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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - SENIORS (Safety-ENhancing Innovations for Older Road userS)

Teaser

Summary

In an ageing society, SENIORS improved the safe mobility of the elderly, and overweight. The project primarily investigated and assessed the injury reduction achievable through innovative and suitable test methods as well as passive vehicle safety systems targeting the protection of the elderly as pedestrians or cyclists (ERU) and car occupants involved in vehicle impacts. Short- to mid-term effects on elderly road userâ€™s safety are expected, also by transferring the younger generationsâ€™ safety benefits, with the following objectives achieved:

1) Improve the protection of elderly road users
2) Understand the influence of age in pre-crash and crash occupant dynamics
3) Understand the anthropometry and injury mechanisms of elderly and overweight people
4) Develop and optimise test tools, procedures and assessment methods
5) Transfer knowledge and results to interested experts, regulatory bodies, consumer entities etc.

What next?
- Tests with ATDs are still required. However, HBMs offer great potential for traffic safety increase. Simulations offer a possibility to cover a wider range of injury causing collision scenarios
- Additional PMHS and volunteer tests are required to enhance HBM developments and to update injury risk curves. ATDs will also benefit
- SENIORS has facilitated this by making a well-defined and well-documented test environment publically available (Generic Test Rig)
- Restraint loads should be lowered whenever feasible; leading to a benefit for everybody, and definitely for older persons
- In future experimental testing will partly be replaced / added by simulations

SENIORS showed that Passive Vehicle Safety is indispensable and still has a high safety potential, but the knowledge about crashes and biomechanics needs further enhancement!

Work performed

By the analysis of collision and hospital databases thorax injuries to older car occupants and head, thorax and leg injuries to ERU were identified as the priorities for prevention.

Occupant
A novel simulation-based method for developing injury risk functions (IRF) used HBM and ATD models rather than PMHS testing. The THUMS TUC HBM was updated to represent both 35 and 65+ year-old people, including changes to the shape of the rib cage, the thickness of the ribs and the strength/elasticity of the bone and cartilage. These updates are available to other researchers. The GHBM model was also investigated.
A novel â€˜generic sled rigâ€™ was developed and used in tests with volunteers, PMHS and ATDs. It is a repeatable and reproducible well-defined set-up, representing the loading conditions of a contemporary vehicle.
Further, sled tests with the THOR ATD and the Elderly, Overweight Dummy (EATD) were conducted with adaptive restraints and concepts like four-point or split buckle belt systems distributing the loading on the chest. These tests showed clearly the benefit of advanced restraints concepts, the advantages of the THOR and multi-point thoracic injury criteria.
SENIORS developed IRF specific to the 65+ year-old occupant.
The EATD addresses the trend of overweight and is closer to the real anthropometry of older people and can be exploited as a long term test tool for consumer or regulation use after going through revisions to improve its biofidelity, durability and repeatability.
Younger and older volunteers were also tested in simulators and real vehicles to measure their kinematics and EMG muscle responses to emergency manoeuvres. Major findings were implemented in an Active HBM.

ERU
An upper body mass (UBM) has been connected to the FlexPLI impactor with a flexible rubber element aiming to better address pedestrian femur injuries, high frontend geometries and angled surfaces at the end of the bumper test area. Validations against the THUMS v4 have led to a tool more humanlike in its kinematics. Simulation and hardware and their test results will be made available for industry awareness to fully evaluate its performance.
The Thorax Injury Prediction Tool (TIPT) is a completely new test tool for pedestrian / cyclist protection to address thoracic injuries (rib fractures) for the first time. Virtual tests were conducted using HBMs and a thoracic impactor to assess its reliability, robustness and reproducibility. After prototyping, its feasibility of a component test was investigated.
A combined test and assessment procedure is proposed covering the demands of pedestrians and cyclists in collisions with passenger cars. The assessment procedure for VRU Box 3 of Euro NCAP was revised.

Dissemination and Exploitation
All the technical knowledge gained is reported in deliverables but also presented at conferences. As further examples, the generic test rig, sled test results and the knowledge about the age-modified HBM will be transferred to others (e.g. projects OSCCAR and VIRTUAL). In addition, the proposed test and assessment methods regarding moderate-speed frontal impact tests and a combined test procedure for pedestrians and cyclists as well as the FlexPLI-UBM will be presented to Euro NCAP. SENIORS partners will also report to regulatory bodies and Standardization Organisations.

Final results

Older occupants are at greater risk of serious/fatal injury than younger. These injuries (especially to the thorax) often occur at moderate collision severities, e.g. 30-40 km/h frontal impacts. This demonstrates that improvements to vehicle crash structures and restraint systems, which have delivered large benefits for younger occupants, have been less effective for older occupants.

Previous PMHS data is mainly high-severity tests with concentrated belt force, more like cars from 20 years ago. SENIORS developed a â€˜generic sled rigâ€™ to load PMHS, ATD and HBM the way modern cars do, with moderate belt forces and airbags. The designs for all aspects of the rig are publically available, including CAD and FE models.

Several new restraint system concepts were tested in frontal impacts and gave very large reductions in injury risk for older occupants. New test and assessment procedures were developed to encourage implementation of these restraints. Implemented in all new EU cars from 2020, these novel belts could save 800-1,200 lives and 6,500-10,500 serious injuries over ten years, or 4.7-8.1 billion Euros.

SENIORS extended ERU head impact test zones to include a greater proportion of cyclist head impact locations and adjusted the impact conditions to represent both pedestrians and cyclists. The effect of ADAS sensors mounted to the windscreen can also be assessed.

ERU thorax injuries were addressed by the TIPT which would benefit ERU impacted by the bonnet of a vehicle, and give a more informative and biofidelic way of testing the risk of vehicles with high bonnet leading edges, such as large SUVs and pickups, but also for new classes of vehicle for which aerodynamics is not a priority, such as last-mile shuttles. Further research is required to specify the most appropriate tool.

The FlexPLI-UBM shows important advantages over the standard FlexPLI used in UN regulations and Euro NCAP by:
- Improved kinematics of impact allowing more biofidelic assessment of knee and tibia injury risk, and the assessment of femur injury risk in the same tool.
- Enabling more appropriate testing near the end of the bumper beam, where modern cars often have an angled profile and by eliminating unrealistic rotation of the standard tool.
- Vehicles with very high front-end geometries can be tested and assessed.