CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES

Transcription

1 CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES

2 CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES Narelle Haworth Peter Vulcan Lyn Bowland Nicola Pronk Monash University Accident Research Centre September 1997 Report No. 120

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5 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE REPORT DOCUMENTATION PAGE Report No. Date ISBN Pages 120 September xii app Title and sub-title: Characteristics of fatal single vehicle crashes Author(s) N. Haworth, P. Vulcan, L. Bowland and N. Pronk Type of Report & Period Covered: General, Sponsoring Organisation(s): This project was funded through the Centre s Baseline Research Program for which grants have been received from: Department of Justice Royal Automobile Club of Victoria (RACV) Ltd Roads Corporation (VicRoads) Transport Accident Commission Abstract: This report describes the characteristics of a set of 127 fatal single-vehicle crashes which occurred within 200 km of Melbourne during the period from 1 December 1995 to 30 November The crashes comprised the cases for the Case-control study of fatal single-vehicle crashes. The main identifiable factor contributing to the occurrence of fatal single vehicle crashes in this study was BAC>.05 (and particularly BAC>.15) and the main identifiable factors contributing to the degree of severity of the crashes appeared to be impacts with trees and poles and some older vehicles which are unlikely to comply with most of the current safety standards. A number of possible improvements to procedures for the investigation of serious injury crashes are recommended. Key Words: (IRRD except when marked*) Single vehicle accident, fatality, drink driving, marijuana, driver characteristics, vehicle, road environment, pole, vegetation. Reproduction of this page is authorised Monash University Accident Research Centre, Wellington Road, Clayton, Victoria, 3168, Australia. Telephone: , Fax: CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES iii

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7 EXECUTIVE SUMMARY This report describes the characteristics of a set of 127 fatal single-vehicle crashes which occurred within 200 km of Melbourne during the period from 1 December 1995 to 30 November The crashes comprised the cases for the Case-control study of fatal single-vehicle crashes. The cases have location, driver/rider and vehicle characteristics. The controls are (non-crash) trips which also have location, driver/rider and vehicle characteristics. The comparisons of cases and controls to derive relative risk estimates are presented in the companion report entitled Estimation of risk factors for fatal single-vehicle crashes. A summary of the overall study has also been produced (Single vehicle crash study: Summary report). The aims of the Case-control study of fatal single-vehicle crashes study were to: 1. investigate single vehicle crashes to determine the circumstances and factors contributing to them 2. estimate the over-involvement (relative risk) of these factors 3. identify improvements in procedures for the investigation of road deaths and life threatening injuries 4. provide information from which countermeasures can be developed to the agencies responsible for road safety in Victoria This report addresses aims 1 and 3. CHARACTERISTICS OF THE CRASHES There were 127 single vehicle crashes in which 133 persons were killed. The crashes had the following characteristics: Type of crash almost 75% of crashes involved an impact with a tree or pole or both (71% of metropolitan, 78% of rest of study area crashes) tree crashes were more common outside the metropolitan area 53% of trees and 36% of poles impacted were in the median or on the righthand side of the road 31% of crashes involved impact with a tree or pole located within the desirable clear zone outlined in VicRoads policy Temporal characteristics crashes were most common from midnight to 6 am and midday to 6 pm crashes were most common on Saturdays and Sundays there were no clear seasonal effects CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES v

8 Persons killed five crashes were multiple fatalities the driver was killed in 81% of crashes almost half the persons killed were aged under 25 Drivers and riders 80% were male more than 40% were aged under 25 natural disease (particularly heart disease) was the cause of death for at least 60% of the drivers aged 60 and over 13% had been severely depressed in the previous six months 13% did not hold a current licence (6% never held a licence, 2% licence lapsed, 6% licence disqualified) Alcohol and other drugs BAC was known for 95% of crashes and cannabis known for 83% of crashes. The percentages in this section are percentages of known cases. All of the cases of cannabis being present were in deceased drivers where it was detected as the metabolite, carboxy-thc. This substance may be detected some weeks after cannabis use and therefore its detection does not prove that the driver was under the influence of cannabis at the time of the crash. BAC>.05 in 36%, BAC>.15 in 27% of crashes cannabis was most commonly found in conjunction with alcohol: for BAC>.05, cannabis was present in 49% for BAC>.15, cannabis was present in 52% but for BAC<.05, cannabis was present in only 6% males were twice as likely as females to have BAC>.05 but the proportions of these with BAC>.15 were similar for males and females no alcohol or cannabis was present in drivers aged 60 and over drivers aged 25 to 59 were more likely to have BAC>.15 than those under 25 higher levels of education were related to fewer drivers with BAC>.05 or cannabis for 25 to 59 year olds but not for under 25s proportions of crashes with BAC>.05 or cannabis were similar in metropolitan and rural areas BAC>.05 was found more often on major roads than freeways, highways or minor roads cannabis was detected for 23% of male drivers and 11% of female drivers cannabis was detected in 21% of those under 25 and 25% of those aged 25 to 59 cannabis-involved crashes were less common on highways than freeways, major roads or minor roads information about consumption of prescription and nonprescription drugs was available for 78% and 73% of drivers, respectively 17% of drivers had taken prescription drugs in the 12 hours prior to the crash (14% of under 25s, 18% of 25 to 59s and 27% of those aged 60 and over) 3 drivers or riders had taken nonprescription drugs in the 12 hours prior to the crash vi MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

