1 Introduction
In the UK, the ageing segment of the population is growing more rapidly than other age groups. The population of the current state pensionable age is expected to rise by 32% over the next 25 years from 11.8 million in 2008 to 15.6 million in 2033; and the number of people over 85 years is projected to more than double over the next 25 years from 1.3 million in 2008 to 3.3 million by 2033. The proportion of people aged 65 years and over is projected to increase from 16% in 2008 to 23% by 2033 [
1]. In Europe, the number of elderly people has tripled over the last 50 years and will more than triple again over the next 50 year period [
2]. The same trend is echoed in Canada, USA, Japan and the rest of the developed world. Meanwhile, the number of female elderly drivers has also increased dramatically in the last decade as more of these women started driving in later adulthood or became widowed, divorced or separated and did not have another driver available in the household [
3,
4]. This trend will continue in the future and lead to a more even gender distribution among elderly drivers than in the past. These statistics show that the proportion of elderly drivers, particularly female elderly drivers, as a part of the driving population will increase globally and therefore special, targeted care for this segment of drivers should be identified and addressed.
Research suggests that elderly drivers are less accurate in judging speed and distance and have more difficulty with multi-tasking [
5,
6]. Robertson and Vanlaar [
7] report that in Canada elderly drivers account for 16% of road deaths and 7.8% of injuries—the second largest behind the 15–24 years group. The same study highlights a rate of 15.7 deaths per 100,000 for the 65 years and over group compared to a rate of 24.7 deaths per 100,000 of the population in the 15–24 years group and 9.6 in the 24–65 years age group [
7]. Li et al. [
8] show that whilst the number of deaths per driver involved in crashes in the United States is lowest for those aged 16–19 years, it rises by almost fivefold for drivers aged over 80 years. However, in the same study, a measure of fragility can be found by comparing the number of road deaths per number of drivers involved in a crash (a measure of risk) and excessive crash involvement (i.e. drivers involved in crashes per vehicle-miles travelled (VMT)) showed that the rate of drivers involved in crashes per VMT was highest for those aged 16–19 years and falls rapidly until the 70–74 years age group when it rises again. Thus, although the under 24 years age group has a larger crash risk than the over 65 years age group, the over 65 group drives comparatively fewer miles than the under 24 age group, but are more likely to suffer more serious or even fatal injuries, thereby having a higher measure of fragility and vulnerability. Furthermore, elderly drivers also have a problem with maintaining a constant vehicle speed [
9].
McGwin et al., [
10] showed that for drivers aged 65 years and older, the at-fault crash rate was 2.1 times higher for drivers who had been involved in a crash in the previous 4 years compared to those who had not, herefore an elderly person who has had a recent crash is more likely to have another one. This study also determined that at-fault drivers more often rated their driving as average or worse compared to not at-fault drivers. Habitual hazardous and critical errors highlighted in an Australian on-road driving assessment study of elderly drivers (aged between 60–86 years) showed that failing to check the blind spot, observe intersections and make critical observations (i.e. ‘failure to observe critical features of the driving environment that compromised safety including pedestrians on crossings, vehicles entering the flow of traffic, critical traffic signs or road markings’) were in the top four reported errors by the assessors [
11]. Physical intervention by the instructors resulting from critical driving errors were primarily committed by drivers negotiating intersections, along with failures in observations, gap selection and vehicle positioning [
11].
Breker et al. [
3] considered that elderly drivers are not often accident prone for the following reasons: they have a lower proportion of alcohol use when driving, use restraints more frequently and do not show signs of losing control over the vehicle in curves and straight sections. However, they are often involved in accidents at an intersection where fast information processing and quick reactions are required. AGILE (Aged people Integration, mobility, safety and quality of Life Enhancement through driving), a project funded by the European Commission Research Programme ‘Quality of Life’ Key Action ‘The Ageing Population’, conducted a survey with drivers in three age groups (55–64, 65–74, 75+) in 2001. The results indicate that the older the age group the person is in, the more often he/she is the following: the main driver in the household, legally responsible for accidents occurring recently, drives fewer miles monthly and is less open to external support such as special training and consultation courses [
3]. Gender differences are also found in driving behaviour. Compared to male elderly drivers, female elderly drivers tend to drive fewer mileages; have less driving experience both quantitatively and qualitatively; and are less often involved in or responsible for accidents [
3,
4].
