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Occupant casualties in bus and coach traffic: injury and crash mechanisms
Umeå University, Faculty of Medicine, Surgical and Perioperative Sciences.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: The relevance of conducting this thesis is evident by the fact that bus and coach casualties have been “stubbornly stable” in Europe recent years and a need for investigating if a similar trend could be found in Sweden is therefore obvious. It was also important to add new knowledge to the bus and coach research in Sweden, since many areas were scarcely addressed.

Aims: To describe bus and coach occupants’ injuries, crash and injury mechanisms generated in a traffic environment based on data from the medical sector. Additional aims were to investigate the injury reducing effect of a 3-point belt, the effect of cross-winds, and crucial factors in the emergency- and rescue response.

Material and methods: Injury data analyses were based on a complete ten-year medical data set from a catchment-area with about 130,000 inhabitants. A number of crash studies with the scope in different crash phases were conducted by applying and elaborating the Haddon matrix as a framework. An additional framework, Protocol for Major Incidents was used in order to investi-gate the emergency- and rescue response to a severe coach crash.

Results: Between the first and second five-year period, the incidence of injured in non-crash in-cidents was increased by 24%. In non-crash incidents, 54% were injured; 2/3 while alighting from a bus or coach. The pre-crash factor cross-wind, in addition to vehicle design, vehicle speed and road friction, was investigated in ten crashes. It was confirmed that cross-wind, in relation to vehicle speed and slippery road conditions, needs more attention. The importance of goods load-ing and passengers’ position in the bus, was indicated by the fact that a displacement of the cen-tre of mass rearwards with 10% increased the necessary coefficient of friction with, on average 45%, which in many cases corresponded to dry road conditions. Three Swedish rollover crashes were analysed with regard to the injury outcome, mechanisms and the possible injury reduction for occupants using a safety belt. A considerable increase in safety for occupants belted with 3-point belts was shown through limiting interior contacts, occupant interaction and the possibility of ejection. Crucial post-crash factors in the emergency- and rescue response showed that ordi-nary ways of working and equipment are not always useful and proper equipment for lifting a coach body is essential in the case of a rollover. Finally, the communication between the hospitals is important, and the telephone systems may be overloaded by calls from worried relatives and media.

Conclusions: In non-crash events: Non-crash events constitute a majority of all bus and coach casualties with a high proportion of elderly female occupants among the MAIS 2+ injury cases. Boarding and, especially alighting causes many injuries to the lower extremities.

In the pre-crash phase: Cross-winds do affect the safety of buses and coaches and requires more at-tention. Seat belt usage among bus and coach occupants has to be increased.

In the crash phase: Rollover and ejection are the major causes behind serious and fatal injuries to bus and coach occupants, consequently, retentive glazing, pillars or rails need more attention. An upgrade from 2-point seat belts to 3-point seat belts yields an increase in the estimated injury re-duction from approximately 50% up to 80% for the MAIS 2+ casualties in a rollover crash.

In the post-crash phase: In order to be able to lift a coach body proper equipment originated from experience and development is essential in a rescue operation of a crashed bus or coach. Fur-thermore, to improve the emergency response inside crashed coaches proper methods originated from experience need to be developed.

Euro NBAP: Based on the results and conclusions generated in this thesis, a European New Bus and Coach Assessment Programme is suggested, which would provide bus and coach occupants with a assessment programme similar to the Euro NCAP.

Place, publisher, year, edition, pages
Umeå: Kirurgisk och perioperativ vetenskap , 2005. , 160 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 951
Keyword [en]
Surgery, bus, coach, aerodynamics, crash, non-crash, cross-wind, injuries, weight distribution, road friction, restraints, haddons matrix, prevention, severe crash, mass casualty, major incident, alighting, boarding, incidents
Keyword [sv]
Kirurgi
National Category
Surgery
Research subject
Surgery
Identifiers
URN: urn:nbn:se:umu:diva-482ISBN: 91-7305-829-7 (print)OAI: oai:DiVA.org:umu-482DiVA: diva2:143554
Public defence
2005-04-22, Sal B, Tandläkarhögskolan, Norrlands Universitetssjukhus, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2005-03-24 Created: 2005-03-24 Last updated: 2009-11-09Bibliographically approved
List of papers
1. Injury events among bus and coach occupants - Non-crash injuries as important as crash injuries
Open this publication in new window or tab >>Injury events among bus and coach occupants - Non-crash injuries as important as crash injuries
Show others...
2005 (English)In: International Association of Traffic and Safety Sciences: Research, ISSN 0386-1112, Vol. 29, no 1, 79-87 p.Article in journal (Refereed) Published
Abstract [en]