9 Passengers 74 passengers of whom 30 were killed were more likely to be of the same sex as the driver than to be of the opposite sex or at least one of each sex young drivers were more likely to have passengers than other drivers most passengers were in the same age group as the driver of the vehicle (particularly for under 25s) in four of the 24 crashes for which BAC of both driver and (killed) passenger were known, the BAC of the driver was greater than that of the passenger Vehicles 10 crashes involved motorcycles, 7 involved light commercial vehicles and 3 involved trucks six of the 10 motorcycles had an engine capacity of greater than 500 cc but none of the motorcycles with an engine capacity greater than 260 cc was ridden by a learner or probationary rider almost 20% of the vehicles involved in crashes were manufactured before 1978 and so were not required to comply with some of the current safety standards age of the vehicle was not related to age of the driver Locations of crashes 60% of crashes occurred in Melbourne metropolitan area, 40% in the remainder of the study region most crashes occurred on highways (42%) a larger proportion of crashes occurred on highways and a smaller proportion on minor roads in the metropolitan area compared to the rest of the study area two-thirds of the crashes occurred on undivided roads (58% of metropolitan, 77% of rest of study area) half of the crashes occurred where the speed limit was 100 km/h or 110 km/h (23% of metropolitan, 82% of rest of study area) about one-third of the crashes occurred on curves (27% of metropolitan, 36% of rest of study area) 20% of metropolitan and 8% of rest of study area crashes occurred at intersections (most commonly T intersections) traffic controls were present at the site of 13% of crashes (18% of metropolitan, 6% of rural) mud, oil or loose material was present on the road surface for 10% of crashes in the rest of the study area the road had a shoulder for 62% of metropolitan crashes and 96% of rural crashes. In the metropolitan area, 49% of shoulders were sealed compared with 20% of rural shoulders POSSIBLE IMPROVEMENTS IN INVESTIGATION PROCEDURES In order to improve the availability of information about severe crashes, it was recommended that: CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES vii

10 1. The availability of toxicological information for drivers who may be charged be investigated and, if necessary, a procedure be developed to incorporate the BAC data into the State Traffic Accident Record at an appropriate time (perhaps after completion of criminal procedures). 2. Given the lack of information on drugs in nonfatal crashes, perhaps testing of all (or a given proportion) of blood samples for drugs should be undertaken for a specified period to increase our knowledge in this area. 3. Blood samples of all drivers in fatal crashes (whether or not injured) be taken and analysed for both alcohol and other drugs. An alternative would be to have blood samples taken and analysed whenever the breath shows alcohol (building on the strong relationship between alcohol and cannabis). 4. The family s right to object to autopsy be maintained but that the authorities have the right to take and analyse a blood sample from the deceased. 5. Testing for the active ingredient, rather than the metabolite, of cannabis be undertaken, at least for fatal crashes in the short term. Improvements in technology may reduce costs etc and allow this to be extended to nonfatal crashes in the future. 6. Vehicle Identification Numbers (VINs) be recorded to allow better identification of makes and models of vehicles and judgements of the presence of safety features. Currently, VINs could be added to the State Traffic Accident Record routinely by interrogating the registration data, using the vehicle registration number. In the future, automatic capture of VINs at the crash site may replace this method. 7. In addition, for the next couple of years, it would be desirable if deployment of airbags could be recorded. 8. It is probably preferable for items regarding the state of the vehicle immediately prior to the crash (e.g. heating and ventilation) to be collected in special studies, rather than to burden the Police with additional workload for every reported crash. 9. While resource limitations are an important issue which needs to be considered, it may be useful from the point of view of training Accident Investigation Section staff and developing a high quality knowledge base for prevention, to have a special focus on particular crash types (or perhaps even locations) for a particular period. viii MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

11 TABLE OF CONTENTS Page Acknowledgments xi 1. Introduction Background to the study Outline of the study Aims of the study Structure of reporting 2 2. Study design and procedure Crash types included Study region Questionnaire Roles of the agencies involved Victoria Police Accident Investigation Section State Coroners Office Monash University Accident Research Centre Case review meetings 5 3. General characteristics of cases Type of crash Temporal characteristics of the crashes 8 4. Persons involved Persons killed Demographics of drivers and riders Licensing Alcohol and other drugs Toxicology reports Alcohol and cannabis Correlates of alcohol use Sex of driver or rider Age Level of education Location of crash Licensing Correlates of cannabis use Sex of driver or rider Age Education Location of crash Licensing Prescription and nonprescription drugs Passengers 21 CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES ix

