Abstract
BACKGROUND:
Drivers’ drowsiness is a significant issue globally known as a contributing factor to crashes in various transportation operations. Although there is evidence that suburban bus drivers experience drowsy driving, most previous studies are quantitative, which means that drivers experiencing drowsiness have not had the opportunity to explain their direct views and thoughts.
OBJECTIVES:
This qualitative exploratory study subjectively investigates the contextual factors influencing fatigue among suburban bus drivers.
METHODS:
Collecting data was conducted through 14 in-depth interviews with suburban bus drivers working in Tehran province’s transportation system, Iran. The interview recording was transcribed by the research team and entered into the qualitative data analysis software. Two independent coders with qualitative content analysis and thematic analysis approach analyzed transcripts.
RESULTS:
Four themes emerged, including human factors (with categories of individual characteristic and lifestyle), vehicle factors (with categories of design and performance), job factors (with categories of task requirement, quantity and quality of sleep, and circadian rhythm,) and environmental factors (with categories of the physical and economic environment). We found a more significant number of codes and categories and thus more contextual factors associated with job factors. The participants emphasized the importance of sleep deprivation, long driving hours, and even time of the day as factors influencing fatigue.
CONCLUSIONS:
The study results can provide beneficial information for both ergonomists and car manufacturers in developing more accurate fatigue detection models and effective educational and technical interventions to maintain road user’s health and reduce road accidents and mortality rates due to drowsiness.
Introduction
Road accidents are among the most globally common problems and are currently at a significantly high level in Iran. According to the statistics of the legal medicine organization issued in 2014, 16,872 deaths and 304,485 cases of injuries caused by traffic accidents happened in Iran [1]. Upward trends in accidents show that by 2030, accidents will become the fourth leading cause of Disability-Adjusted Life Year and the seventh global cause of mortality [2]. The DALY index is one of the indicators used by the World Health Organization to estimate the lost years of life due to illness, premature death, or physical and mental disability over a specified period of time, in addition to it estimates the economic consequences of premature death and injuries caused by traffic accidents and quantifies the burden of traffic accidents from mortality and disability.
Many factors are involved in the occurrence of traffic accidents. In 1968, William Haddon introduced the famous model of causes of traffic accidents called the “Haddon matrix model,” consisting of three interactive factors: human, vehicle, and road/environment [3]. Subsequent studies have shown that the human factor is the most leading cause of traffic accidents among other factors. Approximately 90% of all accidents are based on human error [4, 5], and about 20–30% are attributed to the drivers’ drowsiness [6]. This situation is even worse in developing countries, such as Iran [7].
Suburban bus drivers in comparison with other drivers, experience more occupational risk factors for drowsy driving, such as sedentary working, long driving hours, requiring constant attention and vigilance, and irregular shifts [8–10].
The available research has indicated that about 45% of Swedish bus drivers have to cope with drowsiness at least 2–4 times each month during driving, and 19% of drivers make a tremendous effort to stay awake at least 2–3 times per week [10]. Other findings for London bus drivers reported that 36% have to cope with drowsiness while driving at least 2–4 times per month, and more than 20% of drivers try to stay awake at least 2–3 times a week [11]. A questionnaire survey results showed that factors affecting the incidence of collisions and near-misses, influenced by drowsy drivers, stayed steady in driving hours. The drivers continued driving even when there were some adverse situations such as sick feelings, reporting an impaired physical condition, lack of adequate sleep, long working hours, and unbalanced nutrition [12, 13]. Nearly 74% of bus drivers in Peru reported drowsy driving, and 25% felt sleepy [14]. Teff has shown that 27% of drivers have experienced difficulty keeping their eyes open within the past month, and 41% of drivers admitted falling asleep while driving at least once in their lifetime [15].
On the other hand, any impairment in the drivers’ operational status (e.g., physical and psychological condition) can have undesirable consequences for passengers and bus operating companies [16, 17]. Recognizing that the bus is one of the most popular modes of public transport worldwide, which will continue working in the future, makes it essential to consider the drivers’ impaired function.
