RR406 Seatbelt Performance in Quarry Vehicle Incidents
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HSE Health & Safety Executive Seatbelt performance in quarry vehicle incidents Final Report Prepared by TRL Ltd for the Health and Safety Executive 2005 RESEARCH REPORT 406 HSE Health & Safety Executive Seatbelt performance in quarry vehicle incidents Final Report T Smith MEng (Hons) AMIMechE G Couper MEng MSc (Eng) W Donaldson MEng (Hons) AMIMechE Dr M Neale BEng(Hons) MSc PhD AMIMechE J Carroll BSc (Comb Hons) TRL Limited Crowthorne House Nine Mile Ride Wokingham Berkshire RG40 3GA Quarrying and open cast coal mining has been recognised as one of the most dangerous work environments in which to be employed, with the fatality rate more than three times that of the construction industry and 20 times that of all industry (Foster, 2003). The most frequent type of accident in quarries is those involving vehicles, accounting for approximately 40% (HSE, 1993). Industry standards have been implemented in the UK with respect to all round visibility from vehicles, edge protection and brake testing to reduce the number of casualties. The effectiveness of restraint systems is considered as the next step to achieving casualty reduction targets. This research has reviewed current international standards relating to occupant protection and accident data. A range of accident conditions were simulated using multi-body numerical models that were evaluated against data from full scale tests. This information was supplemented by assessing the risk from structures inside the vehicle cab and consideration of practical issues relating to the use of restraints. Restraint of the torso was shown to provide additional benefits over the current lap belts. Wider implementation of more comprehensive restraint systems should be encouraged. However, a number of issues should be considered before full implementation throughout the industry. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy. HSE BOOKS © Crown copyright 2005 First published 2005 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. Applications for reproduction should be made in writing to: Licensing Division, Her Majesty's Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to [email protected] ii CONTENTS Executive summary v 1 Introduction 1 2 Review of literature and standards 3 2.1 Analysis of the literature and standards 3 2.2 Conclusions 5 3 Accident analysis 7 3.1 Methods 7 3.2 Results 7 3.3 Discussion of the accident statistics 17 3.4 Conclusions 18 4 Physical testing 21 4.1 Methods 21 4.2 Results 25 4.3 Conclusions 29 5 Numerical simulation 31 5.1 Methodology 31 5.2 Results/Discussion 41 5.3 Conclusions 52 6 Occupant protection 55 6.1 Method 55 6.2 Vehicle inspection observations 56 6.3 Analysis and Discussion 66 6.4 Conclusions 71 7 Consideration of restraint systems effectiveness and acceptance 73 7.1 Restraint types 73 7.2 Vehicle types 74 7.3 Methodology 74 7.4 Literature review of restraint types and effectiveness 75 7.5 Consultation with industry 76 7.6 Discussion 81 7.7 Recommendations 84 7.8 Conclusions 85 8 Discussion 87 iii 9 Conclusions 89 10 Recommendations 91 Appendix A Review of literature and standards relating to seatbelts 93 A.1 Literature relating to occupant restraint in off road machinery 93 A.2 Regulations stating requirements for use of restraints in off-road work machines 94 A.3 International Standards for restraint systems 97 A.4 International standards relating to rollover protection (ROPS) 104 Appendix B Restraint specifications 111 Appendix C Numerical simulation - model evaluation 117 Appendix D Numerical simulation - results 121 Appendix E Literature review – effectiveness of restraints 129 Appendix F Acknowledgements and Contacts 135 References 137 Glossary 141 iv EXECUTIVE SUMMARY Quarrying and open cast coal mining has been recognised as one of the most dangerous work environments in which to be employed, with the fatality rate (number of fatalities as a percentage of employees) more than three times that of the construction industry and 20 times that of all industry (Foster, 2003). The Health and Safety Commission (HSC) and the Health and Safety Executive (HSE) are responsible for regulating risks to health and safety in UK work places. Part of the HSC Strategic Aim was to meet the quarry industries Hard Target initiative to reduce accidents by 50% between 2000 and 2005. The most frequent type of accident in quarries is those involving vehicles, accounting for approximately 40% (HSE, 1993). These types of accident can have a high risk of death, accounting for 60% of fatalities in the RIDDOR (RIDDOR 1995) database for 2000/2001. Accidents where earth-moving machinery is involved in an impact or rollover result in a substantial number of fatal and serious injuries worldwide. Industry standards have been implemented in the UK with respect to all round visibility