Distracted driving is where the attention of the driver is divided among different activities, i.e., not 100% dedicated to the task of driving. A Federal government study in 2015 indicated that roughly 11% of the freeway deaths were caused by distracted driving (CNBC, 2015). Distracted driving can involve the application of in-car infotainment system such as adjusting a radio, temperature or taking eyes off the road for any reason. The US National Highway Traffic Safety Association (NHTSA) reported that 450000 people were injured and 5500 lost their lives in motor vehicle crashes attributable to distracted driving in 2009 (NHTSA, 2009).
Distracted driving has been categorized into 3 different types: visual, manual and cognitive. Visual distraction is that situation where the driver’s eyes are not focused on the road. Manual distraction is that situation where the driver’s hands (and feet) are not in position to control the vehicle. Cognitive distraction is that situation where the driver’s thoughts are not 100% devoted to the task of driving.
Distracted driving not only involves the use of mobile phones as a secondary task, but also interacting with in-vehicle information systems as secondary tasks. There is evidence from research that proved involving into secondary tasks have detrimental effects in the driving performance in several ways (e.g., corrective steering, lane deviation, reaction time). Distracted driving is a major threat to public safety and is the leading cause of the United States motor vehicle crashes. Distracted driving is not only the driver engaging in secondary activities but also driving under the influence of drugs or alcohol. The drugs like antihistamines causes dizziness, and marijuana, causes slow reaction times prescribed for various medical conditions. These chemical compounds are known to impair driving performance and cognitive functions.
The research is focusing on all the kinds of distraction: manual, cognitive and visual. The cognitive as well as visual undermine the driving performance, but their effects are seen quite different to each other. Cognitive tasks are known to mitigate the variance in lane position, while visual tends to increase variance. Since cognitive distraction is difficult to measure, however there have been studies that have fairly explained the distraction caused by deviation from concentrating in driving.
The measure of visual distraction focuses on glance behavior or on vehicle control and is the best way of quantifying the visual parameter. This measure is in the form of duration of longest eye glance and the number of glances. The studies suggest that eye glances away from the road produce corrective steering which also quantification of manual distraction. The eye movements are coordinated with steering movements to keep a vehicle within lane margins. Failure to coordinate between the two movements might lead to declined vehicle control and to dangerous changes in vehicle state, such as weaving. It is possible to differentiate between the different categories of distraction. The most problematic type of distraction is the combination of the various levels of visual and cognitive distraction, e.g., phone dialing and text messaging (National Safety Council, 2012).
Texting and Driving
In recent years, mobile phone use while driving has emerged as a growing concern. The use of mobile phones has increased exponentially and also there has been a steady increase in the number of people engaging in mobile phone use while driving. The use of mobile phones while driving has led to the increase of motor vehicle crashes. Texting while driving is considered as the most commonly witnessed distractions while driving. Motor vehicles driving process needs undivided attention and the application of visual, auditory and tactile senses for the safety. Simulation and experimental vehicle studies have indicated that drivers who engage in using cell phones have significantly increased the rate of motor vehicle crashes. Regardless of the risk associated with cell phone use while driving, 31% of adults ranging from 18 to 64 years old have reported upon reading, sending text messages or emails (Morbidity and Mortality Weekly Report MMWR, CDC, March, 2015)
The findings by Cook & Jones in 2011 have reported rising rates of texting and driving.
The National Highway and Traffic Safety Administration (NHTSA) reported 11% of drivers use cell phones at any particular time while driving. The Fatality Analysis Reporting System (FARS) confirmed that the proportion of driving fatalities attributed to driving distraction have increased from 10.5% in 2005 to 15.8% in 2008, and it is partly due to texting while driving. The theory of dual-task performance states that if two different tasks utilize similar resources, performance of both the tasks will be impaired when they are performed concurrently. Driving and texting require some of the same visual and cognitive resources. Therefore, driving performance can be impaired with texting and driving.
The evaluation of the driver’s performance by Jiboe He (2014) while they sent and receive text messages via mobile phones, they employed the use of an in-vehicle texting system through Bluetooth wireless connection. The in-vehicle system allows control through the steering wheel to send pre-set texts and receive the messages. Results showed that hand-held texting requires greater mental demand, longer and more frequent glances away from the roadway compared to the vehicle infotainment system. Also, the Hosking, Young and Regan used a driving simulator to study the effect of texting and driving behavior during different driving situations. The driving situations included vehicle following: pedestrian avoidance and lane-changing tasks. The participants were trained to use a cell phone with a text input and were asked to answer simple questions, such as what is your favorite food, and the questions were pre-loaded on the phone. Participants were instructed to read the text in 15 seconds and were then prompted for a response. The study revealed that while texting, subjects spent more time not looking at the roadway, missed the lane changing instructions and deviated from the lane more frequently.