Although various quantitative studies have been conducted in this field, the fundamental reason for fatigue among professional drivers has not been well investigated due to the lack of qualitative research and sufficient knowledge of reporting fatigue. Qualitative and participatory methods, such as interviewing, are well established in the driving community because they describe and explain social contexts and processes around unexplainable events in the quantitative analysis [18].
Besides, understanding stakeholders’ viewpoints on the causes and possible solutions to accidents increases the probability of supportive, sustainable, and effective interventions.
In road accidents due to the significant contribution of human factors, independently or in interaction with other factors, it is necessary to understand drivers’ experiences to find out the reasons of drowsy driving and discover essential strategies to prevent this behavior.
This study investigates the perception and experience of professional drivers and their concerns about the contextual factors affecting drowsiness while driving. The study results can provide valuable information and better insight for both ergonomists and car manufacturers into developing more accurate fatigue prediction models and technical or educational interventions to reduce the risk of drowsiness and road accidents.
Methods
A qualitative methodology was adopted to obtain the general perception of drivers about the causes and effects of fatigue while driving in Iran. The method provides an initial exploration for ongoing studies on the driving situation in Iran. It allows researchers to investigate critical fatigue-related issues determined by findings from the developed world studies even without restraining how these issues are framed. Further, it provides a period for participants to talk about newel issues unique to the developing countries that have not been predicted in the developed world researches. Thematic analysis was employed to identify unpredictable insights within the data correctly.
Ethics
The study was approved by The Ethics Committee of Tehran University of Medical Sciences (Approval code: IR.TUMS.SPH.REC.2020.131). Possible participants were provided with information about the aims and procedure of the research, which included confidentiality and anonymity of their contribution. All participants expressed their informed consent before participating in the study, and all protocols were adjusted following the Helsinki Declaration to consider the priority of human subjects’ well-being over the interests of science and society.
Trustworthiness
As suggested by Granheim and Lundman, reliability reporting is one of the essential points in qualitative researches [19]. Credibility, dependability, and transferability were considered to determine our data’s reliability, trustworthiness, and authenticity. Credibility was accomplished by asking participants to verify whether the interview texts and the extracted codes are accurate (and revising as necessary).
The analysis process was validated by reviewing the codes and categories by eight appropriate ergonomics and occupational health experts. Dependability was achieved using a semi-structured interview guide in all interviews and strong coding and classification rules during the data analysis process.
The drivers were ensured that their names would be kept confidential. During the study, the participants’ confidentiality and freedom were considered (to participate in research or leave it). They also gave oral consents for recording the audio.
Finally, data collection continued until the data saturation i.e., when the researcher could not achieve a new code [20]. The quotes used in this manuscript were translated to English in the article draft. Although they are not verbatim quotes, they can introduce the fundamental concept.
Participants
Fourteen bus drivers were selected from the list of suburban bus drivers who had at least five years of working experience in Tehran province’s transportation system and had previously applied to Khajeh Nasir al-Din Toosi University to participate in qualification courses and receive a professional driving license. After selecting the eligible people, an interview was arranged by calling them.
Research team
Two of the authors, a Ph.D. student, and a professor researcher, interviewed the drivers and took notes throughout the interviews. All of the interviewers were pre-trained and had experience in qualitative research methods. A graduate and a Ph.D. student performed the interview coding.
Procedure
Driver fatigue is a multidimensional construct. It has been broadly used to indicate a wide range of driver states and has different causal mechanisms. Based on May and Baldwin model, driver fatigue can be subcategorized into sleep-related (SR) and task-related (TR) fatigue. Sleep-related (SR) fatigue, which negatively affects most intervention strategies, results from accumulated sleep debt, prolonged circadian rhythm, and hemostatic pressure. Conversely, task-related (TR) fatigue is caused by a lack of rest time and overloaded cognitive demands [21].
