HARNESS ATTACHMENT POINT TESTING USING AN ARTICULATED, INSTRUMENTED DUMMY

Transcription

1 HARNESS ATTACHMENT POINT TESTING USING AN ARTICULATED, INSTRUMENTED DUMMY Test carried out by RTA Crashlab, Australia, 2002 Presentation by Peter Ferguson, First Access ISFP Symposium, Las Vegas, June

2 WHAT WAS THE NEED? Harness design was focussed on arresting a fall and NOT on working in harness mandatory rear high attachment point Concerns about POST fall management of casualty, particularly in relation to suspension trauma/intolerance No criteria set in Australian / New Zealand Standard for ergonomic approach to harness design and use 3 HISTORY Harness use had been evolving with increasing focus on: USING harness as a working tool instead of simply something to arrest the fall Concerns about how a fallen worker could self manage to effect a rescue or assist in a rescue 4 2

3 SUSPENSION TRAUMA/INTOLERANCE Concerns that if suspended from rear, the possibility of suspension trauma/intolerance is much higher This condition is NOT caused by a harness or being suspended in a harness It is caused by being vertical and being immobile A tight or poorly adjusted harness may exacerbate the condition but not cause it 5 DORSAL ATTACHMENT After the fall, you are limited what you can do to self rescue or self manage when connected from rear (dorsal) position 6 3

4 HOW MAY HARNESS ATTACHMENT POSITION ASSIST? It was felt, based on rescue training and rope access experience, that a front attachment would allow the casualty, post fall, to use arms and legs to self rescue or participate/assist in rescue Also felt that if the casualty is left hanging, they have some chance of adjusting position, raising knees, performing muscle pumping exercises etc to delay the onset of suspension trauma / intolerance 7 WHY TEST? There had a been a long held perception that a person falling and being arrested by rear high attachment point would experience the least impact, rotation etc and as such, would be safest with a rear attachment This perception had been based on previous testing that: Often tested feet first fall When testing head first fall, the dummy lacked the head, arms and legs to demonstrate what would really happen in the fall The testing had all been carried out using a non articulated timber body block 8 4

5 WHY TEST CONT D There was a growing concern world wide that testing with a non articulated body block was ONLY a way of testing the strength of the harness and did very little to replicate the real life effects on a person s body As such, while useful as a Standards compliance test for strength only, the use of the body block should not be used in the future as a development tool or even a tool to fully prove compliance 9 BODY BLOCK USED IN STDS TESTS 10 5

6 HOW DID TESTING COME ABOUT? Concerns as set out in previous slides ISO meeting in Sydney allowed a meeting of international experts to be set up to consider how the upcoming re-write of Australian / New Zealand Standard may approach issues Due to international involvement, a European manufacturer offered to supply harnesses for test 11 HOW DID TESTING COME ABOUT? CONT D Funding was obtained from WorkCover NSW, one of the Australian Regulatory bodies We were able to obtain the use of a Federal Government THOR crash test dummy, usually used for vehicle crash testing We were able to secure the services of a Biomechanical expert (Tom Gibson, Human Impact Engineering, Sydney NSW) to allow proper analysis of the results to see what results were likely to be sustained without injury 12 6

7 WHICH ORIENTATIONS WERE TESTED? High rear (Dorsal attachment) High front (Sternal attachment) Low front (waist) Low rear (waist) for interest no suggestion this should be used in the field! Feet first Head first Some tests were carried out using an energy absorber but most were without (for expediency) 13 THOR DUMMY 14 7

8 AREAS OF BODY ANALYSED Head acceleration (x, y & z directions) Upper neck loads (Fx, Fy, Fz, Mx, My & Mz) Chest acceleration (In the x, y & z directions) Upper and lower abdominal displacement, and Pelvis acceleration (in the x, y & z directions) 15 RAPID CHANGE OF DIRECTION = WHIPLASH? A SKETCH FROM THE TEST REPORT Imagine the acceleration on the neck when the body stops falling and must suddenly rotate 180 degrees. 16 8

9 CURRENT STANDARDS COMPLIANCE TESTING head up head down Note there is no head, arms, legs or flexible torso to affect the results the results are almost exclusively about loads 17 RANGE OF TESTING UNDERTAKEN 30 DROPS TOTAL 18 9

10 BROAD RESULTS Analysis based upon outcomes that should not cause injury, not just survivability Acceptable injury criteria derived mainly from automotive industry norms but with some cadaver testing as well for head injury data Most testing done without the use of an energy absorber, but with 2m drop (against 3.8m possible fall in the field) as such, impact forces likely to be higher than in field but durations possibly shorter than in field 19 WHAT WAS FOUND? Head strike from rear or front attachment was a factor did not instrument to verify if this would be enough to cause injury The video results highlight the possibility / likelihood of head injury from contact with structure The body area that showed up as the most marginal (and at times above injury level) was the neck Thus, head and neck injuries appear to be where additional works should be undertaken 20 10