12 Page 5. Vehicles involved Types of vehicles involved Heating and ventilation Sound Vehicle defects Locations of crashes Type of road Speed limit Road geometry Type of intersection Delineation Road furniture Traffic controls and Local Area Traffic Management devices The road surface Road shoulder Roadside objects Environmental factors Crashes involving trees and poles Distances to impacted trees and poles Comparisons with the VicRoads Clear Zone Policy Crashes with trees and poles on curves Summary of characteristics of crashes Discussion Alcohol and cannabis Comparisons with other data sources Possible improvements in investigation procedures Alcohol Other drugs Recording vehicle data AIS attendance criteria 51 References 52 Appendix 1: Crash questionnaire Appendix 2: Coding modifications to vehicles Appendix 3: Summary of cases Appendix 4: Concentrations of cannabis metabolite x MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

13 ACKNOWLEDGMENTS This study could not have been undertaken without the considerable efforts of the Victoria Police Accident Investigation Section and Traffic Operations Group and the State Coronial Services Centre. We acknowledge their dedication and commitment to the study. The technical input and support of the Project Steering Committee is appreciated. The members of the Committee were: Graeme Johnstone, State Coroner Isadora Engert - State Coroner s Office Bob Wylie, Neil O Sullivan, Noel Osbourne - Victoria Police Ted Vincent, Mike Regan, Mike Tziotis, Bob Gardner, Phillip Jordan - VicRoads David Healy - Transport Accident Commission Karen McIntyre, Peter Doupé, Anne Harris - RACV David Ranson - Victorian Institute for Forensic Medicine Many of our colleagues at MUARC provided valuable advice during the study. We would like to acknowledge the traffic engineering input of Bruce Corben and the statistical advice of Max Cameron, Lesley Day and Caroline Finch. Thank you also to the drivers and riders who agreed to be interviewed for the study. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES xi

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15 1. INTRODUCTION 1.1 BACKGROUND TO THE STUDY Single vehicle crashes resulted in 134 deaths and 1898 persons seriously injured in Victoria during 1995 (VicRoads, 1996). The monetary cost to the community of these types of crashes is estimated to be about $450 million. Overall, single-vehicle collisions comprise approximately 30% of road trauma in Victoria. The study arose from concern by the Victoria Police and the State Coroner that there was a need for a better understanding of the causative factors in single vehicle runoff-road crashes. Traditionally, Police investigation of these crashes has often been rudimentary when the driver has been killed (and so prosecution is not possible). Since driver-killed crashes comprise about three-quarters of all fatal single-vehicle crashes, the lack of detailed investigation of these crashes has prevented the development of a clear understanding of the factors involved. The Police and Coroner, in consultation with the Transport Accident Commission and Vic Roads, decided that there was a need for a multi-disciplinary approach which would go beyond the attribution of blame. The study was very much a cooperative venture between the State Coroner s Office, Victoria Police Accident Investigation Section, Victoria Police Traffic Operations Group and Monash University Accident Research Centre. In most past studies, crash types have been studied in a descriptive manner, focussing on in-depth investigation to identify those factors which contribute to crash occurrence or injury severity. The lack of a control group in these studies, however, has made it difficult to test whether the factors identified truly increase crash risk or are merely common characteristics of the road users, vehicles and locations involved. Increasingly, the epidemiological tool of the case-control study is being applied to investigation of road safety problems, as it is in medical research (e.g. cancer). Thus this case-control study aimed to identify the factors which contribute to an increased risk of occurrence of fatal single vehicle crashes, an important step in developing countermeasures to address the problem. 1.2 OUTLINE OF THE STUDY The Case-control study of fatal single-vehicle crashes collected detailed information about cases and controls. The cases are fatal single-vehicle crashes (or crash trips) which occurred during the period from 1 December 1995 to 30 November The cases have location, driver/rider and vehicle characteristics. The controls are (non-crash) trips which also have location, driver/rider and vehicle characteristics. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 1

16 The study collected three types of information: detailed descriptive information about the crash and the resultant injuries comparisons of the features of cases and controls, and general exposure information (gathered as part of the control collection process). 1.3 AIMS OF THE STUDY The aims of the study were: 1. to investigate fatal single vehicle crashes to determine the circumstances and factors contributing to them 2. to estimate the over-involvement (relative risk) of these factors 3. to identify improvements in procedures for the investigation of road deaths and life threatening injuries 4. provide information from which countermeasures can be developed to the agencies responsible for road safety in Victoria This report addresses aims 1 and STRUCTURE OF REPORTING This report describes the characteristics of the crashes which comprised the cases for the Case-control study of fatal single-vehicle crashes. The comparisons of cases and controls to derive relative risk estimates are presented in the companion report entitled Estimation of risk factors for fatal single-vehicle crashes. A summary of the overall study has also been produced (Single vehicle crash study: Summary report). 2 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