In this study, driver fatigue is defined as psychological and mental impairment, potentially reducing the capacity for paying attention to driving tasks and optimal performance [22]. At the beginning of each interview, the concept of ‘fatigue’ was explained to ensure consistent understanding amongst the participants. Also, in literature, fatigue, sleepiness, and drowsiness are often used synonymously. However, fatigue is frequently used within the transport industry, and therefore, it is predominately employed here [23].
Before conducting the interview, the literature related to the contextual factors affecting driver fatigue was reviewed, and the interview protocol was designed. The interview protocol consisted of several general questions related to the study’s purpose and some other in-depth and exploratory questions based on the answers to ensure that all topics were covered. The discussed topics and example questions are shown in Table 1.
Overview on interview topics
Overview on interview topics
The interview data were analyzed by the coders using thematic analysis [24]. The analysis was performed in three phases: 1) initial analysis, 2) focused coding, and 3) thematic coding. Initially, the primary codes were created and defined; for example, the question “Who is prone to fatigue during driving?” became the “Individual characteristics” code. Responses to the previous question, and parts of the text related to the question, were placed in the “Individual condition” code. This process was completed for all text and codes in the initial coding phase. Focused coding was conducted iteratively with the initial coding phase. It was utilized for responding to unfitted codes, which resulted in creating sub-codes under existing initial codes. At this stage, the existing codes were organized based on the identified patterns and similarities. An example of focused coding for the “individual characteristics” code is creating sub-codes including ‘Age,’ ‘Overweight,’ ‘Pain and disease’ and ‘Professional driving experience.’ Finally, the thematic coding process was performed to make connections between themes and concepts amongst predefined codes. The extracted codes were managed by the MAXQDA Analytics Pro version 10 data organizing software [25].
Results
The mean and standard deviation of the participants’ age was equal to 50.85±7.24. All drivers in the study were male and married. Table 2 shows the demographic characteristics of the study population.
Demographic characteristics of the studied drivers
Demographic characteristics of the studied drivers
All of the participants believed that fatigue is a critical issue amongst suburban bus drivers. Although some participants stated that they do not fall asleep while driving, they mentioned accident samples from other colleagues.
Drivers were aware of the consequences of driving when fatigued. According to them, fatigue will lead to loss of concentration, slower reaction time, improper planning, and risky driving behavior.
The thematic analysis resulted in 20 subcategories done independently by two researchers. Then, these were agreed upon and stored jointly into eight categories and four themes. The themes were including human, vehicle, job, and environmental factors. Table 3 presents the themes, categories, subcategories, and frequency of each subtheme, and in the following, we will explain them.
Description of the theme, categories, and subcategories that emerged during data analysis and their number
The majority of participants emphasized the role of the driver in the occurrence of road accidents. Qualitative content analysis of interview reports resulted in two categories: 1) Individual characteristics and 2) Lifestyle.
Individual characteristics
According to the reports, a person’s characteristics, such as obesity, illness, age, driving experience, and marital status, are related to accidents caused by fatigue and drowsiness. From the participants’ point of view, overweight and mental or physical illnesses are associated with an increased possibility of drowsy driving. Although different reports mentioned the effects of age on drowsy driving, some drivers believed that it does not increase the risks, while others stated contradictory.
“The older the driver, his vision decreases, and the more he sleeps, he is much more efficient than a younger person. Some things fall, but some things improve.”
(Participant No.4, 40 years old)
Other participants severely emphasized the importance of driving experience and believed that younger and low-experienced drivers generally are associated with a higher risk of drowsy driving.
“The trained driver, knows what to do when he is fatigued.”
(Participant No.12, 68 years old)
Most drivers were married and believed that family responsibility leads to drive cautiously. However, to supply the family’s financial requirements, they preferred to reduce their rest to earn more.
Lifestyle
Drivers encounter various strains, including reduced physical activity due to full-time sedentary work, inactive lifestyles, and obesity. According to the participants, inactive lifestyles (4/14) and obesity (7/14) increase the possibility of drowsy driving.
