The policy context of the SAFEINTERIORS project stems from both European and National initiatives. European standards and legislative documents define 'crashworthiness' standards and technical specifications for interoperability. National actions complete these European initiatives; standards set in the United Kingdom (Association of Train Operating Companies), specifications established in France, the setting up of a German dedicated group to train safety, etc.
Train crash events can be basically divided into two phases:
- the primary collision, where the initial kinetic energy is progressively dissipated by means of plastic structural deformation. In this phase, occupant compartment integrity and acceptable vehicle acceleration levels (crash pulses) are the most important design requirements to be considered;
- the secondary collision, where the occupant will be subject to a great variety of potentially harmful occupant/interior or occupant/occupant contacts.
This new interior passive safety framework will provide a systems approach to drastically reduce injuries and fatalities by combining and exploiting - in a cost-efficient and optimised manner - the already well-matured railway structural crashworthiness (closely linked with primary collision events) with injury biomechanics that are directly associated with secondary collisions.
There is still an ongoing major effort, to identify, formulate and implement proper solutions for safety issues in guided transportation systems. These include, in general:
- collision avoidance, where the main objective is to develop active safety systems to prevent accident occurrence;
- accident survivability involving passive safety requirements for structural crashworthiness;
- vehicle-interior solutions that contribute to the reduction of the occupants injuries' severity.
SAFEINTERIORS aimed to provide a structure to implement a full methodology to design, test and validate improved interior solutions for passenger trains, thus reducing the levels of fatalities and injuries in rail accidents. The purpose of the interior passive safety developments is to provide the different railway stakeholders with a framework capable of assessing interoperability of all present and future interior rail vehicle layouts. It is designed to assess new interior solutions following advanced requirements covering, in a systematic manner, representative layouts, a range of suitable crash pulses and new test and validation procedures suitable to the rail industry.
Therefore, to improve the chances of survival in catastrophic events, the SAFEINTERIORS project:
- appraises requirements and validation procedures in order to propose best practices for future standards, recommendations and regulations;
- explores the suitability of proposed interior passive safety methodologies as applied in the retrofitting of existing rail vehicles, thus contributing to speeding up the introduction of improved passive safety levels in the railway sector;
- designs, builds and tests novel vehicle interiors for train drivers and passengers - including the design of 'friendly' compartment interiors;
- incorporates advanced ergonomics and new safety features that provide occupants with the best possible working and travelling conditions;
- provides interoperability, since the designs and corresponding specifications are meant to be adopted across Europe, so that future rail vehicle interiors will all have harmonised safety levels and will function across national borders.
The project can be broken down as follows:
- A review of the current design practices and assessment of conclusions of previous projects relevant to passive safety of train interiors, taking into account the compatibility with other relevant regulations. An analysis of existing accident data is also undertaken, including the selection of the crash pulses required to analyse the rail vehicle interiors isolated from the structures and structural devices for energy management during the crash.
- This step identifies the relevant injury criteria for different body parts of the rail vehicle occupant, taking into account the selected crash scenarios and the interior layout of rail vehicles. It also identifies measuring devices to quantify injury for the body parts relevant to rail occupant analysis and defines relevant test procedures that can be used during the interior design and during interior passive safety validation of solutions.
- Operational and commercial requirements are identified in order to define the most relevant interior features and define requirements for the interior layouts, including seats, bulkheads and other relevant interior equipment. An assessment of the potential use of emerging technologies and new materials is also undertaken. These measure are aimed at developing new design solutions and manufacturing test layers to be tested and validated.
- Four to five different scenarios based on passenger positions (bay seating, row seating, lateral seating, longitudinal seating, standing passengers, wheelchair restraint) are developed, manufactured, tested and validated. These lead to new component designs improving the enhancement of occupant interior passive safety levels. Other objectives are to assess the suitability of the new component design requirements, to appraise the introduction of new test methods, measuring devices and injury criteria.
- This last step compiles the main results and presents the overall conclusions and conducts a critical appraisal of the followed methodology, injury criteria, measuring and testing procedures. A final assessment of new design requirements and suitability for implementation is also carried out. Lastly, as well as providing the technical background and recommendations for the feasibility of new passive safety interior solutions, a technical framework for the production of a European norm is also provided, as well as a relevant TSI chapter to be issued as a complement to the structural crashworthiness norm.
The work performed by SAFEINTERIORS has produced very interesting results that can be grouped into the following outcomes:
- An accident database and structure providing a methodology for standardisation of post-accident injury data collection;
- A tool kit including a defined set of injury criteria with limits, test devices, and test methods, to assess potential occupant injury levels in all foreseeable rail applications;
- A family of validated models for the representative vehicle interior layouts as well as a process for passive safety design and validation of such interior layouts.
The results of SAFEINTERIORS have been processed with a focus on delivering valid and viable recommendations.
The SAFEINTERIORS findings show that transverse seating and fixed tables are the main components for providing occupant containment, therefore optimising their characteristics is the most effective approach for reducing injury severity.
It would seem that there are existing test devices available to measure all of the recommended injury criteria. The direct consequence of this is that no new devices or development of existing devices are needed, and there will be no device development and efforts should be allocated to critique the available devices and develop the testing methodologies for rail applications. For some injury criteria a number of test devices are available to measure them, and it will be necessary to decide which tools are the most appropriate.