Institute of Transport Studies, Monash University

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6-1-2010

Bus travel safety - A travel chain perspective Monica Berntman Anders Wretstrand Bengt Holmberg

Recommended Citation Berntman, M., Wretstrand, A., & Holmberg, B. (2010). Bus travel safety - A travel chain perspective. Paper delivered at the 12th International Conference on Mobility and Transport for Elderly and Disabled Persons (TRANSED 2010), held in Hong Kong on 2-4 June, 2010.

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BUS TRAVEL SAFETY – A TRAVEL CHAIN PERSPECTIVE

Berntman, Monica, Dep. of Technology and Society, Lund University, Lund, Sweden. [email protected] Wretstrand, Anders, Dep. of Technology and Society, Lund University, Lund, Sweden. [email protected] Holmberg, Bengt, Dep. of Technology and Society, Lund University, Lund, Sweden. [email protected]

SUMMARY The injury risk for bus passengers is low compared to car users. However, bus passengers also run the risk of sustaining injuries as vulnerable road users: as pedestrians or cyclists to and from the bus stop. Among vulnerable road users, seniors are a particularly important group. Hitherto, injury data have mainly been based on police-reported accidents. These accidents reveal bus occupant safety, rarely covering the whole travel chain. The aim of this study is therefore to incorporate all links in the travel chain, in order to better assess the risks in local and regional bus services. Instead of using only police data, both police- and hospital-registered injuries are collected, which will cover not only on-board injuries but also transport to and from the vehicle and during boarding and alighting. Four emergency departments in a southern Swedish county (Skåne) have been collecting data on bus-related injuries between 2006 and 2009. Follow-up studies (postal surveys) are made in order to assess longterm effects and medical costs. In order to assess incidence rates, injury data are complemented by using ongoing extensive travel surveys. The preliminary findings (with data from 2006 to 2008) from this study underscore the need for a holistic perspective when it comes to safety issues. A substantial number of bus-related injuries are sustained to and from the bus stops, and among these injuries older people are over-represented. These injuries are results of so-called single accidents, i.e. not directly involving external violence. Further results will target exposure, risk estimates, and societal costs for the group of elderly passengers as well as all user groups. Key Words: bus travel; older passengers; safety; injuries; travel chain

PURPOSE OF THE STUDY 1. Background Traffic safety is a major public health issue. It is estimated that more than 1 million people are killed on roads every year and up to 50 million more are injured. If current trends continue, the number of people killed and injured on the world’s roads will rise by more than 60% between 2000 and 2020 [Peden et al., 2004]. Risk comparisons for the EU show that the fatality risk for motorized two-wheelers is the highest of all modes, being on average 20 times higher than for car occupants. Also cycling and walking have on average a 7 to 9 times higher fatality risk per distance travelled than car travel. Road traffic collectively has the highest fatality risk per passenger km of all passenger transport modes. Rail and air travel are the safest modes per distance travelled, followed by bus. The passengers on trains, bus and planes within the EU have the lowest fatality risk per passenger km. For the average passenger trip in the EU, bus travel has a 10 times lower fatality risk than car travel; air travel within the EU for the average flight distance has about the same fatality risk per passenger km as train travel, and both are half as risky as travel by bus [ETSC, 2003]. Previous studies have hitherto been focusing on vehicle design, harm reduction by decreased crash probability (active safety) or minimization of consequences (passive safety) [Evans, 2002; Albertsson and Falkmer, 2005; Palacio et al., 2009]. As stated above, public transportation systems are relatively safe. Therefore, few accident or epidemiological studies focus on the injury risk incurred by PT passengers, and even less on the specific risk encountered by mobility impaired passengers [Wretstrand et al., 2010]. Most of the passenger incidents seem to have a very low severity, and thus been neglected and unreported. This is a major problem, as the occurrence of such incidents can be relatively high [Bylund et al., 2007], and thus have a high impact in terms of both objective and subjective safety, especially for older and disabled passengers. 2. Methodological challenges – non-collision events Significant methodological challenges confront traffic accident research, since official road traffic statistics generally only include vehicle-related injury events from policereported collisions. Previous research has underscored the significant difference in the coverage between hospital injury data and police injury data [Albertsson, 2005; Berntman, 2003; Bylund et al., 2007]. Of the approximately 400-450 annual road transport fatalities in Sweden, about 4% involve bus transit. This mode simultaneously accounts for about 7% of all passenger transport, largely in a traffic environment where many vulnerable road users reside [Arvelius and Wreiber, 2002]. Using public transport nevertheless means choosing a safe transport mode. However, if the whole travel chain is considered, accidents to and from terminals or stops must be incorporated. When that is done, the comparison reveals a less positive safety perspective. To date, there are few studies presenting such data. It could be estimated that bus trips are still twice as safe as car trips if the walk to/from a bus stop is added [Hydén, 2008]. However, as Vaa [1993] stated, the

door-to-door or travel chain perspective reveals quite alarming risk estimates. Comparing the risk of travelling door-to-door solely by bus to walking the same distance door-to-door points at a risk ratio of over 100:1 [ibid.]. Therefore, safety measures in bus transit must take the whole travel chain into consideration in order to achieve full effects, in particular with regard to the increasing number of elderly people as current or potential ridership. 3. Aim The aim of this study is to provide enhanced knowledge on bus transit safety. Instead of using police-reported data, hospital-registered injuries are collected, which will cover not only on-board injuries but also transport to and from the vehicle and during boarding and alighting. The results emanate from an ongoing study, of which we here have placed a specific focus on older passengers. Data from four southern Swedish hospitals are used, and preliminary results from the first three years are analyzed.