They discussed how life habits have a considerable impact on their alertness. The majority of participants believed that drug addiction is a significant issue for bus drivers in the context of fatigue. While smoking and drug usage are general measures to maintain adequate alertness during driving, they emphasized that dependence and irregular consumption would lead to fatigue and drowsiness. They also stated that drug addiction negatively influences the drivers’ sleep quality and quantity and leads to excessive daytime sleepiness and fatigue while driving.
“Everyone with a history of accidents that comes to my mind was addicted, too.”
(Participant No.1, 56 years old)
“Addiction to cigarettes, drugs, and the habit of consuming these substances makes driving abnormal.”
(Participant No.2, 60 years old)
Vehicle factors
Design and performance
Thematic analysis of vehicle-related factors in drowsy driving resulted in design and performance categories generation. Participants considered car comfort as an essential factor in causing driver fatigue and drowsiness. (5/14).
“Vibration of the steering wheel is annoying and makes the driver experience an unsatisfactory situation. It hurts him mentally and physically. It injures his shoulders, and the driver gets exhausted. ”
“I have a 457 model 2008 gas bus. It seems that I tow and pull this bus myself. When driving the Scania bus, our traditional Oghab brand, it has an air conditioner and is very comfortable; you are satisfied and say that the world is mine.”
(Participant No.6, 51 years old)
Drivers stated that they must maintain the vehicle appropriately, check equipment safety performance before undertaking their shift, and transport the vehicle for repair if there is a breakdown. They declared that car maintenance is a hassle and demanding task and takes tremendous cost. Simultaneously, it takes a lot of energy and time, which adds to fatigue due to the limitation of their break time between shifts.
Job factors
Thematic analysis of job factors in drowsy driving conditions resulted in three categories: 1) Task requirements, 2) Sleep quantity and quality, and 3) Circadian rhythm.
Task requirements
According to reports, drivers work in different shift patterns regulated by the operating companies. Although these patterns were not offered in this study, participants believed that irregular shift patterns and long working hours could cause fatigue. As drivers mentioned, working in different shifts is a significant cause of fatigue due to its negative effect on the body’s system, especially when facing significant changes at the beginning and the end of the work shifts.
Sense of responsibility for the safety of passengers was another fatigue risk factor mentioned by drivers. They stated that providing safe services and reaching the destination on time makes bus drivers’ jobs somewhat different.
Some drivers highlighted the impossibility of choosing the time for a break when they feel fatigued and drowsy (7/14). The majority complained about GPS restrictions because they could not stop the vehicle without an acceptable reason. Being reproached and questioned immediately after stopping the vehicle for any reason, such as technical defect, or fatigue, was unpleasant. In other words, they do not have a possible choice to choose a break time.
“When GPS is turned on, we are under scrutiny. We cannot step aside and rest even if we need to rest“.
(Participant No.12, 68 years old)
Besides, drivers explicitly stated that there is less freedom to stop the car and rest if necessary due to passengers’ complaints. While truck drivers, or long-haul drivers, can stop the vehicle and take a break if needed, possibly even a short nap, bus drivers have strict time schedules to follow and cannot take a break whenever they would like.
Quantity and quality of sleep
All of the participants were concern about both sleep quality and quantity. In their opinion, sleep deprivation amongst bus drivers is common and may increase fatigue and accident over long journeys. Therefore, to have a safer journey, it is essential to get continuous sleep before the trip.
On the other hand, most participants stated that they do not have a reliable place to sleep during their work shifts (9/14). Also, due to lack of a suitable place to rest between work shifts, which directly affects sleep quality, they cannot sleep before the shift beginning adequately. From the drivers’ perspective, place features such as temperature, environment silence, vibration, and air conditioning are essential in their sleep quality. As loss of sleep quality can indirectly lead to drowsy driving problems, it is necessary to provide these expectations. Most of them considered it necessary to create places for sleeping in destinations to avoid sleeping or resting inside the cabin or vehicle after the work shift.