17 2. STUDY DESIGN AND PROCEDURE 2.1 CRASH TYPES INCLUDED This phase of the study included only fatal single-vehicle crashes (rather than fatal and serious injury crashes) to limit the demands on Police resources and to enable Police involvement in the study to be maintained for a full year. Fatal single-vehicle crashes were defined in the following terms for the purposes of this study - where a collision occurs involving a single vehicle, resulting in the death of occupants of that vehicle, in either (sic) of the following circumstances: 1. collision with a fixed object (on/off road) 2. collision with parked vehicle 3. rollover collisions. This definition differs from that used by Vic Roads in the State Traffic Accident Record in several ways: it does not include crashes where a vehicle impacts a pedestrian it does not include crashes involving falling from or in a moving vehicle it includes crashes in which a moving vehicle impacts a stationary vehicle. The study included all fatal single-vehicle crashes in the study region, regardless of the type of vehicle involved. 2.2 STUDY REGION The study region comprised the area in Victoria within a 200 km radius of Melbourne. It stretched from Sale in the east, to Wangaratta and Echuca in the north, to Ararat in the west (see Figure 2.1) and included most of the major population centres in Victoria. 2.3 QUESTIONNAIRE The crash questionnaire was developed based on questionnaires used in the University of Auckland Case-Control Study of Motorcycle Crashes (personal communication) and input from the Project Steering Committee. A copy of the questionnaire used in this study is included as Appendix 1. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 3

18 Figure 2.1. The study region. MUARC provided blank crash questionnaires to the Victoria Police Accident Investigation Section (AIS), individually ring bound to keep all of the contents together and to make them more easily identifiable. The sections were colour-coded to facilitate completion. A manual for the crash questionnaire was developed by MUARC in consultation with the AIS and issued to each AIS team. The questionnaire for each case was completed by the investigating officer. Following discussion with Vic Roads Vehicle Safety Standards section, a set of categories were developed for the question, Have any modifications been made to the vehicle?. The coding guidelines are presented in Appendix ROLES OF THE AGENCIES INVOLVED The study was very much a cooperative venture between the State Coroner s Office, Victoria Police Accident Investigation Section, Victoria Police Traffic Operations Group and the Monash University Accident Research Centre. The roles played by these agencies in the research are outlined below Victoria Police Accident Investigation Section Members of the AIS attended the scene of the crash and conducted the investigations necessary to complete the crash questionnaire. This included conducting inspections of the site of the crash. The AIS Coordinator collected questionnaires from attending officers and forwarded them to MUARC. 4 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

19 The AIS Coordinator faxed notifications of crashes to the Coronial Services and MUARC each weekday. A special series of job numbers, prefixed with SV, was used for the study. The notification sheets included the following items: job number, date of crash, date of death (if delayed), time of crash, location of crash, nature of crash (e.g. struck pole, struck tree, rollover), AIS member attending, vehicle make and model, year of manufacture, name and address of deceased. In addition to collecting information about crashes, the AIS Coordinator notified the Traffic Operations Group of times and places where their assistance would be needed in the collection of controls (random breath testing and licence checking). The draft crash questionnaire was piloted by AIS members during late November A number of important modifications were made on the basis of AIS input. These included changes to wording and addition of some questions State Coroners Office The Coroners Office coordinated information for fatalities. This included the supply of toxicology reports and autopsy reports when available. While some post mortems were conducted in the country, all country autopsies were overviewed by a pathologist at the Victorian Institute of Forensic Medicine. Inquests were held in the city or the country. Even if there was a Chambers finding rather than an inquest, the data was available to the study. Further inquests may be held up to six months after the end of the study period. Criminal cases may be delayed for up to 18 months or two years Monash University Accident Research Centre MUARC designed and produced the questionnaires and undertook data entry and analysis. 2.5 CASE REVIEW MEETINGS In the initial project discussions, it was decided that at least some of the cases would be reviewed by a panel of experts to better identify the factors that contributed to the occurrence or severity of the crashes and also the manner in which they related to each other. It was also expected that the identification of these factors would provide the opportunity to develop better targeted countermeasures for single vehicle crashes. Case review meetings were held in March 1996, June 1996 and February Seven cases were reviewed during the first meeting. The countermeasure issues which were raised related to the efficacy of the medical review system for driver licensing, the possibility of educating older groups and doctors about fitness to drive, guardrailing of bridge pillars, terminal design for guardrails and educating particular ethnic groups about their susceptibility to alcohol. Other issues discussed included the role of natural disease in crashes and the statistical classification of these crashes. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 5

20 Six cases were presented by the AIS at the second meeting and seven cases at the third meeting. The issues discussed included fatigue caused by driving too long or prescription drugs, safety of driving by overseas visitors, the differences in the effects of alcohol and cannabis, detection of cannabis, airbag effectiveness, appropriateness of speed zoning at some locations and the rural culture of drink driving. While those attending found the case review meetings to be useful, the substantial resources needed to compile the information and hold meetings was acknowledged. It was considered not feasible to review every crash in the study. The Coroner suggested that, because of the time involved, only cases of special interest should be reviewed. 6 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