A ten year complete data set from the health sector, comprising 284 injured bus and coach occupants from a well defined area, was analyzed. The annual injury incidence was 2 per 10,000 inhabitants, 3/4 were women. In non-crash incidents, 54% were injured; 2/3 while alighting from a bus or coach. In crashes, 46% were injured; 2/3 in collisions with other vehicles and 1/3 in single vehicle crashes. During October-March, 3/4 were injured. In two single vehicle mass casualty crashes in slippery road conditions, high built coaches were hit by so high cross wind forces that they were blown off the road. This crash mechanism has received little attention earlier. Of those injured in collisions with other vehicles, 78% were injured in collisions with other heavy vehicles. Slippery conditions contributed to half of the alighting injuries. The proportion of moderate or more serious injuries (MAIS 2+) was highest in single vehicle crashes (48%) and in alighting and boarding (43%) incidents, and was lowest (5%) in collisions. Every seventh injured was treated as an in-patient on average in five days. Non-crash victims consumed 57% of all in-patient days. Conclusions: The aerodynamic cross-wind factor merits more studies. Injury reducing measures against alighting injuries, addressing especially step height and slippery conditions, may have a great potential to reduce these injuries. Rear-end collisions by other heavy vehicles in urban areas, causing a high number of “whip-lash" injuries, also need to be further addressed. The newly introduced law on compulsory seat belt use in long distance coaches may have a potential to reduce single vehicle crash and some collision injuries.

Identifiers
urn:nbn:se:umu:diva-6131 (URN)
Available from: 2007-12-06 Created: 2007-12-06 Last updated: 2009-11-09Bibliographically approved
2. The Haddon matrix, a tool for investigating severe bus and coach crashes
Open this publication in new window or tab >>The Haddon matrix, a tool for investigating severe bus and coach crashes
2003 (English)In: International Journal of Disaster Medicine, ISSN 1503-1438, E-ISSN 1651-3037, Vol. 1, no 2, 109-119 p.Article in journal (Refereed) Published
Abstract [en]

Objective: The aim of the study was to use the Haddon matrix to analyse crash and injury mechanisms in a severe coach crash, to investigate if a safety belt would have reduced injuries, and highlight the triage problem in a mass casualty situation during severe circumstances. Methods: A specific coach crash was chosen as the subject for the case study. All 34 occupants on board were interviewed about the crash, their injuries, and how they sustained their injuries. Medical records concerning ambulance and hospital treatment have been examined. Police reports and other documents concerning the vehicle, weather conditions and the road have been examined. The materials were structured in different cells according to Haddon's matrix. Results: The coach went off a road via a guard-rail and landed on the right side, in a 90° position right across a small river. The main reason for the coach to deviate from the road was strong and gusty side winds imposing lateral forces on the coach, making steering impossible. The impact from the crash was greatest in the front part of the coach, as this part fell 3 metres from the bridge guard-rail down to the river bank. The most frequent injury mechanism was that occupants were hit by other falling occupants. Most occupants would have benefited from having worn seat belts. Ten ambulances and one helicopter from different locations were called upon and the first ambulance arrived 30 minutes after the alarm (a 67-km drive). The helicopter, with an anaesthetist on board, arrived after 1 hour and 20 minutes (a 120-km flight). Nine occupants with moderate injuries and 10 seriously or severely injured occupants were transported by ambulance or helicopter to the hospital. Fifteen occupants, triaged as priority 3, were transported by a chartered coach to hospital where they arrived after about 3 hours. Conclusion: If 100% of the occupants had used a two-point belt, about two-thirds of the injured occupants with MAIS 2+ injuries would have sustained an injury reduction. A further injury reduction by roughly 20% could have been achieved by shifting from two-point belts to three-point belts. Triage of injured occupants could be different from normal practice because of the limited space inside a coach, and the use of ordinary equipment is not always possible inside a crashed vehicle. The fact that most of the side windows remained in position after the crash probably prevented many occupants from serious and fatal injuries caused by ejection or partial ejection.