MATERIALS AND/OR METHODS 1. Data collection 1.1 STRADA The STRADA (Swedish Traffic Accident Data Acquisition) information system is a coordinated national registration of traffic accidents and traffic injuries run by the police and the health care authorities. This information system concerns only the road transport system. Since 2003 the police data cover the entire country, and currently more than 2/3 of hospitals with emergency units contribute to STRADA. The police and the hospitals involved collect data about the injured persons and the accident, at the accident site and in the emergency room, respectively, using different questionnaires. The data collected by the police include information about when, how and where the accident took place, traffic environment, speed limit, the circumstances of the accident, light and road surface conditions, passive safety systems used, and some detailed facts about the injured persons. Within the hospitals, supplementary data such as diagnosis classified according to ICD10, AIS/ISS codes, and care are collected. The Injury Severity Score (ISS) is an anatomical scoring system that provides an overall score for patients with multiple injuries. Each injury is assigned an Abbreviated Injury Scale (AIS) score and is allocated to one of six body regions (head, face, chest, abdomen, extremities, external). Only the highest AIS score in each body region is used. The three most severely injured body regions have their score squared and added together to produce the ISS score [Baker et al., 1974].

1.2 The current study Four hospital emergency departments participate in the current study: Malmö, Lund, Helsingborg and Kristianstad (all smaller or mid-sized cities in southern Sweden, county Skåne). They handle a designated questionnaire, specifically designed to track and

monitor bus-related injuries. This survey is henceforth called EQ. In addition to the EQ survey, the ongoing STRADA data collection called STRADA Police (STRADAp) and STRADA Health Care (STRADAs) provide additional information. The period will cover all injury events between 2006 and 2009, but at present data from 2009 remain to be analyzed. The EQ questionnaire contains issues regarding personal data and the accident (when, where, why, origin/destination, brief description of event, suggestions for improvement/avoidance etc.). 2. Analysis Data from the different sources (EQ, STRADAp, STRADAs) are matched, in order to provide a ―true‖ picture of all bus-related traffic accidents and injuries sustained. In order to estimate risk levels, data from travel surveys, transit authority statistics and national traffic statistics are used. (The latter analysis is not presented in this paper.) Both quantitative and qualitative data are used. The qualitative part emanates from patients’ descriptions of events and their suggestions for measurements and improvements.

RESULTS 1. Overview Official accident statistics, STRADAp, report 330 persons being injured while using buses. Due to a wider definition of ―using buses‖ in the hospital-based STRADAs register (since STRADAs also covers injury events during the whole travel chain), 1133 persons were found to have been injured in STRADAs. When matching STRADAp, STRADAs and EQ, a total of 1261 persons were found to have been injured. It is worth noticing that only a small number (3 %) have appeared in all three sources. A large number of persons injured are pedestrians moving to and from stops or terminals (38 %). Thirty-seven percent are bus passengers, 14 % car drivers or passengers (collisions with buses) and 8 % cyclists (to/from stops/terminals). In the official police report statistics (STRADAp) the dominant group is 15-24 years, while elderly people do not seem to be at risk while using buses. However, by using hospital data from the emergency rooms (STRADAs and EQ), the overall picture changes. Then, young people (0–24: 22%) as well as elderly people (65- : 31%) dominate. Each month in the target area, 35 people sustain bus-related injuries. Peaks occur during winter seasons. Sixty-three percent could be classified as single accidents, e.g. falls on pedestrian paths, inside the bus or while entering or exiting, and the rest due to collisions.

6% 20% 16%

11% 20%

0 - 14 15 - 24 25 - 44 45 - 64 65 - 74 75 -

27%

Figure 1: Age distribution among injured bus passengers. Older people account for 31% of the population of the injured (n=260).

24%

28% ice/snow uneven kerb object other unknown

5%

8% 19% 16%

Figure 2: Accident causes, surface condition. Injured pedestrians, EQ material, bus-related single accidents. (n=184).

2. Older passengers 2.1 Quantitative results Below, some results from analyses among the group of ―younger older people‖ (65 – 74 years) and ―older older people‖ (75+) are presented. These two groups account for 31% of the population of the injured (n=1260). Seventy-nine percent of the elderly are women, and 66% are 75 years or older (n=391). The gender differences are most likely due to different mobility patterns, modal split and health status. One important finding is that 86% of the accidents are so-called single accidents, whereas only 14% are related to collisions. Thus, single accidents are much more common among older people. The group of ―older older‖ people seems to be more prone to sustain single accident injuries (χ2, p