21 3. GENERAL CHARACTERISTICS OF CRASHES This chapter describes the characteristics of the 127 fatal crashes included in the study. Six additional cases were notified to MUARC but were later withdrawn from the study by the Victoria Police because they did not fit all of the selection criteria for inclusion in the study (because they were out of area, multi-vehicle or pedestrian etc). Appendix 3 summarises the general characteristics of the cases. 3.1 TYPE OF CRASH The following classification of crash types utilises the description provided on the Police notification form. The most common type of crash was an impact with a tree, both in Metropolitan Melbourne and the rest of the study area. As Table 3.1 shows, crashes with trees comprised almost 40% of crashes in Metropolitan Melbourne and more than 60% of crashes in the rest of the study area. Crashes with poles were the second most common type of crash overall, but were much more common in Metropolitan Melbourne (29%) than in the rest of the study area (10%). Rollovers were more common outside of the metropolitan area than in Melbourne (10% versus 4%). A number of the crashes were simply described as off-road on the notification form. Table 3.1. Percentages of crashes according to the type of crash. Crash type Metropolitan area (n=76) Rest of study area (n=51) Overall (n=127) Impact with pole Impact with tree Impact with stationary vehicle Impact with bridge pylon Impact with fence Impact with railing Impact with embankment Rollover Off road Other Total There was evidence of braking for 20 crashes (16%). This comprised rear tyre hooked skid (5), rear tyre weaved skid (fishtailing) (5), straight skid (7) and front tyre skid (3). In two cases the evidence of braking was in relationship to a sudden change in the road surface. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 7

22 3.2 TEMPORAL CHARACTERISTICS OF THE CRASHES The months and the days of the week when the crashes occurred are summarised in Tables 3.2 and 3.3. Crashes were more common in February (14%), April (12%) and September (13%) than in the other months. There does not appear to be a clear seasonal trend in the crashes. Saturday (23%) and Sunday (20%) were the most common days for crashes to occur, with crashes being least frequent on Tuesdays (see Table 3.3). Table 3.2. The months in which the crashes occurred. Month Number of crashes Percent of crashes December 10 8 January 12 9 February March 6 5 April May 8 6 June 9 7 July 8 6 August 11 9 September October 5 4 November 9 7 Total Table 3.3. The days of the week that the crashes occurred. Day of the week Number of crashes Percent of crashes Monday Tuesday 9 7 Wednesday Thursday Friday Saturday Sunday Total More crashes occurred at night (6 pm to 6 am) than during the day (6 am to 6 pm, 54% vs 47%). Crashes were most common from midnight to 6 am and from midday to 6 pm and least frequent from 6 am to midday (see Table 3.4). Figure 3.1 presents the time of occurrence in greater detail. A total of 45 crashes (35%) occurred in the six hour period between 10 pm and 4 am. The crash frequencies were generally highest from 2 am to 4 am and 10 pm to midnight. Many of the crashes between 2 am and 4 am occurred on Friday, Saturday or Sunday mornings (see Figure 3.2). 8 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

23 Table 3.4. The times of day that the crashes occurred. Time of day Number of crashes Percent of crashes Midnight to 6 am am to midday Midday to 6 pm pm to midnight Total Figure 3.1. Number of crashes during each two-hour period of the day Number of crashes Time of day Figure 3.2. Percentages of crashes during each two-hour period of the day separately for weekdays and weekends. Weekends are Friday, Saturday, Sunday. 25 Percent of crashes Weekday Weekend Time of day CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 9

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25 4. PERSONS INVOLVED 4.1 PERSONS KILLED A total of 133 persons were killed in the 127 crashes. The five multiple fatality crashes comprised three in which the driver (or rider) and one passenger were killed, one in which the driver and two passengers were killed and one in which two passengers were killed (see Table 4.1). The driver (or rider) was killed in 103 crashes (81%). Table 4.1. Persons killed in fatal single vehicle crashes. Persons killed Number of crashes Percent of crashes Driver (or rider) only One passenger only Driver (or rider) and one passenger 3 2 Driver and two passengers 1 1 Two passengers 1 1 Total Overall, 74% of those killed were male (81% of drivers or riders, 53% of passengers). Table 4.2 presents information about the ages of the persons killed. About 45% of the persons killed in the crashes were aged under 25. About 12% of the persons killed were aged 60 or over. Table 4.2. Age groups of people killed in fatal single vehicle crashes. Age group Drivers and riders Passengers All occupants Under to and over Total DEMOGRAPHICS OF DRIVERS AND RIDERS Overall, 80% of the drivers and riders in the crashes were male. The ages of the drivers and riders involved in the crashes are summarised in Figure 4.1. More than 40% of the drivers were aged under 25. Less than 12% of the drivers were aged over 60. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 11

26 Figure 4.1. Age groups of drivers and riders involved in fatal single vehicle crashes Percent of crashes Under to to to to to and over Age group Overall, 54% of the drivers or riders were single (see Table 4.3). Not surprisingly, a larger proportion of the youngest group were single and only the oldest group contained widows (including widowers). The marital status of four drivers or riders had changed during the last 12 months: one under 25 year old had married, two 25 to 59 year olds had separated and one 25 to 59 year old had divorced. Table 4.3. Percentages of drivers or riders according to marital status. Marital status Age group Under 25 (n=52) 25 to 59 (n=60) 60 and over (n=15) Total (n=127) Single Married or living with partner Separated or divorced Widowed Unknown Total The highest level of education most commonly received by drivers or riders was secondary school (see Table 4.4). Not surprisingly, University education was most common among the youngest group. None of the drivers aged 60 and over were in full-time work, the majority were receiving a benefit (see Table 4.5). About half of 12 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

