ITARDA 24th Work Shop Report

2021
24th Presentation Session for Traffic Accident Investigations, Analysis, and Research

Unsafe Behavioral Tendencies During Driving and Accident Prevention from theViewpoint of Driver Behavior Formation in Older Adults

Hanae Kosuge
Special Researcher, Research Division

ITARDA 24th Work Shop Report

1. Background of research and purpose
Despite having a decreasing overall population, Japan's population of those aged 65 and older is increasing1), as
are the number of license holders aged 75 and older2). In super-aging societies such as that of Japan, serious accidentscaused by older adult drivers are also occurring, requiring the need for more effective measures aimed at older adultdrivers.
The Institute for Traffic Accident Research and Data Analysis (hereinafter, ITARDA) conducted joint research3)
in collaboration with the Driver’s License Department of the Chiba Prefectural Police Headquarters aimed atestablishing measures for older adult drivers. As part of this research, they collected data regarding approximately
9,000 participants of driver training courses for older adults (hereinafter, "the training") held in Chiba Prefecture,including data such as "Driving Frequency Questionnaires"4) (hereinafter, "questionnaires") and "Driving Behavior
Observation Records"5) (hereinafter, "observation records"). Afterwards, analysis was performed on driving
behaviors deemed as unsafe by evaluators during actual driving performed by older adult drivers, such as driving
behaviors evaluated as "dangerous" or "requiring attention"6). However, reasons as to why such unsafe driving
behaviors are formed in older adults was not considered.
In preventing accidents by older adult drivers, it is important to consider accident prevention measures aimed atolder adult drivers themselves in order to help them avoid unsafe behavior and drive safely. For that purpose,
research aimed at organizing approaches to systematic accident prevention (Fig. 2) and dependent upon the contexts
in which unsafe behavior by older adult drivers is formed is necessary. By gaining an empirical understanding of
unsafe behavioral tendencies exhibited by older adult drivers and asking why such unsafe behaviors are formed,
this research considers what kinds of support for safe driving, such as "educational support" and "technical support",
are appropriate for preventing such unsafe behavior before it occurs. In other words, there is a need for systematic
research that sequentially studies methods of supporting safe driving in terms of expressed unsafe behavioral
tendencies and responses therefor by focusing on the contexts in which unsafe behavior is formed.
In this research, using unsafe behavioral tendencies observed during actual vehicle driving by older adult drivers
as revealed in previous studies3)6) in which unsafe behavior data from approximately 5,400 individuals was used,approaches of supporting safe driving were considered based on the contexts in which unsafe behaviors were formed
and from the perspective of psychology. Specifically, an attempt was made to systematically organize what unsafe
behaviors are affected by aging-related changes and driving experience by assuming the context in which older
adult drivers form unsafe behaviors and by associating those contexts with unsafe behavioral tendencies andmeasures for supporting safe driving (Fig. 2).
In this manuscript, unsafe behavior is defined as "older adult driving behavior evaluated by the training instructor
as being "dangerous", "requiring attention", "inappropriate", etc."1

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2. Method
2-1. Analysis data
As subjects for this research, participants intraining performed in Chiba Prefecture between
September 2018 and September 2019 were used,with the analysis data consisting of a database (withinformation on 8,928 individuals) which matchedtraining data made up of diagnosis forms andquestionnaires.
2-2. Unsafe behavior data
During the on-road driving portion of the training,Fig. 1 - Driving Behavior Diagnosis Formany time driving school instructors observed orevaluated driving as being "dangerous", "requiring attention", or "inappropriate", they would make entries such as"disregarding traffic signal" or "failure to make safety check" into the remarks column for each item in the diagnosis
form (Fig. 1) as they saw fit. During this research, words or phrases related to unsafe behavior were extracted fromthis descriptive data to generate unique detailed items, with detailed items used only by specific driving schools
being excluded. In the end, there were 78 detailed items for unsafe behavior in the unsafe behavior data (binary dataconsisting of Applicable: 1/Not applicable: 0).

3. Unsafe behavioral tendencies in older adult drivers
3-1. Consolidation of detailed items for unsafe behavior by grouping
In order to consolidate the 78 detailed items for unsafe behavior (N = 5,477), the Euclidean distance wascalculated from the tetrachoric correlation coefficient between all detailed items, hierarchical cluster analysis ofvariable classification was performed using Ward's method, after which a tree diagram was created from the obtained
matrix. Clusters were cut at a distance obtained from the four factors6) obtained via factor analysis using the samedata and a theoretical interpretation of driving behavior. In this manner, unsafe behaviors by older adult drivers wereconsolidated into seven types by individually grouping detailed items most resembling corresponding patterns forbehavior-related detailed items in order (see prior research3)6) for details on the analysis performed in 3-1).
3-2. Understanding how unsafe behavioral tendencies are classified
In order to understand the each of the unsafe behavioral (cluster) tendencies summarized in 3-1, the ratio of thoseindividuals who corresponded to even one of the behavior-related detailed items (some individuals corresponded tomultiple items) that make up each cluster was calculated. Correspondence analysis was conducted on therelationships between questions on the questionnaire (regarding "driving frequency", "vehicle type" and"transmission type (AT/MT)") and each cluster on the premise that the unsafe behaviors by older adult drivers areformed in response to individual driving experiences (unsafe driving knowledge and schema). In addition, a chisquare test was performed on the relationship between the "age" entered into the questionnaire, as well as "resultsof the cognitive function test7)", and each cluster on the premise that unsafe behavior is formed in response to agingrelated changes (decline in memory, etc.).

