Most researchers agree that attempting to pinpoint a single cause for a motor vehicle crash is not usually realistic. Nevertheless, researchers and road traffic authorities tend to concentrate on a single factor that can be seen as the main contributor to the crash for legal, research and other purposes [1, 22]. DeNicola et al. [23] studied the causes of MVCs in KSA over eight years (between 2004 and 2011). The authors found that the main causes of MVCs in KSA are as follows:

(1) Speeding: 35.69%

(2) Improper turning: 8.43%

(3) Improper passing: 8.01%

(4) Traffic signal violations: 7.88%

(5) Improper stopping: 7.81%

(6) Others (including using electronic devices, tailgating, stunting, changing lanes unnecessarily, etc.): 32.17%

Numerous other studies have also demonstrated that 80 to 90% of MVCs could be attributed to the behavior of road users [6, 24-33]. Almost all of these studies have agreed that behaviors, like exceeding speed limits, careless driving, unwillingness to wear seat belts, crossing red lights, and ignoring traffic rules and regulations, lead to high rates of traffic crashes and enormous human and financial losses in KSA. Although the crash rate due to the leading cause of MVCs, which is excessive speeding, has dropped in recent years, this rate is still alarmingly high when compared to other countries, like the USA, as the rate in KSA is 2.38 times that of USA [7, 34].

Researchers also have investigated the effects of gender and age on risky driving behaviors. Keeping in mind that women were prohibited from driving until 2018, research findings indicate that male younger drivers and expatriate drivers are consistently overrepresented in causing traffic collisions. Male younger drivers are significantly more likely to commit driving offenses than other groups of drivers. Besides this, the ever-increasing dependency on motor vehicles for transportation, lack of reliable public transport system, and the very large area of the country have created great opportunities for expatriate drivers to work in KSA [25, 35]. Those drivers were found to be responsible for about 40% of the MVCs in KSA [36], although they constitute one-third of the population [37]. This was mainly attributed to their coming from countries with high collision rates and aggressive driving behaviors [38] or from countries where right-hand driving is practiced, a situation which might be confusing for them since KSA has a left-hand driving system in place [39].

Another issue to be considered as a demographic factor is a driver’s age. The median age of the Saudi population is 26.7 years. This indicates that the drivers’ population is skewed toward a younger age range that is more likely to be involved in risky driving behaviors [23]. It is reported that teenagers are more susceptible to ignoring traffic signals in KSA, where more than 2,000 teenage drivers were caught running red lights in one year, possibly due to their unwillingness to yield to other drivers irrespective of the circumstances [33, 40].

The behavior of drivers is one of the crucial parameters to be considered in analyzing and understanding the causes of MVCs [33, 41-43]. To understand the behavior of drivers, Al-Khaldi [44] assessed the knowledge, attitude and practices related to driving of male students from the College of Health Sciences in Abha, Saudi Arabia.

Results revealed that more than 50% of the students were involved in crashes, with 22% of them getting injured and 13% being admitted to hospital. Results also disclosed that more than three-quarters of them had moderate to high knowledge of traffic regulations, and more than 90% believed in the importance of wearing seat belts. Most of the responding students also indicated that they had problems with the use of seat belts, including forgetfulness and anxiety.

In another study by Aba Hussein and El Zobeir [45], a sample of drivers from Qateef, Dammam, Al-Khobar and Jubail cities on the Eastern coast of Saudi Arabia were randomly selected to assess their knowledge and behavior in terms of traffic regulations and performance on the road. Results showed that 52% of the participants were previously involved in MVCs, 75% reported wearing seat belts, and 60% used mobile phones while driving. The authors concluded that knowledge of traffic regulations and driving risks of drivers did not match their behaviors.

Finally, it is worth mentioning here since alcohol consumption is forbidden in KSA, drink driving is not a common cause of road traffic collisions in this country, unlike in other countries.

According to the World Statistics Pocketbook issued by the United Nations [46], Saudi Arabia has 176.6 mobile-cellular subscriptions per 100 inhabitants. This is considered one of the highest rates in the world. This means that almost all drivers can access a mobile phone while driving a motor vehicle. There are strong indications that mobile phone use while driving is a contributing factor to road crashes in Saudi Arabia [33, 36].

Gharaibeh and Abdo [47] examined the knowledge of traffic safety issues and compliance among high school and university students. The authors found that 85% of participating students used their mobile phones while driving. Another study by Uchechukwu et al. [48] found that making or receiving phone calls while driving led to a seven times greater risk of being injured in traffic crashes among drivers in KSA than those who did not.

One of the major contributors to increasing the severity of any MVC is the non-use of protective devices, like seat belts [49]. It is well documented in the literature that failure to wear seat belts is a major risk factor for all passengers in moving motor vehicles because they are effective in reducing the risk of injury in crashes [3, 31, 43, 50, 51]. Head, neck, cervical and spine regions are most frequently and seriously injured body areas from frontal collisions to occupants unrestrained by seat belts [2.52].