The study conducted by Drews et al. (2009) also involved participants using a driving simulator. In this study, they were supposed to follow a lead vehicle while having a free form text message conversation with a friend using their personal phone. This revealed that texting was responsible for slower brake onset times, poorer lane keeping and more crashes during dual tasking. There was another study done by Klauer in 2006 resulted that dialing a hand-held device increased a crash or near-crash roughly by 2.8 times compared to baseline.
Road traffic safety has emerged as a major public health concern. The previous research on the motor vehicle crashes between 2 or more vehicles are often the result of one of more of the drivers distracted from the primary task of driving. There is an inverse relationship between cell phone use and driving performance, and this has been well documented. New York was the first state to ban talking on a handheld device while driving (New York Times, 2007). There were more states that followed the legislation and this law resulted in lowering single vehicle, single-occupant accidents between 2007 and 2010 (Alva O. Ferdinand, 2015). Some states implemented the law that explicitly banned drivers from texting, which includes reading, sending texts or emails via a portable electronic device.
The statistics state that 26% of all the car crashes in 2014 involved cell phone use (Distracted driving, NHTSA, 2014). Approximately 9 people are killed every day because of a distracted driver and more than 1000 people are injured every day due to driving distraction. Ten percent of drivers from ages 15 to 19 years old who were involved in fatal car crashes were reported as distracted drivers (Distracted driving, NHTSA, 2014). The problem is serious and is known to exceed the dangers of driving under the influence of alcohol in terms of injuries and deaths (Caird, AAP, 2014).
Driving Under the Influence
Driving under the influence (DUI), also known as driving while intoxicated, drunk driving, or impaired driving is the crime of driving a motor vehicle while impaired by the effects of alcohol or drugs, including medicines prescribed by the physicians. Driving under the influence is a serious threat to public safety and health. 242,900 people died worldwide in 2002 alone due to alcohol-related traffic accidents (Miller, 2014). The NHTSA report says that 32% of all the fatal car crashes involve an intoxicated driver or pedestrian. Driving is a task that requires attentiveness and the ability to make quick decisions on the road, to react to changes in the environment and execute specific, often difficult maneuvers. Despite increased public awareness, drivers still continue to drive drunk and drugged.
Alcohol and Driving
Alcohol is mood altering compound. It is a depressant, as it slows down the functions of central nervous system. The risk that a driver is while driving under the influence of alcohol will die in a crash is at least seven times higher that of drivers without alcohol in their system. The NHTSA report from 2006 said that of all the teen drivers killed, 31% of them had been drinking. Driving under the influence is never justified because it endangers the lives on road. Alcohol slows down the reaction time and this results in fatal crashes.
Drugs and Driving
There are certain compounds, prescribed and controlled for their use for various medical conditions, result into euphoric effects. The popular brands like Clariton and Benadryl are antihistamines that are used in allergy medicines, cough medicine and cold tablets and cause dizziness and drowsiness. For example, marijuana is proven to lower reaction time, impair judgement of time, and decrease coordination (Sewell, 2009). The drivers under the influence of compounds like cocaine and methamphetamine be involved in reckless and aggressive driving. Driving under the influence of such substances affects our ability to drive safely by changing our physical, emotional and mental condition. In 2009, NHTSA did a study and revealed that more than eighteen percent of fatally injured drivers tested positive for at least one illegal or prescription drug. Another NHTSA survey in 2009 found that one in five motorists killed in car crashes tested positive for drugs other than alcohol.
Marijuana – History in Brief
The introduction of Marijuana in the United States in the early 1600s was done by Jamestown settlers who used the plant in hemp production; hemp cultivation has been a prominent industry until the mid-1800s (Deitch, 2003). The census of 1850 in the United States recorded over 8,000 cannabis plantations of at least 2,000 acres (U.K. Cannabis Campaign 2011). During the 1800s, cannabis was commonly used by physicians and pharmacists to treat a broad spectrum of ailments (Pacula et al. 2002). The surprising fact is that marijuana was included in the official list of recognized medicinal drugs in the United States Pharmacopoeia from 1850 to 1942 (Blitz 1992).
The access to marijuana for medical and recreational purposes has become a controversial issue throughout North America. Although at the federal level the production, possession, sale, and distribution of cannabis is not legal and some is subject to strict controls and sanctions, it is widespread among the states. There is a great variation in the legal status of Marijuana in the United States. Marijuana is legal in over half of the states and recreational (for personal to get high) is legal in many States. People believe and see cannabis as a safe substance and a natural medicine used to treat disease and/or relieve the symptoms of a wide variety of medical conditions. The District of Columbia and 23 other states have approved the possession and use of cannabis for medical purposes as of November,2015 and there are 9 states who have legalized use of marijuana medically and recreationally until today. The widespread use of marijuana has created an urgency about the status and safety of cannabis including driving under its influence.