from vehicles, edge protection and brake testing to reduce the number of casualties. The effectiveness of restraint systems is considered as the next step to achieving casualty reduction targets. The minimum requirements for restraints in such vehicles are two point lap seatbelts, which some accident investigations suggest may have contributed to the severity or cause of injuries. TRL Ltd were commissioned by the HSE to carry out an investigation of the effectiveness of occupant restraint systems in selected vehicle incidents in the quarrying industry. The objectives of this research were: • To review current standards and practices in the UK and overseas • To evaluate the performance of different restraint systems in different vehicle types and incident scenarios • To make recommendations as to the most effective restraint systems in order to minimise injury over a range of accident situations The current standards and practices for operator restraints were reviewed for both the UK and overseas. This confirmed that minimum requirements in most countries were to fit two point lap belts and the SAE Information Report J2292 provides technical guidance for upper torso restraints and the use of retractors. The Australian Standard AS 2664 also provides requirements for the anchorage points of a torso restraint (diagonal belt). The performance of different restraint systems, including lap belts, three-point lap-diagonal belts and harnesses, were assessed by numerical simulation. The numerical simulation was supported by accident analysis to determine the vehicle types and scenarios to be modelled. Four vehicle types were considered, rigid dump truck, articulated dump truck, wheel loader and dozer. All scenarios were simulated with a 50th percentile human body model and some cases were repeated with a 95th percentile human body model. One of the vehicle models was evaluated against data collected during full scale rollover tests. In general, improving the restraint of the torso reduced the risk of injury from contact with other items in the cab, however, a harness type restraint was more effective for both clockwise and anti-clockwise rollovers. Practical issues relating to the use of the different restraint systems was also considered which included acceptability by the vehicle operators. This included consultation with vehicle operators who had used both lap and harness type restraints. It was found that acceptance of a different type of restraint would be mainly dependent on the type of work being carried out. It is likely that most of these issues can be resolved through improved design of vehicles, seats and restraints but further, more objective, investigation of the issues will be required. v The assessment of the restraint systems was supplemented by a risk assessment of the interior of the cab which allowed items within the cab that could not be included in the models to be assessed. It was found that cab interior design was typically not occupant friendly and that hostile structures (e.g. small radius steel handles) were frequently located in areas that critical body regions such as the head are likely to collide with during a rollover or frontal collision. Improvement in occupant protection could be achieved through improved design (e.g. moving hostile structures or making them softer or less “sharp”) and ideally this would be combined with improved restraint to reduce the size of the envelope into which the head could move during a collision. This research has identified a potential issue with locking mechanisms used in the retractor on the lap belts tested, where during the slow speed rollover (falling under gravity over period of half a second) they did not lock. This should be further investigated to ensure that current lap belts are working effectively, maybe leading to alternative locking retractor designs. Restraint of the torso, particularly with a harness type restraint, has been shown to provide additional benefits over the current lap belts. It is recommended that wider implementation of more comprehensive restraint systems be encouraged in particular operating conditions. However, before full implementation throughout the industry there are a number of issues that need to be addressed. These include the lack of standards for the design of such systems for quarry vehicles, the potential increased risk of injury during normal operation and the range of movement required by vehicle operators to work efficiently and safely. It is also recommended that manufacturers should be encouraged to consider occupant protection when designing cab interiors. Measures should include considering positioning of features, materials used and radius of any corners or edges. vi 1 INTRODUCTION In the UK, the Health and Safety Executive (HSE) and the Health and Safety Commission (HSC) are responsible for regulating risks to health and safety in the work place.