Driving is an activity of daily living for many people. Many people in different parts of the world are seeking training in driving. However, while driving becomes common, the risk involved in the process is significant. According to Mueller (2015), motor vehicle accidents are the leading cause of mortality among youth aged 11 to 27. In 2011 alone, more than five million vehicle crashes were reported. These accidents resulted in 32367 deaths. Common and preventable driving errors may explain the happening of accidents (Wynne et al., 2019, p. 138). As a complex task, driving involves perception, cognition, sensory, and motor functions. There has always been a need to understand the body processes involved in the driving process, the issues that cause errors and accidents, and how accidents can be prevented. Such has caused an increased interest in technological developments, including driving simulators to study driving behavior. Besides, on-the-road tests have also become common. While both on-the-road tests and simulations have been used to understand driving behaviors like distractive, sleepy, and aggressive driving, there is a constant need to determine which of the two should be relied on for final decision-making.
Simulation Studies
Researchers have used simulation studies to understand behaviors in confined and controlled environments. According to Wynne et al. (2019, p. 138), simulations are essential when the study area is impractical, unsafe, or unethical to perform in real-life situations. Having emerged in the 1930s, they have attracted everyday use, especially in studies involving human behavior (Wynne et al., 2019, p. 139). Through their application in understanding driver behaviors, simulations have yielded significant revelations and contributed to the growing body of knowledge.
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A significant issue with simulations and controlled laboratory environments is their inability to produce the desired validity, consistency, and reliability. This concern primarily stems from the fact that simulations may not reproduce the actual real-world performance of subjects (Hussain et al., 2019). Thus, often, simulators fail to generate consistent results over time. Also, their validity comes into question frequently because of their constant failure to reproduce a real-world driving experience (Wynne et al., 2019, p. 138). Reed and Green (1999) explained that whereas the measurements of speed and driver positioning may be similar between simulation and on-road studies, it is still difficult to rule out that simulations cannot replicate some aspects of driving that may only be possible in real-world studies. For example, driver sleepiness, distraction, and aggression may only be measured perfectly by observing and analyzing real-world situations. Meuleners and Fraser (2015, p. 17) also agreed that on-road studies and simulations are similar in most aspects of driving, but on-road studies are still needed to confirm findings gained from simulations. Simulations may depict these aspects, but their representation is controlled and unnatural.
Driver distraction, if studied on the road, could potentially cause tragic accidents. However, simulators have enabled researchers to generate a considerable volume of information on the subject of driver distraction. Papantoniou et al. (2015) reviewed 45 scientific papers that involved driving simulators to study the various sources of distraction among drivers. The analysis concluded that the available volume of research on driver distraction contributed significantly to creating an understanding of the sources of distraction and how these affect driver behavior and safety. However, these simulation studies involved small samples of about 20-40 participants, which made it difficult to generalize findings. Also, Dunn et al. (2021, p. 108) studied how simulators have informed the development of automated driving systems. They stated that computerized systems, based on data collected from simulators, could control a vehicle for extended periods and allow a driver to disengage from the task for some time. Such served to reduce distraction and improve safety. Stavrinos et al. (2013) supported this by positing that texting and other distractions limited safety, but data from simulators could improve safety by informing the avoidance of distractions.
Driver sleepiness has also been extensively studied in simulations. Ahlström et al. (2017) posited that driver sleepiness studies using simulations are commonly done using alert drivers during the day and sleep-deprived drivers at night. Thus, many factors confound the results, including circadian rhythms, homeostatic influences, and lighting conditions. While studying the effect of light on sleepiness, Ahlström et al. (2017) concluded that lighting affected sleepiness among drivers. The authors recommended that it is necessary to ensure nighttime drivers receive sufficient sleep. Additionally, Fors et al. (2016, p. 22) compared driver sleepiness in simulations and on-the-road. Although they found similarities between simulations and on-the-road tests, they stated that safety concerns involved in on-road experiments are difficult to manage. Thus, simulators are the safest way to study driver sleepiness.