27 the drivers or riders in each of the other two age groups were in full-time work. Almost one-quarter of the under 25s were students. Table 4.4. Percentages of drivers or riders according to highest level of education received. Level of education Age group Under 25 (n=52) 25 to 59 (n=60) 60 and over (n=15) Total (n=127) Primary school Secondary school TAFE University Unknown Total Table 4.5. Percentages of drivers or riders according to present job situation. Individuals can belong to more than one category so totals may exceed 100%. Job situation Age group Under 25 (n=52) 25 to 59 (n=60) 60 and over (n=15) Total (n=127) Full-time work Part-time work Receiving benefit Student Self employed Home maker Unemployed and no benefit Other Unknown Whether the driver or rider worked shifts was known for 83/127 crashes. Fifteen drivers or riders worked shifts, six who were aged under 25 and nine who were aged 25 to 59. The number of days since the driver or rider had a day off was known for 55 crashes. Only two of these drivers had worked for more than seven days since their last day off. The variable was not coded for those who were unemployed or receiving a pension or benefit. Whether the driver or rider had felt severely depressed at any time in the last six months (e.g. required treatment or attempted to take his/her life) was recorded for 109 of the 127 crashes. Fourteen of the drivers (13% of known) had been severely depressed. Fifteen drivers were reported to have had a disability. The disabilities recorded included angina (2), deafness (2) and diabetes (2). Coroners briefs were available for 10 of the 15 drivers aged 60 or over. Reading of the briefs showed that the cause of death was related to heart disease, rather than CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 13

28 injuries sustained in the crash, for seven of these ten drivers. Other diseases were noted as possible causes of the crash for two other drivers. For only one driver was it noted that death resulted from injuries sustained in the crash. 4.3 LICENSING The types of licences held by the drivers and riders are summarised in Table 4.6. Overall, 13% of drivers or riders did not hold a current licence. Of these, 6% had never held a licence (all aged under 25), 6% had their licence disqualified and 2% had allowed their licence to lapse. Table 4.6. Type of licence held by the driver or rider. Some drivers or riders held multiple types of licence. Type of licence held Number of crashes Percent of crashes Never held licence 7 6 Licence lapsed 2 2 Licence disqualified 7 6 Learner 5 4 Probationary Full car Motorcycle 9 7 Light truck 3 2 Heavy truck/bus 6 5 Articulated truck 7 6 Other 3 2 Unknown 2 2 Five car drivers (4%) held a learners permit. At the time of the crash two of the learners were not accompanied by a licensed driver (there were no passengers). Of the 25 probationary drivers, only two were aged 25 and over. Seven of the ten motorcycle riders in the crashes held a current motorcycle licence. One rider had never been licensed, one was disqualified and information is unavailable for the remaining rider. Information about driver training was available for 101 drivers or riders. Five car drivers had undertaken a training course of some kind. One motorcyclist had completed a course for beginners. 14 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

29 4.4 ALCOHOL AND OTHER DRUGS There were several sources of information about the presence of alcohol and other drugs in crashed drivers. Toxicology reports were prepared for deceased drivers. Some injured drivers had blood tests taken for analysis for alcohol and/or other drugs. Some uninjured drivers were breath tested for alcohol Toxicology reports Toxicology reports were available for 98 drivers or riders and 24 passengers from 118 crashes. These reports are summarised in Table 4.7. Forty-two drivers or riders (43% of reports) were drug free. The general BAC limit of.050 was exceeded by 36 deceased drivers or riders (37% of reports), but in 22 of these cases, other drugs were also present. Cannabinoids were detected in 22 drivers or riders (22% of reports), in all but four cases this was in conjunction with alcohol. This pattern is shown in Figure 4.2. Figure 4.2. The prevalence of alcohol, cannabis and other drugs in the 98 deceased drivers and riders for whom toxicology reports were available. In this figure, persons with BAC less than.050 and no other drug are classified drug-free. Other drugs 14% Alcohol and other drugs 4% Alcohol 14% Alcohol and cannabis 18% No drugs 46% Cannabis 4% CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 15

30 Table 4.7. Summary of toxicology reports received. Type of drug identified Driver or rider Passenger Number Percent Number Percent No drugs identified Alcohol (no other drugs) 0.001% to 0.050% % to 0.149% >=0.150% Cannabinoids (no alcohol) Opiates Benzodiazepines Stimulants Antidepressants Analgesics Alcohol and cannabinoids %-0.050% %-0.149% >=0.150% Alcohol >=0.150%, cannabinoids and benzodiazepines Alcohol >=0.150%, cannabinoids, opiates and benzodiazepines Alcohol and other drugs (not cannabinoids) 0.001%-0.050% %-0.149% >=0.150% Opiates and benzodiazepines Other drugs or combinations Total persons Note: Detection of cannabinoids cannot be taken to imply that the driver/rider was affected by this drug at the time of the crash. Detection implies only that the substance was used during the last several weeks Alcohol and cannabis Table 4.8 summarises the availability of data relating to alcohol and other drugs. For the 24 surviving drivers, results of breath tests for alcohol were available for nine drivers and results of blood tests for alcohol were available for 14 drivers. Toxicology reports were received for 98 of the 103 deceased drivers. 16 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