“Unfortunately, the drivers go in the cabin and sleep in the heat. They do not sleep well at all. They do not have an air conditioner. They are not able to keep the car on for 5 hours.
“If an appropriate sleeping place were made, the drivers would be comfortable and safe. There would not be any problem; otherwise, I do not think anyone can sleep comfortably in the cabin. ”
(Participant No.6, 51 years old)
Circadian rhythm
There was a range of times when drivers reported being most likely to feel fatigued, which were as follows: at the beginning and end of work shift, after lunch, or midnight. Most of drivers reported feeling drowsy in the early morning and mid-afternoon, and some mistakenly attributed it to drowsiness after eating (13/14).
Environmental factors
Qualitative content analysis of environmental-related factors in drowsy driving resulted in two categories: 1) Physical and 2) Economic factors.
Physical environment
An example of physical conditions reported by participants was the straight and monotonous road. High and low arousals are associated with performance decrements, and optimal performance occurs when an appropriate arousal level keeps the driver alert but not stressed. On the other hand, a fatigued or drowsy driver due to monotonous conditions (for example, prolonged driving on a straight road with low traffic) is at greater risk of losing control of the vehicle or failing to respond to hazards in times. The majority of participants agreed that desert, straight and monotonous roads are challenging for driving and make them prone to drowsiness. They gave many real examples of these situations.
“When driving from Tehran to Mashhad, the road up to Damghan, Semnan is smooth with no ups and downs in the center of the desert, all of which cause fatigue and drowsiness”.
(Participant No.3, 46 years old)
“When I drive on a beautiful road, I get excited and say, ‘Wow, beautiful nature. It relieves fatigue, and it is exciting for me.’
(Participant No.5, 57 years old)
Several drivers reported difficult simultaneous driving conditions, such as early shifts in combination with monotonous driving.
“For example, driving from 02:30 until the morning on a straight and quiet highway or road, with no turns, in a static position, without gear changing, no mobility, and without stress and fear of turns, will make the driver fatigued and drowsy.”
(Participant No.9, 57 years old)
Some roads are designed defectively or need repairs. Driving on such roads increases the risk of accidents, especially during night driving, and will lead to fatigue. After the human factor, the road condition was the second factor most drivers expressed as a fundamental cause of fatigue and road accidents.
The seasons were other factors that play a significant role in the incidence of drowsiness and traffic accident. The season, especially spring and somehow winter, were other factors reported by most drivers that cause drowsy driving.
Economic environment
Due to the economic conditions prevailing in developing countries such as Iran, the difficulty of providing livelihood, high vehicle maintenance costs, and high insurance premiums were the factors that can be incentives to more extended driving periods without any rest or sleeping and involved in a higher number of crashes amongst Iranian suburban bus drivers (10/14). Besides, Iranian bus drivers’ poor economic condition also motivates them to falsify their logbooks or work more hours to earn extra monetary benefits.
“When the cost of living goes up, you have to work harder. When you work harder, you do not have time to rest.”
(Participant No.7, 40 years old)
“I prefer not to hire an apprentice driver, I drive myself, and get more money myself, even though I know it can be a dangerous option. “
“When costs are so high, some co-workers drive more time using other drivers’ documents and falsify logbooks.”
(Participant No.9, 47 years old)
Countermeasures
All drivers were aware of the effectiveness of coping measures such as eating and drinking for fatigue and drowsiness and presented them as a response to drowsiness. However, according to the participants, most of these methods will be ineffective if they do not have sufficient sleep (9/14).
A list of countermeasures and the frequency of drivers’ reports are provided in Table 4. For most of them, many of these measures require little effort and do not significantly affect their driving. It is noteworthy that several drivers mentioned the effectiveness of napping, while others considered it destructive (3/14). None of them are allowed to use communication devices such as mobile phones because it might distract them.