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From the results of the above categorical data analysis performed for each cluster, tendencies characterized as
unsafe behavior were organized and named based on prior findings. Unsafe behavioral tendencies include (1) "Selfstyled driving strategies" consisting of 10 detailed items, (2) "Performing of inappropriate actions" consisting of 6
detailed items, (3) "Automation of habitual actions" consisting of 9 detailed items, (4) "Failure to grasp trafficsituations" consisting of 9 detailed items, (5) "Failure to perform necessary actions/procedures" consisting of 23
detailed items, (6) "Failure to perform line-of-sight operation" consisting of 9 detailed items, and (7) "Delayed orforgotten reactions" consisting of 12 detailed items (see prior research3)6) for details on the analysis performed in 32).

4. Unsafe behavioral tendencies and accident prevention as seen from older adult driver behavior formation
This manuscript considered what effects past driving experience and aging have on the formation of unsafe
behaviors by older adult drivers using psychological knowledge. This was done by first assuming three contexts forthe formation of unsafe behavior. The assumed three contexts were then correlated with seven unsafe behavioraltendencies before organizing the contexts for behavior formation to determine how the unsafe behavioral tendencies
organized in 3-2 are formed, before considering approaches to accident prevention that help older adult drivers
avoid unsafe behavior while instead conducting safe behavior.
4-1. Contexts for the formation of unsafe behavior by older adult drivers
Although driving is performed using skills acquired during past driving experiences, these driving skill arethought to be hierarchical8). It is thought that vehicle operation skills (positioned at the bottom under "Context ofbehavior formation" in Fig. 2) are first acquired, after which skills for adapting to traffic situations (positioned in
the middle under "Context of behavior formation" in Fig. 2) are acquired. From this, it is thought that unsafe
behavior by older adult drivers is related to problems with these two driving skills.
Also, driving skills are behaviors formed through learning, with an individual's driving style being createdthrough accumulated driving experience. From this, it is thought that unsafe behavior by older adult drivers is also
related to problems with driving styles acquired through past driving experience.
Safe driving support
Context of behavior formation

Regular driving checks
Relearning of correct
driving methods

Unsafe behavioral tendency
Self-styled driving strategies

Established unsafe
driving styles

Performing of inappropriate
actions
Automation of habitual actions

Early-stage detection of
impaired skills
Periodic skills training
Vehicle or environmental
technical support

Impaired skills foradapting to traffic situations

Impaired mental and physicalfunctions that support vehicle
operation skills

Failure to grasp traffic situations
Failure to perform necessary
actions/procedures
Failure to perform line-of-sight
operation
Delayed or forgotten reactions

Fig. 2 - Unsafe behavioral tendencies and support for safe driving depending on context of behavior formation