However, driving plays an important and essential role in maintaining elderly people’s mobility and independent living, enabling them to participate in their usual social activities and carry out practical day-to-day needs [
7,
12‐
14]. From a psychological perspective, driving makes them feel younger, more confident and independent, whilst mobility increases their feeling of control, self-esteem, protection and prestige, enhances their status and helps them participate in work, education or social events and develop cognitive skills. Asking for lifts and the use of public transport could be alternatives to driving. However, UK Economic and Social Research Council (ESRC) research found that older people are exceedingly reluctant to ask family members or friends for lifts, even to hospital or doctor’s appointments, unless some kind of reciprocal relationship is involved [
15]. Gilhooly [
15], AgeUK [
16] and Brake [
17‐
19] indicate that barriers to using public transport may exist, such as being physically inaccessible; a lack of covered waiting areas and toilets; the perception of being unsafe and unreliable, expensive and inconvenient; whilst very often services such as hospitals and cheaper out of town shopping centres are poorly served by public transport. In addition, many elderly people are not able to walk the required distance, stand for a long time or have the overall physical endurance to use public transport. Given that both car ownership and driving appear to be related to a higher quality of life, giving up driving can lead to reduced mobility, lack of freedom, loss of independence, unmet social and aesthetic needs, lower quality of life and eventually depression and isolation [
12,
15].
This paper reviews factors involved in the functional decline of elderly drivers which is well-documented as the main cause of reduced driving ability. It goes on to assess the feedback and support capabilities of IVSs with the potential to assist elderly people to drive safely for longer and maintain their quality of life. Lastly, it describes a newly funded project, Social inclusion through Digital Economy (SiDE), which will demonstrate an innovative application of driving simulator technology to test and evaluate the impact on elderly drivers of emerging IVSs.
2 Functional decline of elderly drivers
Age-related functional decline in physical health (especially mobility, sight and hearing) and mental health can impact on driving ability and lead to misjudgements and errors whilst driving. Elderly people suffering from a decline in physical health—such as stiffer muscles, limited neck and upper body rotation and loss of upper limb strength—can affect their ability to move and operate the car safely [
7,
20,
21]. People suffering from a decline in visual health such as blurred vision and photophobia can experience problems with distance vision and sensitivity to light and glare [
20,
22,
23]. Age-related functional decline can also be caused by other medical issues including a stroke, heart disease or medications prescribed to treat a specific ailment or other illness [
10,
12,
20,
22,
24]. People suffering from a decline in mental health, such as loss of confidence, memory, concentration and capability to process information, can be more susceptible to distraction, find it difficult to perform multi-tasking and difficult to understand road signs and travel information displayed on the dashboard [
12,
20,
22,
25].
In order to compensate for functional decline, elderly drivers tend to drive less: this is possible as they no longer need to commute and travel to work after retirement [
12,
26‐
28]. They deliberately avoid driving at night, in poor road conditions or other risky situations and places such as wet roads, rush hours, heavy traffic, unfamiliar roads and localities, bad weather or damaged roads: these practices all contribute to a reduction in the annual mileage driven [
27,
29,
30]. They display a coping mechanism for easing the driving tasks by creating more time. This specific strategy allows them to cope with a reduced capability to process information and allows the task to be completed consciously rather than reactively [
5,
31,
32]. This is usually achieved by slowing down before a manoeuvre (such as turning to cross a traffic lane). However, in certain situations, such as entering a high speed motorway, slowing down is not an effective coping mechanism and indeed it may contribute to increasing the risk of an accident. This risky behaviour can be compounded further by physical deficiencies such as reduced neck rotation which can commonly lead to a loss in ability to check the blind spot [
11]. They also tend to avoid right turns by taking routes that require left turns or routes where right turns have green-arrow signals [
33‐
35].
4 Use of a driving simulator to evaluate the impact of in-vehicle systems on elderly drivers
The history of driving simulators can be traced back to the 1920s when simulation was first used to evaluate the skill and competence of public transport operators [
58]. Since then, driving simulators have been used to investigate the parameters that govern driver choice and behaviour, driver training and evaluation of vehicle design and technologies. It was pointed out by Yang et al. [
58] and Lee et al. [
59] that driving simulators give researchers full control of the situational and environmental variables. Also, Breker et al. [
60] report that simulation makes it possible to conduct tests in new ways that cannot be realised in real traffic environments. This means that they can conduct observation and evaluation of driver performance and behaviour in relation to the impacts of hypothetical road elements or traffic events. This means that they can avoid potentially hazardous on-road driving conditions and accompanying legal restrictions that may be caused by experiments. It is also a cost-effective alternative to on-road driving tests. The main concern regarding research using driving simulators is the validity of the results. In order to bring high fidelity user experience to the study subjects, it is essential to provide the subjects with the same sensory cues that they experience in real world driving. However, this was not possible in the past which led to misinterpretation of the signals between the eye and the inner ear. Elderly subjects often suffered motion sickness and had to terminate the experiment early. Furthermore, an older person’s ability to act in an unfamiliar technological environment might influence driving performance in the simulator as moderating variable [
60]. With the development of motion-cueing algorithms, the current generation of driving simulators (often in a form of the front half or all of a car) are supported by the use of a sophisticated and interactive motion-platform. This platform, which is integrated underneath the driving simulator, is able to provide an immediate understanding of the motion of the vehicle in the simulated world and a valid duplication of the real world driving experience.