Countermeasures to deal with fatigue and drowsiness and the number of reports
Countermeasures to deal with fatigue and drowsiness and the number of reports
This study reveals that drivers significantly understand personal, occupational, environmental, and vehicle-related factors as contextual factors affecting fatigue and road accidents. The four themes that were established from our findings provide an essential insight into these working conditions.
First, the findings of the current work are broadly in line with the study conducted by Biggs et al. [26]. The similarity of drivers’ views in 2009 suggests that there has been little advancement in practical mitigation of bus driver fatigue during this period. Fatigue in bus drivers persists as a problem that future works should address [27].
We found a more significant number of codes and categories, and thus more contextual factors, associated with job factors. When asked to define fatigue risk factors, many drivers noted that lack of sleep, poor sleep quality, and long working hours are vital issues. These issues appear to be persistent problems in the transportation industry [28, 29]. Indeed, researches have shown that one of the leading causes of fatigue-related incidents is attentional lapses due to insufficient sleep and inadequate rest [9, 30].
Although environmental factors strongly affect the quality and quantity of sleep, the lack of appropriate places to rest and their high prices made the drivers sleep in the cabin under heat, cold, ambient noise, and bothersome conditions. With high humidity, background light, and irregular noise, the probability of poor sleep-environment is 39.5%, 38.5%, and 44.5%, respectively. Also, with adverse sleep conditions, the likelihood of inadequate sleep quality is 59%, leading to fatigue/drowsiness [31, 32]. This report emphasizes that the companies must provide more welfare facilities such as resting places to improve and maintain drivers’ working conditions. Further, it requires more effort to encourage drivers to have a healthy lifestyle to decrease fatigue.
Increased driving time is known as a notable factor in distracting drivers’ consciousness. In addition, driver fatigue increases as a function of long driving hours [33–35]. Prolong driving time has been previously reported as a risk factor in the transportation industry, and it is not a unique problem for bus drivers. It was detected amongst taxi and trunk drivers in china by Meng et al. [33] and finnish heavy vehicles in Australia by Thompson et al. [36]. This report indicates that everyone will probably experience fatigue, whether due to the work conditions or lack of enough sleep in daily life. Hence, a management system must be chosen and is required to encourage the drivers to have a healthy lifestyle. Also, this approach demonstrates and reflects the importance of researches that have linked fatigue to safety issues.
Vehicle and physical environment are other sources that directly contribute to fatigue and road accidents [37]. In this research, participants’ comments focused on vehicles’ discomfort, steering wheel problems, and road deficiencies. They noted that fatigue is mainly caused by defective road conditions, especially potholes and road deficiencies. The relationship between nonstandard impaired roads and mental or physical fatigue and traffic accidents is well presented by Mekhlafi et al. [4]. In addition, participants reported that their vehicle needed continuous service and maintenance, which reduced their periods of sleep and rest during the day. It seems that the high rate of traffic accidents in Iran could be decreased by replacing outdated vehicles and improving roads.
In the present study, drivers reported that spring and winter caused fatigue/drowsy driving. The results align with some previous researches; Feng et al. analyzed the records retrieved from the Buses Involved in Fatal Accidents (BIFA) database from the USA. Based on the survey results, in comparison with spring, summer lightly decreases the plausibility of more severe accidents. In contrast, autumn and winter are associated with increased accident severity [38].
According to the Haddon matrix, risk factors in the pre-crash phase and at the environmental level include physical and socioeconomic factors and economic pressure (for example, social deprivation) [39, 40]. The socioeconomic status disparity may stimulate drivers’ motivation to drive long hours. This report shows that there are many opportunities for overtime among Iranian bus drivers. The drivers agreed that overtime contributes to fatigue levels since it increases the total hours of the working period. It is reflected in the qualitative study by Biggs et al., which identified extended shift cycles (12 working days and 2 days off) as a significant factor in fatigue. Also, it was generally agreed that drivers were working in these shift patterns because of financial problems [26].