31 Table 4.8. Summary of information about alcohol and other drugs in crashed drivers. Information available Surviving drivers (n=24) Deceased drivers (n=103) Breath test for alcohol 9 0 Blood test for alcohol 14 0 Toxicology report 0 98 In deceased drivers and riders, cannabis was coded as present if the toxicology report stated that the metabolite (as carboxy-thc) was found in blood or urine. This could result in drugs being coded as present which may have been taken more than 12 hours (or even several weeks) before the crash. Only eight of the 24 surviving drivers and riders provided information about cannabis use in the 12 hours prior to the crash. Each of these drivers said that they had not used cannabis during that period. The reliability of those responses was not able to be tested. The concentrations of the cannabis metabolite detected in killed drivers are summarised in Appendix 4. Table 4.9 summarises the available BAC and cannabis information. Overall, BAC was unavailable for about 5% of crashes and cannabis unavailable for 17% of crashes. BACs of greater than.05 were recorded for 35% of crashes (36% of known). BACs of greater than.15 were found in 26% of crashes (27% of known). Cannabis and alcohol were often found together. For BACs over.05, cannabis was present in 41% (49% of known). For BACs over.15, cannabis was present in 45% (52% of known). There were only four cases of cannabis (4% of known) where BAC<.05. Table 4.9. Numbers of drivers and riders with given blood alcohol concentrations (BACs) with and without cannabis present. BAC Without cannabis (n=83) With cannabis (n=22) Cannabis unknown (n=22) Total (n=127) <= >= Unknown Correlates of alcohol use Sex of driver or rider Overall, 89% of the drivers or riders with BAC>.05 in the study were male. Forty percent of males had BAC>.05, compared with 22% of females (see Table 4.10). CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 17

32 Table Percentages of drivers and riders with given blood alcohol concentrations (BACs) as a function of driver or rider sex. BAC Sex of driver or rider Male (n=102) Female (n=25) Total (n=127) <= >= Unknown Total The proportions of drink drivers whose BAC was over.15 were similar for males and females. While females in single vehicle crashes were less likely to have been drink driving than males, those who had been drink driving were just as likely as males to have had a very high BAC Age The percentages of drivers and riders of each age group at each BAC level are presented in Table None of the drivers or riders aged 60 or over had BACs greater than.04. The proportion of drivers or riders with BAC>.05 was highest for under 25s but those aged 25 to 59 were more likely to have BACs exceeding.15. Table Percentages of drivers and riders with given blood alcohol concentrations (BACs) as a function of age group. BAC Age group Under 25 (n=52) 25 to 59 (n=60) 60 and over (n=15) Total (n=127) <= >= Unknown Total Level of education The relationship between alcohol and level of education is complicated by the relationship between age and level of education. Table 4.12 presents the percentages of drivers or riders with BAC>.05 as a function of level of education and age group. For under 25 year olds, level of education did not affect the percentage with BAC>.05. For 25 to 59 year olds, however, none of those with TAFE or university education had BAC> MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

33 Table Percentages of drivers and riders who had BAC>.05 for each highest level of education received and age group. Highest level of Age group education Under 25 (n=52) 25 to 59 (n=60) 60 and over (n=15) Primary or secondary TAFE or university Location of crash Similar percentages of crashes in the metropolitan area (36%) and the rest of the study area (33%) involved BACs>.05. Drink driving crashes were more common on major roads (59% of crashes on these roads) than on freeways (29%), highways (29%) or minor roads (27%) Licensing Of the 44 drivers or riders with BACs>.05, 22 had full car licences and two riders had motorcycle licences. Eleven of the 44 were novice drivers: nine had probationary licences (3 of these were BAC>.15) and two had learner permits. Five drink drivers had never held a licence, three were disqualified (including one motorcyclist) and one licence had lapsed. One learner driver and two probationary drivers had BACs between zero and.05, in contravention of the licensing restrictions Correlates of cannabis use Sex of driver or rider Cannabis was detected for 20% of male drivers and 8% of female drivers. Overall, 91% of the drivers for whom cannabis was detected were male Age Cannabis was detected in 17% of drivers or riders aged under 25 and 22% of those aged 25 to 59. It was not detected in any drivers or riders aged 60 or over Level of education Table 4.13 shows that the proportion of drivers aged under 25 in whom cannabis was detected did not differ according to level of education but that drivers and riders aged 25 to 59 with TAFE or university education were less likely to have used cannabis. This was the same pattern found for BAC>.05. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 19