Wearing seat belts was made compulsory for drivers and front-seat passengers in Saudi Arabia on December 5^th, 2000 [2]. Before that date, the wearing rate of seat belts was about 2% [53-55]. Moreover, children of less than six years of age were found to be exposed to higher risk during vehicle collisions than other age groups in Saudi Arabia, where this group constituted 7.2% of fatalities and 13% of injuries [56].

Official statistics also showed that there had been 4,848 fatalities per year before introducing the seat belt law in 2000, and these had been reduced by about 500 per year (i.e., around 20%) in each of the following two years. The number of injuries also was reduced by about 10% in the first year after enactment [57]. After enacting the seat belt law, the initial public awareness campaigns were accompanied by strict enforcement by traffic police. Bendak [2] recorded a significant increase in seat belt wearing rates from around 2% to more than 60% for drivers and from close to 0% to about 23% for front-seat passengers in the first few months after enacting the seat belt enforcement law in KSA. This led to a significant decrease in the number of head, spinal, pelvis and bleeding injuries due to MVCs. Nevertheless, in a follow-up study by Bendak [58], it was found that wearing rates dropped to 28% for drivers and 15% for front-seat passengers in the following years, mainly caused by less stringent law enforcement. Results of the same study also indicated that self-reported seat belt wearing rates by drivers did not match observed wearing rates. This was reflected through the much lower actual wearing rates than self-reported ones. This mismatch between beliefs and deeds was also reported by Al-Turky et al. [54], who found that 88% of drivers believed in the importance of wearing seat belts although only less than 3% of them wore them.

Al-Shammari [20] assessed the types of vehicle collisions that lead to deaths or injuries in Saudi Arabia. The author found that frontal (56%) and side collisions (27%) were the most frequently recorded types of all traffic crashes, leading to deaths or injuries. Other types of collisions (like rear-end collisions and rollovers) were responsible for causing the remaining 17% of deaths or injuries due to MVCs. The author also assessed injured body regions in MVC victims in KSA, and found that the head, thorax, arms and spine are the most injured parts due to MVCs. Finally, the author reported that 52% of the victims died at the crash scene, 5% died while being transported to the hospital, and 43% died after being admitted to the hospital.

More than one-quarter of severe road crashes in KSA involve pedestrians. This incurs a huge human and financial cost to the KSA society [59]. A detailed study by Al-Ghamdi [60] involving the evaluation of 638 pedestrian-vehicle crash cases in Riyadh found that nearly 80% of all severely injured pedestrians experienced multiple injuries and that 50% of them had head, spine and trunk injuries. The same study also revealed that 42% of all pedestrian victims were aged 15 years or younger, which made this group of pedestrians the most vulnerable to pedestrian crashes.

A worldwide important traffic issue is the growing number of collisions between animals and motor vehicles. One of the most common large animals involved in such collisions is camels in KSA [61-65]. A wide range of solutions were implemented in different countries to try to resolve this issue, but neither unique solutions nor consistent results have been found [61, 62, 64, 65].

Colliding with large animals produces a distinct pattern of injuries than other MVCs. In large animal collisions, there is usually a higher frequency of injuries to the victim’s head, neck, and upper torso area [65, 66]. More than 700,000 camels graze freely in KSA [67]. Recent official crash statistics show that more than six hundred camel-vehicle collisions (CVCs) occur annually in KSA [7]. MoT has applied several infrastructural measures over the past 30 years to prevent animal-vehicle collisions, including the construction of highway fencings and overpasses for camels. Consequently, the number of such collisions has dropped significantly, but this type of collision is still occurring. Because each camel weighs up to 726 kg, any camel-motor vehicle collision is expected to yield catastrophic consequences to the vehicles involved and their passengers. Therefore, more aggressive mitigation measures should be implemented to prevent CVCs [45, 65, 68].

A historical trend for the crash severity level was also assessed by computing an annual odds ratio (OD) of crashes between 1970 and 2019. Fig. (3) demonstrates this trend with upper and lower limits and a 95% confidence interval while taking the 1970 MVC figure as a base point. The trend shown in Fig. (3) identifies that no improvement in the odds ratio of crash severity has been recorded in KSA between 1970 and 2019, except for a short period between 1985 and 1990. It should also be noted that the OD of crashes has increased significantly since 2010.

Fig. (3). Odds ratio of crash severity (1970-2019).

For a better understanding of the extent of human losses in KSA, Barrimah et al. [69] incorporated health registration data on deaths due to traffic crashes. They showed that death rates due to traffic crashes recorded in the MoH registration records were significantly higher (sometimes more than double) than the police-reported ones. It should be noted here that road crashes cause up to 4.7% of all mortalities in Saudi Arabia, while they cause less than 1.7% in many developed countries, like Australia, the UK, and the US [1, 9, 38, 69].