Aggressive driving has not been studied significantly in simulations. According to Sarwar et al. (2017, p. 52), perceived and observed aggressive driving behaviors may be modeled simultaneously. However, different factors come into play to influence the perception of aggressive driving behaviors. Thus, some drivers may perceive their behaviors as non-aggressive when others perceive them as aggressive. This creates a problem of relativity in the definition of aggression, and such may only be solvable through on-road experiments where an external observer makes the conclusions. Therefore, simulation studies may not significantly contribute to understanding aggressive driving behavior.
On-Road Studies
In contrast to simulation studies, on-road studies involve studying driving behavior on real roads. These studies include exposing drivers to different situations in a real car on a real street in the natural environment where nothing is controlled. While a researcher may control some aspects of the study, including road conditions, weather, and other influences like drugs and alcohol, a driver must inevitably drive in the natural environment where traffic and pedestrians are uncontrolled. Such studies present valuable findings on how and why drivers behave the way they do in different situations. Nonetheless, they are significantly dangerous to pedestrians and other road users, and a researcher must employ significant safeguards to ensure the trials are safe to the driver and other road users.
Studying driver sleepiness is best replicated in on-road studies. Anund et al. (2018, p. 71) studied sleepiness among city bus drivers in an on-road study in which they studied irregular working hours, split shifts, and stress levels. By involving 18 professional bus drivers, they noted that 5 out of all the drivers reached a high level of sleepiness that was deemed dangerous to the driver, the public, and passengers. Even though the study considered a limited sample size, their findings helped set the stage for further studies on driver sleepiness. Anund et al. (2018, p. 71) also added that whereas there were significant differences between the study participants, it was clear that shift working increased the possibility of sleepiness, and countermeasures are necessary to improve safety among drivers with split shift schedules. Persson et al. (2019) agreed with these conclusions by adding that on-road studies were vital in understanding sleepiness among drivers. Thus, real-world studies are a critical basis for future discussions on the subject of driver sleepiness.
Driver distraction has also attracted significant interest among on-road researchers. Yang et al. (2020) studied the effect of distractions in on-road level-2 automated driving, intending to establish glance behaviors among drivers at different levels of distraction. While exposing drivers to varying levels of distraction and varying hazards on the road, the researchers confirmed that high-level distractions significantly skewed off-road glance duration. This agreed with Wijayaratna et al. (2019, p. 108), who established that mobile phone distractions caused high-level distractions that greatly affected driving safety and response to hazards. While the two studies used limited samples, they are helpful because they made conclusions in naturalistic environments. Their findings, therefore, are more reliable than those from simulation studies.
Driver aggressiveness may be challenging to study in an on-road test because of the risk involved. However, Ma et al. (2019) discussed unusual driving behaviors using detection algorithms to analyze motion data. They concluded that aggressive driving is one of the inappropriate driving behaviors that contribute to traffic accidents. Thus, through on-road studies of motion data, it is possible to derive findings that will prevent road accidents. The study, however, was limited because of its focus on motion data instead of the actual drivers. Islam and Mannering (2020) agreed with this by explaining that aggressive driving was associated with numerous accidents and driving errors.
Conclusion
Overall, simulations and on-road studies are practical avenues of studying driving behaviors, each having its advantages and disadvantages. Whereas simulations are beneficial because of their ability to replicate real-world situations and enable researchers to study complex and potentially unethical aspects of driving behavior, they are limited in their inability to give fully reliable and valid findings. Thus, they are best when applied as preliminary studies of new technologies before being tested on the road. On the other hand, road studies are significantly risky to the driver and the public despite their high validity and reliability. These studies involve placing potentially hazardous experiments on roads that other people also use. Thus, despite their ability to generate highly valid and reliable findings on driver sleepiness, distractions, and aggressive driving, on-road studies should be approached with care lest they expose pedestrians, study participants, and other road users to potentially fatal accidents. Nonetheless, on-road studies should be relied on for all decisions made regarding traffic policies and road-use regulations. This reliance on real-world experiments should be adopted with significant limitations to ensure the safety of the public. Future driving studies should consider doing initial studies in simulators before shifting to on-road studies—the simulators aid in understanding fundamental aspects of safety and give preliminary findings.
References
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