34 Table Percentages of drivers and riders with cannabis detected for each highest level of education received and age group. Highest level of Age group education Under 25 (n=52) 25 to 59 (n=60) 60 and over (n=15) Primary or secondary TAFE or university Location of crash Similar percentages of crashes in the metropolitan area (16%) and the rest of the study area involved use of cannabis (20%). Cannabis-involved crashes were less common on highways (10%) than freeways (21%), major roads (24%) and minor roads (23%) Licensing Of the 22 drivers and riders in whom cannabis was detected, 12 had a full car or motorcycle licence. Five were novice drivers: one held a learner s permit and four had probationary licences. Five drivers or riders were unlicensed: two had never had a licence, two had their licences disqualified and one had a licence which had lapsed Prescription and nonprescription drugs Surviving drivers in crashes were asked if they had taken any prescription drugs or nonprescription drugs in the 12 hours prior to the crash. For deceased drivers this information was requested from relatives or treating doctors. Non-prescription drugs were described as medications that you can buy only from the chemist, but without a prescription from a doctor. Information about consumption of prescription and nonprescription drugs was available for 99 and 93 cases, respectively. Seventeen drivers or riders (17% of known) had taken prescription drugs in the 12 hours prior to the crash. This included 14% of under 25s, 18% of 25 to 59s and 27% of those aged 60 and over. Five drivers with BAC>.15 and one driver with BAC>.05 had taken prescription drugs in the previous 12 hours. The prescription drugs which had been taken included asthma preparations (3 persons), benzodiazepines (3), antidepressants (2), blood pressure medication (2), insulin and heart medication. Only three drivers or riders had taken nonprescription drugs in the 12 hours prior to the crash. Two were aged under 25 and one was aged 25 to 59. One of the drivers who had taken nonprescription drugs had BAC> MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

35 4.5 PASSENGERS There were 74 passengers in 48 crashes (38%). The number of passengers was unknown for one crash. The number of passengers per vehicle ranged from 0 to 5. Two of the passengers were pillions on motorcycles (both killed). In total, 30 passengers were killed in the crashes. As Table 4.14 shows, passengers were more likely to be of the same sex as the driver than to be of the opposite sex or at least one of each sex. The young drivers were more likely to have passengers than the older drivers: 56% under 25 drivers had one or more passengers, 25% of year old drivers had passengers, 27% of 60 and over drivers had passengers. Table Percentages of crashes according to the sex of driver and sex of passengers. Crashes with passengers only. Sex of Sex of driver passengers Male (n=37) Female (n=11) Total (n=48) Male Female Mixed Total Table 4.15 shows that most passengers were in the same age group as the driver of the vehicle. This was especially true for under 25 year olds. Table Percentages of crashes according to the age of driver and age of passengers. Crashes with passengers only. The percentages may not add to 100% because there may be passengers in more than one age group in a single crash. Age of passengers Age of driver Under 25 (n=29) 25 to 59 (n=15) 60 and over (n=4) Overall (n=48) and over The BAC of the passenger(s) was known for 24 crashes. In four of these crashes, the BAC of the driver was greater than that of the passenger. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 21

36 22 MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE

37 5. VEHICLES INVOLVED A number of characteristics of the vehicles involved in crashes were recorded and are summarised here. It should be noted that many of the vehicle characteristics may not have contributed directly to the occurrence or severity of the crashes, but rather may reflect characteristics of the drivers or riders. This section presents the characteristics of the vehicles involved in the fatal single vehicle crashes. Comparisons between these vehicles and a control sample of vehicle are presented in the companion report, Estimation of risk factors for fatal singlevehicle crashes. 5.1 TYPES OF VEHICLES INVOLVED Almost 85% of the fatal single vehicle crashes involved a car (see Table 5.1). Motorcycles comprised about 8% and light commercial vehicles about 6% of vehicles in the study. The remaining 2% of vehicles were trucks. Table 5.1. Types of vehicles involved in the fatal single vehicle crashes. Type of vehicle Number of crashes Percent of crashes Car Motorcycle 10 8 Light commercial vehicle 7 6 Truck 3 2 Total Engine capacity was known for nine of the ten motorcycles in the study. Six of the nine motorcycles had an engine capacity of over 500 cc. None of the motorcycles with an engine capacity greater than 260 cc was ridden by a learner or probationary rider. The years of manufacture of the vehicles involved in the crashes ranged from 1956 to 1996 (see Table 5.2). Almost 20% of the vehicles involved in crashes were manufactured before 1978 and so were not required to comply with some of the current safety standards. The proportions of drivers who drove vehicles manufactured before 1978 appeared to increase with age but this effect was not statistically significant (13% under 25s, 21% 25 to 59s, 33% 60 and over, χ 2 (2)=3.3, p>.10). Seven vehicles (6%) were not currently registered. Four of these vehicles had drivers with BAC>.05 (one of whom was disqualified and one who had never obtained a licence). Another vehicle was driven by a driver whose licence was lapsed and another by a driver who had never obtained a licence. CHARACTERISTICS OF FATAL SINGLE VEHICLE CRASHES 23