Furthermore, driving is supported by various mental and physical functions such as cognitive function, sensory
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ITARDA 24th Work Shop Reportfunction, and muscular strength, which decline with age, although differences exist between individuals. For thisreason, it can also be assumed that problems with mental and physical functions that decline with age and which
may have an effect on driving skills are a factor in unsafe behavior by older adult drivers.
As seen above, two driving skills, driving style, and three types of aging-related changes are to be consideredfactors in the formation of unsafe behavior by older adult drivers, for which the three contexts of behavior formationin Fig. 2 are assumed.
From the viewpoint of driving skills, the skilled behavior at the basic level of moving a vehicle is thought to beclosely connected to mental and physical functions, for which "impaired mental and physical functions that support
vehicle operation skills (Fig. 2)" was assumed to be the context in which unsafe behavior is formed. In addition, theskilled behavior at the level of adapting to traffic situations while driving is thought to not only be influenced bydecreased cognitive function, which is required for grasping such situations, but also by impaired driving skills
caused by decreased driving frequencies, for which "impaired skills for adapting to traffic situations (Fig. 2)" wasassumed to be the context for the formation of unsafe behavior by older adult drivers. Furthermore, from theviewpoint of driving style, when considering individual driving experience (unsafe driving knowledge and ideas),
it was assumed that unsafe behavior is formed due to "established unsafe driving styles (Fig. 2)" that were
established over many years of driving experience.
4-2. Unsafe behavior due to established unsafe driving styles and support for safe driving
As found in this research, driving which exhibits “self-styled driving strategies” in which behavioral habits
acquired through daily driving are strongly expressed, the “performing of inappropriate actions” due to appropriate
knowledge, such as how to proceed through intersections, not having been established, and the “automation ofhabitual actions” due to manners of operational behavior or unique cognition resulting from having driven LL-sized
vehicles, etc., are assumed to be influenced by strongly organized and inappropriate driving styles acquired over thecourse of daily driving experience and are considered to be unsafe behavior representative of a person's own drivingstyle.
These unsafe behaviors are thought to be formed with "established unsafe driving styles (Fig. 2)" as a context,
and it is thought that driving risks such as these can be reduced by re-learning correct and safe driving methods at astage where such behavior can be corrected. Accordingly, a conceivable approach for supporting safe driving is tocheck drivers daily driving behavior and have them acquire correct driving behavior and relearn said methods before
unsafe behavior becomes set in place from middle age.
4-3. Unsafe behavior due to impaired skills for adapting to traffic situations and support for safe driving
Driving which exhibits a “failure to grasp traffic situations” due to the effects of decreased driving frequency, ora “failure to perform necessary actions/procedures” in which dangerous behavior appears during general driving
due to multiple effects such as decreased cognitive function or decreased driving frequency, is thought to be caused
by problems with driving knowledge (schema) used for responding to situations and acquired through learning, ordue to problems with skills for adapting to traffic situations, and is assumed to be unsafe behavior at the level ofadapting to traffic situations.
These types of unsafe behavior are thought to be formed with "impaired skills for adapting to traffic situations
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ITARDA 24th Work Shop Report(Fig. 2)" as a context, and because driving that had been possible until individuals reach an advanced age isinfluenced by factors such as decreased driving frequencies and decreased cognitive function, it is thought that thesetypes of unsafe behavior are an expression of behaviors that are no longer possible. Accordingly, support for safe
driving could include periodic skill training for drivers with decreased driving frequencies in order to prevent
decreases in driving skills, or a scheme in which checks for decreased cognitive function and driving frequency are
performed to enable early-stage detection of unsafe behavior related to an inability to grasp traffic situations, a skill
which is likely to become impaired, and to provide training therefor. Furthermore, training on driving methods thatsuit an individual's current abilities is also necessary.
4-4. Unsafe behavior due to impaired mental and physical functions that support vehicle operation skills andsupport for safe driving
Driving which exhibits a “failure to perform line-of-sight operation” suggestive of decreased cognitive function
or an aging-related decline in eye movement ability, or which exhibits “delayed or forgotten reactions” suggestiveof effects to memory when performing simple actions or operations and caused by decreases in reaction speed orattention due to age, is that in which an aging-related decline in a driver’s fundamental ability to operate a vehicle
and perform actions can be observed, and is assumed to be unsafe behavior at the level of vehicle operation.
These types of unsafe behaviors are thought to be formed with "impaired mental and physical functions that
support vehicle operation skills (Fig. 2)" as a context, and it is thought that unsafe behavior in current traffic
environments results from aging-related barriers that arise and limit drivers from retaining the abilities required fordriving. As individuals age, their reaction slows and prevents them from moving their bodies or vehicles smoothly.
To enable drivers to drive in a manner suitable for traffic environments despite such circumstances, it is conceivablethat technical support could be provided in the form of vehicle-mounted driver-assist technology or by altering roadenvironments in a manner that facilitates driving for older adults.

5. Conclusion
It is not the case that all older adult drivers commit pedal misapplication. Unsafe behavior is expressed in various
forms and with varying characteristics, such as behavior at the operation level and behavior at the level of adapting
to traffic situations. Furthermore, unsafe behaviors by older adult drivers are not uniformly formed solely due toaging-related declines in mental and physical functions. When considering skilled behaviors that have been learned
and aging-related changes, the behaviors of older adult drivers were observed as being formed with contexts suchas impaired driving skills due to decreases in driving frequency and cognitive function, as well as established unsafe
driving styles acquired through past driving experience.
In order to enable older adult drivers to continue driving safely, unsafe driving behavior must be prevented inadvance to prevent accidents. In the future, services or schemes for providing appropriate driving support, either inthe form of early-stage educational support or technical support, and depending on the contexts in which the various
types of unsafe behavior exhibited by each and every driver are formed, will be required.

5ITARDA 24th Work Shop Report<Acknowledgments> This research was based on data used in the joint research program “2019 Investigative
Research of Drivers Utilizing Questionnaires Regarding Driving Frequency, etc.” performed in collaboration with
the Driver’s License Headquarters of the Traffic Department at the Chiba Prefectural Police Headquarters. A portionof this research was presented at the 62nd Infrastructure Planning and Management Conference held in the fall of2020, as well as published in the report "Research Study on Older Adult Drivers Using Questionnaires Regarding
Driving Frequency, Etc." in 2021. I would like to extend my sincere thanks to all related parties who provided theircooperation with this research at the Chiba Prefectural Designated Driving School Association, Chiba Prefecture's
designated driving schools, the Driver’s License Headquarters of the Traffic Department at the Chiba Prefectural
Police Headquarters, and the Heiwabashi Motor School.
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