Driving simulator technology is being applied in the Social inclusion through Digital Economy (SiDE) project. This has been funded by the Research Councils’ UK Digital Economy Programme for 5 years from October 2009. Based at Newcastle University, SiDE will address four fields where digital technologies and the building of a truly inclusive digital economy could deliver major social benefits: Connected Home and Community, Accessibility; Inclusive Transport Services; and Creative Industries.
One of the key studies covered under Inclusive Transport Services is to evaluate whether IVSs underpinned by emerging technologies can assist elderly drivers to drive safely for longer. To understand elderly drivers’ behaviour in response to such IVSs, the SiDE project intends to establish driver awareness of their driving capability—and therefore their vulnerability as road users—which can then be compared with their actual functional ability at a later stage. This is different from the AGILE project which focused on establishing an aetiological classification of ageing-related illnesses associated with driving and accidents and gathering knowledge of driver assessment, driver training and traffic safety.
IVSs will then be tested using a driving simulator (as described above) equipped with a suite of technologies, including in-vehicle sensors (located on the pedals and steering wheel), multiple cameras and projectors, eye tracking and head movement systems and distributed ad-hoc wireless networks. As seen in Section
3, each IVS has a different set of capabilities which will be tested and evaluated individually as well as the whole system. These capabilities will be analysed according to the information that is being delivered (e.g. navigation instructions, lane departure, headway), the reactions made by the subjects (such as braking, accelerating, entering an intersection or high speed traffic) and the degree of personalisation and tolerance of visual load that can be made by the user. After each IVS has been evaluated, there will be a comparative evaluation of all the systems.
Individual driver performance and attitudes to the IVSs will be measured before and after the implementation of each IVS into the driving simulator and its environment. This will permit a sound understanding of the impacts on individual elderly drivers and the scope for adopting these systems. The output of this study will identify the most appropriate combinations of in-vehicle capabilities; the propensity for elderly drivers to adopt these systems; and it will recommend ways of increasing the awareness of elderly drivers about their vulnerability as road users and how it may be overcome using IVSs. The research will also help to identify personalised training needs for individual elderly drivers and to enhance the elderly drivers’ understanding of the other drivers’ driving behaviour and inform the development of new rules and traffic signs.
5 Conclusion
Elderly drivers are fragile and vulnerable on the road and do not represent an excessive risk or threat to other road users. They are more likely to hurt themselves than to put others at risk. Meanwhile, some of they are more likely to be involved in traffic accidents, be at fault, and are over-represented in traffic fatalities due to age-related functional decline. Also, the ageing population is growing fast worldwide, which is likely to be accompanied by a rise in age related accidents with an inevitable social and monetary cost for society. Neglecting their need for safe driving will lead to a decrease in their quality of life, loss of independence and potentially a high rate of clinical depression.
A review of IVSs suggests that providing feedback and support to elderly drivers has the potential to enhance their safety on the road and benefit the transport network as a whole. Driver feedback offers information on elderly drivers’ driving performance and helps them be aware of the misjudgements or driving errors being made. Driver support provides elderly drivers with timely and constructive advice, alerts, warnings or even active interventions which take over the activity from the driver to avoid accidents or reduce the seriousness of the accidents. Driver feedback and support can be delivered either in-vehicle using head-up displays or off-vehicle using a home computer or other personal mobile devices.
A newly funded research project, Social inclusion through Digital Economy (SiDE) will evaluate the impact of IVSs on elderly drivers’ driving performance to ascertain whether such systems can assist elderly drivers to drive safely for longer. SiDE will establish elderly drivers’ vulnerability as road users based on their awareness of functional decline, and will test a suite of selected IVSs using a driving simulator. It is anticipated that the SiDE project will deliver a sound understanding of the impacts of different systems on elderly drivers, the scope for adopting individual systems or combinations of systems and the individual training needs for safe driving for older drivers. It will also help the elderly drivers’ understanding of the other drivers’ driving behaviour and inform the development of new rules and traffic signs.