An important study about what kind of truck and bus driver behavior leads to distracted driving and drowsiness conducted by researchers at the Virginia Tech Transportation Institute offers some good news for a change, while at the same time suggesting further avenues for productive research.
The good news is that public safety message warnings over the years about the danger of using a handheld cell phone to text, talk and drive seems to have penetrated at least that portion of the population who are professional drivers. In more surprising good news: The study concludes that dancing and talking or singing seem to be good ways to stave off drowsiness.
More than 3.8 million miles of naturalistic data were collected from seven fleets and 10 locations under an onboard monitoring study. A total of 43 buses, 73 bus drivers, 182 trucks and 172 truck drivers participated in this study. The publication of the research was sponsored by the Federal Motor Carrier Safety Administration (FMCSA), which was the intended audience, along with fleet operators and other stakeholders.
“Key findings from the study showed an overall decrease in cell phone use compared to previous research,” the report said. “Hands-free cell phone use was found to be protective as it likely helps drivers alleviate boredom, while hand-held cell phone use was found to be risky as it takes the driver’s attention away from driving tasks. Additionally, the eighth driving hour showed the highest rate of safety critical event occurrence.”
The system used in the study to gather data included five video cameras installed in different places surrounding the driver. In addition, various channels of kinematic data were continuously collected to monitor driver behavior.
The data was processed with a set of sensor trigger values to identify safety critical events (SCEs). The video and data results were then grouped into one of five SCE categories: crash, near crash, crash-relevant conflict, unintentional lane deviation, and no event. There were 4,102 events and 14,198 periods of normal driving.
One noticeable limitation when considering driver drowsiness research is that none of the fleets were dedicated over-the-road operations; therefore, not many drivers drove extended hours, the researchers noted. Because the data was collected from mostly local and regional fleets, this points to the need for additional studies if the data can be used to analyze the effectiveness of hours of service regulations on commercial drivers’ license holders in long-haul operations.
One of the key findings and takeaways from this study is the reduction of cell phone use among both truck and bus drivers, the researchers pointed out. One major difference from the past that was found was safer use of hands-free talking when compared with handheld devices. Talking/listening on a hands-free device showed a reduced risk, while browsing and texting was evidence of an increased risk of the driver being involved in an SCE.
Other actions taken by both the bus and truck drivers that showed an increased risk of being followed by an SCE include reaching for an object; interacting with an electronic dispatching device or other electronic device; adjusting/monitoring other devices integral to the vehicle; external distraction; reaching for food- or drink-related items; and removing or adjusting clothing.
Let’s Go Dancing
What were the driver activities that helped to prevent SCEs? “The results show that dancing is protective for both bus and truck drivers,” the researchers reported. “Talking/singing was also found to be protective for truck drivers. This could have been talking/singing to the radio themselves, or surrounding traffic. Neither talking nor singing requires a high visual load, so these results are not surprising.”
Other activities show a significant increased risk of being involved in an SCE when compared to baseline driving for truck drivers. These include reading; reaching for an object; interacting with an electronic dispatching device or other electronic device (e.g., GPS, satellite radio); adjusting and monitoring another device integral to the vehicle (e.g., adjusting seatbelt, adjusting seat height, or adjusting mirrors); external distraction; reaching for food- or drink-related item; and removing/adjusting clothing.
Where drivers choose to look can have a negative effect as well. Results for both bus and truck drivers showed that the longer the driver’s eyes were off the forward roadway, the greater the risk of being involved in an SCE, with a significant increase once the driver’s eyes were off the road for more than two seconds.
Truck SCEs stemming from engaging in a secondary task of browsing a cell phone or computer screen had one of the highest mean eyes-off-roadway time, totaling as much as four seconds, although driving while texting had the highest mean eyes off roadway time of five seconds.
The researchers also examined the effect on safety of different external environmental factors, such as weather, sunlight and road conditions. The majority of the SCEs occurred in daylight, with no adverse conditions, on non-junction roadways, and on divided roadways for both kinds of drivers. SCEs were more likely to occur for bus drivers in moderate traffic areas such as airports and business/industrial areas, and for truck drivers in relatively low traffic areas, such as interstate highways.
Overall, it can be inferred that there is a significant increase in risk associated with increasing hours of driving, the researchers found. As time goes by behind the wheel, the SCE risk rate can increase to two to three times higher than in the first hour, hitting peak value at the eighth hour.
When the researchers applied a pairwise comparison, the results show that the first 10 driving hours can be further grouped into three parts: low SCE rate (the first hour), moderate SCE rate (the second hour), and high SCE rate (the third hour through the 10th hour).
The SCE results show multiple peaks, including the second, third and ninth hour. There was no pattern of increasing drowsiness after the eighth or ninth hour. The timing and duration of the driver’s breaks could impact driving behavior, and the time-of-day of the trip could also affect drivers’ drowsiness, the researchers concluded. However, they noted that the results show no pattern of increasing drowsiness with driving hours.
“A deeper investigation of the drowsiness data revealed that although most truck drivers with long shifts begin their shift in the very early morning hours, fatigue is highest in systematic baselines and SCEs from 1 am to 6 am,” the researchers stated. “While there was not a statistically significant difference in the third driving hour for systematic baselines and ninth driving hour for SCEs, it appears that time of day and the driver’s natural circadian rhythm may play a role in their drowsiness.”
The researchers concluded that their study invites further investigation of the issues it raised, especially in regard to driver fatigue among long-haul truck drivers, who were unrepresented in the study sample.