In addition to human losses, road traffic crashes cause enormous economic losses. No comprehensive and accurate study has been conducted to determine economic losses due to traffic crashes in Saudi Arabia. All previous studies that tried to estimate economic losses due to MVCs in KSA were based on models used in developed countries (like the UK and USA) [6, 10, 53, 70-72]. These estimates ranged between US$0.53 billion [71] and US$16 billion [72]. It is believed that such large discrepancies in the loss estimates are caused mainly by differences in the estimated average wages, medical costs, crash vehicle repair costs, and others.

A detailed study worth mentioning in this regard is the one done by ADA using the concept of a ‘Gross Output.’ This study found that road crashes in KSA cost approximately US$ 6.73 billion annually [18]. Costs have been calculated using resource costs with amounts added for ‘Pain, Grief, and Suffering’, followed by adding ‘Human’ costs assessed by what is known as ‘Willingness to Pay’ (WTP) approach.

Post-impact care is an essential topic for reducing the severity of injury consequences when a traffic crash occurs [73]. Post-impact care includes actions of the injured person at the crash scene, help by bystanders, access to emergency facilities, intervention provided by ambulance officers and paramedics at the scene or while being transported to the hospital, hospital trauma care and availability to rehabilitation services [74]. Post-impact care has shown some weaknesses in KSA. The coverage of emergency medical services and trauma care was found to be relatively weak and disorganized when compared to the corresponding services in developed countries with similar land size. Officially, transferring people with traffic-related injuries to hospitals in Saudi Arabia should be done by Saudi Red Crescent Society (SRCS) ambulances [75]. Nevertheless, it is reported that only 67% of road crash victims in KSA are transported to hospitals by ambulances, 25% by regular motor vehicles, and 8% by airlifting [50]. Moreover, it is stated that scarcity of trained staff and field paramedics, underserved medical facilities, and shortage of adequate equipment are the main contributing factors to the high mortalities and disabilities rates due to MVCs in KSA [77].

As also identified by Mulat et al. [78], there are significant discrepancies in estimating the number of fatalities at the crash scene as well as before and after being admitted to the hospital due to road crashes across Saudi Arabia. For example, Badawi et al. [79] reported that only 12% of all traffic-related deaths were reported in the Asir region before being admitted to hospital while Khawashki [80] stated that 64-70% in the Riyadh region died before being admitted.

Another study by Ali et al. [81] reported that 40% of traffic-related deaths were recorded during the first 24 hours after the crash. Al-Ghamdi [82] found that out of 138 deaths from traffic crashes in the Riyadh area during the years of 1994-1996, 45% died within the first 24 hours after being admitted to hospital, and 95% died within 30 days after the crash. Al-Shammari et al. [50] showed that of the 1,800 fatally injured persons due to crashes in Riyadh during 2005, 63% died before being admitted to hospital. Their results also showed that 84% died in intensive care units within the first 24 hours after admission.

Although several factors play an important role in the outcome of any road crash-related injury, the above-mentioned pre- and post-hospital admission death rates are considered high when compared to developed countries [14, 33, 45, 83]. Specifically, the ambulance response time in the Riyadh region has been identified to be below the standards, which are commonly practiced in developed nations, like the UK and the USA [50, 56, 77]. All the studies that have investigated the direct and/or indirect performance of the emergency rescue system in Saudi Arabia concluded that there is an imperative need to improve the quality of this system [17, 50, 57, 77, 80, 81].

Upper and lower extremities represent the most common injuries (31-38%) due to MVCs in Saudi Arabia [6, 60, 71]. Although extremity injuries due to road crashes are generally not life-threatening, they constitute a major cause of disability. Out of all those who are injured annually due to road crashes in KSA, 6 to 7% of them are discharged with residual disabilities [7]. In 2005, it was reported that 627 people lost their extremities because of road crashes in the country [21]. Other studies showed that the most common disability due to MVCs in KSA is amputation of limbs - arms or legs [45, 71, 84, 85].

The average length of stay at the hospital in KSA is estimated to be 10 to 13 days [82, 84]. It was also reported that the total number of beds operated by 274 MoH hospitals around the country was 41,835 in 2015. One-third of these beds are occupied by patients injured in road crashes [21]. Specifically, MVCs were the direct cause of 73.6% of all hemiplegia, paraplegia, and tetraplegia cases in KSA [53]. Moreover, it was reported that head (22-35%) and spine (5-9%) were the most common fatal injuries among road crash victims, both of which usually require long stays in hospitals [71, 82, 84]. Such figures put a strain on the medical system and deprive the country of vital medical resources [85].