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http://www2.dft.gov.uk/transportforyou/ ... ge=3#a1002""
executive summary:
The safety of wheelchair occupants in road passenger vehicles
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Executive summary
Over recent years a number of legislative tools and codes of practice have been put in place to provide wheelchair users with greater access and freedom of use of public transport. Such regulations range from guidelines issued by national Governments, with the UK Government taking a lead role, to full EC directives. While these positive steps have achieved the aim of providing a greater choice and freedom of transport use to wheelchair users, the issue of safety in the event of an accident has not been rigorously assessed in a consistent manner across the various categories of road vehicles available to this group of travellers.
This project, commissioned by the UK Department for Transport, aimed to address the safety of adult wheelchair users in M1, M2 and M3 vehicles, i.e. private vehicles, taxis, minibuses, coaches and urban buses. The objective was to make recommendations for requirements on these categories of vehicles that would provide wheelchair users with at least an equivalent level of protection as a passenger seated in a conventional seat (fitted with a headrest) in the event of an accident. In addition, the security of carriage of a wheelchair user in an urban bus under normal operating conditions was also investigated.
The project tackled these issues firstly through a programme of numerical simulation, validated against a limited number of physical tests, the results of which helped to define a wide ranging testing programme. Initial work reviewing suitable test conditions indicated that the scope of vehicles could be addressed by examining 4 sets of conditions:
Forward facing wheelchair users in M1 or M2 category vehicles
Rearward facing wheelchair users in M1 or M2 category vehicles
Forward facing wheelchair users in M3 category vehicles
Rearward facing wheelchair users in M3 category vehicles
The protection provided for passengers was tested using conventional automotive crash test dummies, and the risk of injury assessed using the usual injury criteria derived from the dummy outputs. In each case a conventionally seated passenger configuration was tested to determine a comparable level of protection for the wheelchair seated occupant.
M1 and M2 vehicles were able to be considered together as previous research has shown that the same deceleration pulse is appropriate for the majority of both categories.
The modelling work indicated that the most influential parameters on the safety of wheelchair passengers are the location of the diagonal belt upper anchorage (i.e. upper location or floor level), the presence or otherwise of a head and back restraint and the closeness of fit between the wheelchair and the head and back restraint if fitted.
For forward facing occupants in M1 and M2 category vehicles it was apparent that some injury criteria such as head displacement and lumber spine compression were better for the wheelchair occupant than the conventionally seated occupant, however neck loads in particular were higher. The addition of a head and back restraint was found to improve the situation significantly, although the presence of a gap between the head and back restraint and the wheelchair had a detrimental effect. Any such head and back restraint should be compliant with the strength and energy absorption requirements of ECE Regulation 17. In general, an upper anchorage was preferable to a floor mounted anchorage.
Rear facing wheelchair passengers in M1 and M2 vehicles were found to be greatly more at risk than equivalent vehicle seated passengers, particularly in terms of neck and spine loads, the situation being worse still for both smaller and larger than average persons. Again, the situation was mitigated through use of a head and back restraint compliant with ECE Regulation 17, assuming a minimal gap between the wheelchair and the head and back restraint and a minimum horizontal strength requirement of 100kN.
The situation for forward facing passengers in M3 vehicles was similar to that for M1 and M2 vehicles, and the findings were also similar in that a head and back restraint was of benefit (compliant with ECE Regulation 17) with no gap and an upper belt anchorage.
Rear facing wheelchair passengers in M3 vehicles fitted with a back restraint not intended to provide crash protection, were found to be subject to unacceptably high head accelerations. The use of a head and back restraint compliant with Regulation 17 resolved the issue.
In all cases the anchorage loads were recorded and recommendations made for requirements on the anchorage strength in vehicles of each category. Likewise, occupant space requirements were derived from the dummy excursions for forward facing occupants.
The normal transit tests revealed that a vertical stanchion provides a better restraint on excessive wheelchair movement than does a horizontal bar. However, the tests only used a single type of wheelchair and hence any conclusions should consider the potential interaction of these systems with other wheelchair types.
The findings from this work have been developed into a set of recommendations for each category of vehicle which may form the basis for changes to regulations at the discretion of DfT.
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Best,
Martin