11 THE BOTTOM LINE NECK IS THE LIMITING FACTOR (SEE LH COL) 21 COMPARISON TEST, REAR ATTACHMENT, HEAD DOWN FALL (WATCH THE NECK EXCEEDED INJURY LEVEL!) 22 11

12 REAR ATTACHMENT, FEET FIRST NECK BELOW INJURY LEVEL 23 FRONT ATTACHMENT, FEET FIRST NECK BELOW INJURY LEVEL 24 12

13 REAR ATTACHMENT, HEAD FIRST (NECK LOADS EXCEEDED INJURY THRESHOLD) 25 FRONT ATTACHMENT, HEAD FIRST (NECK EXCEEDED INJURY THRESHOLD) 26 13

14 FURTHER WORK REQUIRED? The testing and report set out to answer a specific question are we (the committee writing the Australian/New Zealand Standard for harnesses) justified to move to a front attachment point? This point seemed well proven (though with issues neck injury potential) The report raises some questions however, especially in relation to head and neck injury & especially in HEAD FIRST falls 27 FURTHER WORK REQUIRED? More work needs to be done in this area as does the BIG dual issues of a/minimising fall distance, and b/minimising injury (and equipment damage) from the structure This is not simply a technology (product) area but also one relating to how equipment is USED 28 14

15 FURTHER WORKS CONT D Look at innovative and different designs of equipment, eg Harness design from Australia with a lying back post fall suspension AND neck support during and after fall (SAS Harness) UK design that does not have crutch straps (ZT Safety Harness) Lanyards that may be more resistant to edge damage Japanese invention that deploys air bags around user Etc Consider adding more ergonomic requirements (once we work out what they should be!) to Standards 29 ERGONOMICS? An important reminder of the need for Good harness design Short fall / low energy arrest force But especially Correct adjustment of the harness in use! 30 15

16 UK ZT HARNESS NOT ASSERTING THIS IS GOOD OR BAD, JUST THAT IT IS A NEW APPROACH No crutch straps is this a feature for future harnesses? ZT harness note no crutch straps Common harness 31 AUSTRALIAN SAS HARNESS Features include reclining position post fall Neck support at rear during and after fall Are these ideas we should consider in the future? 32 16

17 THE FUTURE If these features, (SAS harness and those of ZT harness) are worth considering, do we need extra testing and do we need to change requirements of Standards? Ie. criteria One thing is certain the need for an articulated and instrumented test dummy is CRITICAL for development works and probably also for Standards compliance works this was shown by the testing Additionally, far more requirements in Standards are in order to consider ergonomics Also, the issue of head and neck injury needs to be considered 33 WEAR A HELMET, AND USE ONE WITH 4 STRAP FIXING! Video care of SUVA Switzerland 34 17

18 HELMETS WATCH THE HEAD ON THE SCAFFOLD! 35 Video from SUVA Switzerland HELMET WATCH THE: ROPE OVER EDGE, AND HEAD UNDER ROOF 36 18

19 AGAIN, CAREFUL WHAT YOUR HEAD MAY HIT! 37 Video SUVA Switzerland LANYARD BREAKS OVER EDGES (NOTE TEST HAS NO ENERGY ABSORBER) 38 Video SUVA Switzerland 19

20 WHAT CAN BE DONE NOW? Don t fall if works are done without harness use, in situations where a fall is not possible, then all the issues disappear! Use harness to work not fall if harness use is unavoidable, then use better (user adjustable) equipment and better (training and supervision) users so a fall is less likely AND a rescue can be effected quickly 39 WHAT CAN BE DONE NOW? PROTECT YOUR HEAD! Helmets it s very clear that head injury is a BIG risk. Requiring use of a helmet rated for falls (fastening method and impact resistance) is a MUST 40 20

21 WHAT CAN BE DONE NOW CONT D (DON T FALL HEAD FIRST!!) Ropes over edges more thought needs to be given to the possibility of equipment damage and to personnel damage from structure in many cases, this may mean a harness solution is NOT appropriate Trial / test innovative new designs such as the UK non crutch strap harness and the new Australian product with neck support and different front attachment Move to the use of an articulated dummy for Standards tests and product manufacturing testing Use front attachments (sternal) for most harness use to assist with post fall management 41 Thanks for your attention, any questions? Peter Ferguson, peter@firstaccess.com.au, cell Please send me an with mailing address if copy of report and video is required a disk will be sent 42 21