, whereas the PDB assessment is based on deformation measurements. This work supports the activities of the European Enhanced Vehicle Safety Committee working group on frontal impact and compatibility, which has the task to propose draft test procedures to assess a vehicles crash compatibility in 2007.

Assessment of the impact speed and angle conditions for the EN1317 barrier tests

ABSTRACT Roadside safety barriers designs are tested with passenger cars in Europe using standard EN1317 in which the impact angle for normal, high and very high containment level tests is 20°. In comparison to EN1317, the US standard MASH has higher impact angles for cars and pickups (25°) and different vehicle masses. Studies in Europe (RISER) and the US have shown values for the 90th percentile impact angle of 30°–34°. Thus, the limited evidence available suggests that the 20° angle applied in EN 1317 may be too low. The first goal of this paper is to use the US NCHRP database (Project NCHRP 17–22) to assess the distribution of impact angle and collision speed in recent ROR accidents. Second, based on the findings of the statistical analysis and on analysis of impact angles and speeds in the literature, an LS-DYNA finite element analysis was carried out to evaluate the normal containment level of concrete barriers in non-standard collisions. The FE model was validated against a crash test of a portable concrete barrier carried out at the UK Transport Research Laboratory (TRL). The accident data analysis for run-off road accidents indicates that a substantial proportion of accidents have an impact angle in excess of 20°. The baseline LS-DYNA model showed good comparison with experimental acceleration severity index (ASI) data and the parametric analysis indicates a very significant influence of impact angle on ASI. Accordingly, a review of European run-off road accidents and the configuration of EN 1317 should be performed.

Development of compatibility assessments for full-width and offset frontal impact test procedures in FIMCAR

The goal of the project FIMCAR (Frontal Impact and Compatibility Assessment Research) was to define an integrated set of test procedures and associated metrics to assess a vehicles frontal impact protection, which includes self- and partner-protection. For the development of the set, two different full-width tests (full-width deformable barrier [FWDB] test, full-width rigid barrier test) and three different offset tests (offset deformable barrier [ODB] test, progressive deformable barrier [PDB] test, moveable deformable barrier with the PDB barrier face [MPDB] test) have been investigated. Different compatibility assessment procedures were analysed and metrics for assessing structural interaction (structural alignment, vertical and horizontal load spreading) as well as several promising metrics for the PDB/MPDB barrier were developed. The final assessment approach consists of a combination of the most suitable full-width and offset tests. For the full-width test (FWDB), a metric was developed to address structural alignment based on load cell wall information in the first 40 ms of the test. For the offset test (ODB), the existing ECE R94 was chosen. Within the paper, an overview of the final assessment approach for the frontal impact test procedures and their development is given.