Keyword
Haddon's matrix, bus, coach, injuries, prevention, severe crash, mass casualty
Identifiers
urn:nbn:se:umu:diva-6560 (URN)10.1080/15031430310035272 (DOI)
Available from: 2007-12-14 Created: 2007-12-14 Last updated: 2010-04-14Bibliographically approved
3. Wind forces and aerodynamics: contributing factors to compromise bus and coach safety?
Open this publication in new window or tab >>Wind forces and aerodynamics: contributing factors to compromise bus and coach safety?
2005 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, Vol. 10, no 5, 435-444 p.Article in journal (Refereed) Published
Abstract [en]

A bus in motion is affected by aerodynamical side and lift forces that may interfere with the stability of the vehicle. These forces depend on the speed and direction of the resulting wind in relation to the bus. Cross-wind gusts may generate side forces so suddenly that great directional deviation is imposed on the bus prior to any possible driver or vehicle manoeuvre responses. Prevailing friction forces may not be sufficient to enable the driver to avoid large lateral deviation from the desired route, and can potentially lead to crashes. The present study, based on ten bus crashes, aimed to show that the effect of wind, in addition to vehicle speed and road friction, is a contributing factor to compromising bus safety. The results of the study confirmed that wind, in relation to vehicle speed and friction, needs more attention when addressing the pre-crash factors in crash investigations, bus manoeuvring capacities, operational management, and the aerodynamic design of buses.

Keyword
Bus, coach, aerodynamics, crash, injuries, weight distribution, road friction
Identifiers
urn:nbn:se:umu:diva-6130 (URN)10.1533/ijcr.2005.0355 (DOI)
Available from: 2007-12-06 Created: 2007-12-06 Last updated: 2010-04-14Bibliographically approved
4. Case study: 128 injured in rollover coach crashes in Sweden - injury outcome, mechanisms and possible effects of seat belts.
Open this publication in new window or tab >>Case study: 128 injured in rollover coach crashes in Sweden - injury outcome, mechanisms and possible effects of seat belts.
Show others...
2006 (English)In: Safety Science, ISSN 0925-7535, Vol. 44, no 2, 87-109 p.Article in journal (Refereed) Published
Abstract [en]

The risk for injuries in rollover coach crashes are dependent on whether the occupants are belted or not. However, the influence of the different belt systems for reducing injuries has remained unclear. Since many injuries sustained are caused by impacts with the interior, passenger interactions or ejection through a window, the advantages by proper seat belt systems are evident. In this study, representing the most common serious crash scenario for serious injury, 128 injured in rollover cases were analysed with regard to the injury outcome, mechanisms and the possible injury reduction for occupants when using a safety belt. Furthermore, the different belt systems were compared to explain their contribution to increased safety. Based on medical reports and questioning of the passengers, the injuries sustained are recorded according to the AIS classification. The next step was the identification of the injury mechanisms, using the passenger statements as well as results from numerical occupant simulations. It is important to mention that this study was purely focused on detection of the injury mechanism to avoid the reported injuries. The possibility of additional injuries due to the wearing of a belt were not taken into account. However, the analysis of the 128 injured showed a considerable increase in safety for belted occupants through limiting interior contacts, minimising passenger interaction and reducing the possibility of ejection.

Keyword
Coach crash, Rollover, Injuries, Seat belt, Injury mechanism, Simulations
Identifiers
urn:nbn:se:umu:diva-6127 (URN)10.1016/j.ssci.2005.07.005 (DOI)
Available from: 2007-12-14 Created: 2007-12-14 Last updated: 2009-11-09Bibliographically approved
5. Protocol from the coach crash in Ängelsberg, Sweden, January 2003
Open this publication in new window or tab >>Protocol from the coach crash in Ängelsberg, Sweden, January 2003
2004 (English)In: International Journal of Disaster Medicine, ISSN 1503-1438, Vol. 2, no 3, 93-104 p.Article in journal (Refereed) Published
Abstract [en]

The crash took place on Friday, 24 January 2003. Due to technical problems, a train was cancelled in Ludvika, a village in central Sweden. A replacement coach was to transport the passengers 115 km to Vsters, via the same route. In darkness, at 4.23 pm, i.e. during working hours, the coach went off the road on a left-hand curve. The driver reduced the speed to 49 km/h before the curve, but lost control of the coach, which skidded off the road, down a high road bank and landed on its right side. The coach's structural damage was mainly located on the right side. Of the 49 occupants, 11 were partially or totally ejected, and 6 were fatally injured. Forty occupants had injuries classified as ISS 1-15, three as ISS 16-30 and six as ISS 41-75. All those in the last group sustained fatal injuries.

Keyword
Bus, coach, major accident, mass casualty, major emergency, disaster, trauma, injuries
Identifiers
urn:nbn:se:umu:diva-6561 (URN)10.1080/15031430510028665 (DOI)
Available from: 2007-12-14 Created: 2007-12-14 Last updated: 2009-11-09Bibliographically approved

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