As suggested in the literature, in the etiology, the leading cause of the drowsy driving shifts from human-related factors to socioeconomic environment-related factors. Moreover, the primary interventional focus on drivers’ behavior shifts to the concentration on the policy levers to attain a comprehensive approach [41, 42]. Local governments in Iran should regulate bus companies to ensure that the drivers’ working hours are reasonable and paid based on their work quality.
This qualitative investigation demonstrated the individual characteristics as shown in the literature [12, 43–45]. However, participants have presented different reports regarding the age effects. The literature indicates a U-shaped relationship between drowsy driving and driver age, so young drivers are at risk for accidents more than older drivers [26, 46]. This issue may be due to young drivers’ lower experience compared to middle-aged drivers in controlling drowsiness. Another possibility is that young drivers are more eager to earn more and travel longer.
The literature indicated more fatigue amongst who reported living alone [43]. According to the findings of this study, family responsibility is a more appropriate variable than marital status to influence driver alertness. As mentioned by the participants, family responsibility may lead to a need for long working hours and higher exposure to drowsy driving risks.
Although mobility and physical activity maintain the driver’s alertness, physical and mental health [4, 47], most drivers stated that they could not exercise regularly due to long work shifts. Recently, innovative solutions have been proposed to create an active sitting position, for example an active chair system [48], movement in the back and upward and downward [49] has shown positive effects on well-being, reducing driver’s passive task-related (TR) fatigue, and maintaining driver alertness [49–51].
Most participants stated that drug addiction is a common method amongst drivers to maintain alertness while driving; however, they believed it is wrong. A survey in Peru showed that 75% of professional drivers had a drug addiction [52]. Another survey in Iran showed that drug addiction is more prevalent among public suburban bus drivers than other substances [53]. The using these substances increases the drivers’ drowsiness and fatigue during working hours [54].
In the majority of studies, smoking as a countermeasure is adopted to increase alertness. However, Carone et al. indicated that smoking might have adversely affect sleep [55].
Workplace restrictive conditions such as tight work schedules and food or drink consumption limitations have the most substantial influence on selecting countermeasures [56]. According to a report of an expert panel convened by the U.S. National Center on Sleep Disorders Research and the U.S. National Highway Traffic Safety Administration, except for a short nap and caffeine, which can provide temporary relief, all other coping activities have no scientific basis to support their effectiveness in counteracting fatigue [57]. Therefore, the present paper emphasizes the requirement of education and concentration on sleep hygiene and napping and caffeine-controlled use to promote alertness and the development of a reliable in-vehicle and out-of-vehicle countermeasure. [48, 58].
Conclusion
The study results show that drivers have a comprehensive understanding of the contextual factors affecting drowsy-related crashes. This study’s results can provide a comprehensive guide in developing and managing effective educational and technical interventions with long-term benefits to prevent or reduce drowsy-related crashes. Furthermore, it highlights the importance of attention to contextual factors, especially human factors, to provide precise driver fatigue detection and predictive models and systems. According to identified factors, it is suggested to conduct further studies amongst professional drivers to quantify the contextual factors contributing to drowsy driving conditions.
Despite the significant findings, some limitations should be acknowledged to be considered in future research. This study was conducted amongst a sample of suburban bus drivers. Differences in the truck, bus, and demands of taxi drivers’ job may determine potential differences in their fatigue experiences, fatigue factors, attributes related to fatigue, and countermeasures. Information gathered from this research reveals the need for further investigations to evaluate contextual risk factors affecting drowsy driving and quantify effects of drivers’ fatigue in different driving groups.
Previous investigations of drowsiness as a causal factor in motor vehicle crashes have involved retrospective studies of data drawn from police crash reports, while the current study surveys the general driving population. Future studies are recommended to manipulate both approaches to provide more precise insight into specific factors that put drivers at risk for involvement in a drowsy-related crash.
Conflict of interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Footnotes
Acknowledgments
The authors thank the volunteering participants for their trust, engagement and valuable time they invested in this study.