Cannabis is a very popular recreational drug, secondary only to alcohol in its reported frequency of use in the world. The question arises what Marijuana is. Marijuana is the dried flowers and leaves of the plant Cannabis sativa where Cannabis is the genus and sativa are the species. This the most common species used recreationally and medically, but there are other related species too. It is typically smoked or vaporized for its euphoric or psychoactive effects. There are other ways of consuming marijuana like in the form of oil or resin which are the extracts or the plant material that are concentrated. These are ingested orally either directly or after being prepared into various edible products, including brownies, or candy.
The major component of cannabis is THC (Tetrahydrocannabinol) which is responsible for the psychoactive effect. Once it is ingested irrespective of the route whether orally or smoked, it gets distributed throughout the blood stream and crosses the blood brain barrier. THC is a highly lipophilic compound and being lipophilic in nature, it concentrates readily in fatty tissues including the brain. The body breaks THC into two principal metabolites namely, 11-hydroxy-THC and 11-carboxy-THC. The hydroxy compound is known to have psychoactive effects similar or greater than THC and it also has increased permeability for the blood-brain barrier. Carboxy-THC is an active metabolite.
First pass metabolism of orally administered cannabis greatly reduces the bioavailability of THC by this route, however does produce increased 11-OH-THC concentrations that contribute to observed pharmacodynamics effects (Huestis, 2009). The THC concentrations after smoking drops quickly, but the metabolite which is water soluble, are detected for longer periods of time in the circulatory system. To understand the cannabinoid blood concentration and THC disposition biological matrices, quantification of THC, 11-OH-THC and THCCOOH is required. Marijuana produces dose related cognitive and psychomotor performance and this is an important factor to consider because this dose producing effect is related to driving a motor vehicle and driving may be impaired when under the influence of cannabis.
Driving while impaired by marijuana is dangerous because just like alcohol, marijuana negatively affects the skills required for safe driving. Marijuana has been proven to slow the reaction time and ability to make decisions. Marijuana impairs coordination, distort perception, and lead to memory loss and make the problem-solving ability complex. The risk of impaired driving because of marijuana and alcohol combined seems to be far greater than that for either by itself.
Effect of Marijuana on Driving
The 2007 National Roadside Survey reported that 4.5 and 8.6 percent of daytime and nighttime drivers, respectively tested positive for cannabis (StopDUID.org, 2014). The survey done in 2013-2014 showed an increase in nighttime drivers testing positive (12.6%) (Waller and Beirness, 2014).
There are some jurisdictions followed these days, namely, Drug Recognition Experts (DREs). DREs are specially trained police officers who follow specific guidelines to determine drug impairment in motorists. These experts closely evaluate a person’s eye movements, behavior and other activities that point out to the drug influence. Forty-four states including Michigan and the District of Columbia have Drug Evaluation and Classification Programs in running to train DREs.
Effects of Marijuana on Driving – Cut-Off Concentrations
Cutoff levels are the detection thresholds for compounds that are set on the testing instrumentation. There is an effect-based threshold value set for alcohol in the blood while driving is set typically at .08 percent or higher, which is illegal in all 50 states except Utah (0.05%). Alcohol is eliminated from the body rapidly from the lungs, therefore it is relatively easy to measure a motorist’s BAC at the time of driving. The device that is used to measure the blood-alcohol concentration (BAC) is called Breathalyzer test, this is not considered to be quite accurate. The reading with 0.08 percent or higher is not the only factor considered to pleading guilty or conviction on DUI charges.
There is not a nationally accepted threshold value for Marijuana that corresponds to the impaired driving performance as there is for alcohol. There are different threshold values followed by different states (the states where Marijuana – recreational and/or medical – is legal), but these values are not effect-based. For instance, Colorado law specifies that drivers with five nanograms of active tetrahydrocannabinol (THC) in their whole blood can be prosecuted for driving under the influence (DUI) https://www.codot.gov/). On the other hand, in the state of Nevada the cut-off is 2 ng/ml in the blood.
In the only prospective study to date on the issue of marijuana blood concentrations and driving performance, Hartman et al (2015) reported that the concentration of marijuana required to produce a degree of driving impairment (increase in SDLP) similar to that produced by 0.08% ethanol was 13.2 ng/ml. This number is considerably higher than the blood concentration used as the cut-off for ‘stoned driving’ in any state.
This present was conducted to evaluate the measure of potential for impairment while driving under the influence of Marijuana. To accomplish this we studied a group of Medical Marijuana subjects and a group of controls. We evaluated their driving performance by measuring lane position deviation and steering corrections during non-texting driving and during periods of texting while driving. We also measured glance behavior during bouts of texting while driving.
