The City of...
Studies try to break down reasons behind adolescent crashes
Over the past decades, the population of young drivers has been continuously decreasing
Over the past decades, the population of young drivers has been continuously decreasing. In 1970, drivers between the ages of 15-20 accounted for 11.7% of the U.S. driving population. It was 6.8% in 1998.
Despite this decrease, the crash rate of younger drivers has increased during the last decade, and they were involved in more fatal accidents than any other age group.
Significant research has been completed investigating the disproportionate number of younger drivers in single vehicle crashes when compared to older drivers, because such crashes remain to be the No. 1 fatal crash for this age group. Speeding is another frequent cause of crashes for drivers 18-24 years old, with the highest speed observed for drivers under 20 years of age. Largely due to the increase in speed, youths have a greater frequency citing loss of control as the primary reason of a crash (28.5%) as compared to older drivers (16.9%).
While past research has shown mixed results regarding the significance of rear-end collisions among young drivers, the majority of findings support an increased crash propensity. Their increased likelihood to be involved in rear-end crashes was attributed to their greater confidence of driving at higher speeds and following vehicles closer. At the same time their awareness of the situation decreased.
Another area of concern for young drivers has involved movements at intersections, especially turning left into oncoming traffic. The problem, however, seems to have different reasons depending on gender. Studies show young female have been involved in more collisions at intersections than males. In relation to these incidents, a gender-related difference in visual perception was cited, demonstrating problems females have with spatial perception and orientation.
Nighttime driving and vehicle occupancy were other crash factors involving youths. Theres a higher risk of crash at night than during the day, but this risk was even more pronounced for young drivers, particularly on Friday and Saturday nights. This was especially troublesome considering the fact young drivers had the lowest travel distance of all groups studied.
Even more alarming is the effect vehicle occupancy has among young drivers. For older age groups, increased passenger occupancy decreased the likelihood of a crash. However, increased passenger occupancy in-creased the likelihood of crashes of drivers 16 to 19 years old, with a dramatic increased risk when there are three or more passengers in a car. Young drivers were two times as likely to be involved in a crash when there was one or more passengers, and 16- and 19-year-old males remained to be the population at greatest risk in all categories. In a study of Swedish young drivers, risky driving (i.e., speeding and dangerous maneuvering) was shown to coincide with the fact that peer and societal pressures made younger drivers feel the need to engage in these types of activities. Peer pressure is obviously more pronounced when there is a high peer occupancy rate, and it increases significantly in the presence of passengers.
In an attempt to better understand this issue, databases (1994-1996) for the Commonwealth of Kentucky were examined.
The most impact
Four main types of crashes have been identified as having either high or questionable involvement of young drivers. From past research, it also is evident that there may exist different causal factors (time of day, number of occupants, driver gender) for each of the four types of crashes.
Past research shows there is a higher risk in making left-turning movements at intersections as compared to other intersection movements due to crossing two directions of traffic and estimating speeds of oncoming traffic. Therefore, by examining this movement it is possible to define factors in the driving characteristics of young people to better understand their higher propensity for crash occurrence at intersections.
Left-turn movements were defined to be any crash taking place at an intersection where the at-fault driver/vehicle was completing a left-turning movement on a roadway consisting of two or more lanes. No differentiation was taken into account for the presence of turning lanes or for the type of operating traffic control devices at the intersection, since this information was not available from the crash data. The possible influencing factors of age, gender, occupancy rates and period of the day were examined for this movement.
Definite conclusions can be drawn from the effect of age on the crash propensity of younger drivers. Data shows a general trend of decreasing crash involvement as the driver ages. However, within this trend a sharp decrease can be seen between the ages of 16 and 17, while after the age of 17 this decrease is dramatically slowed. From this data, it is then reasonable to conclude that crash likelihood decreases rapidly within the first few years of driving. The cause for this decrease is unclear. It could correspond to an increased experience level of the driver by enhancing ones ability to control the vehicle and perfecting visual search patterns or could arise from an increased maturity level, which would reduce the risky behavior of young drivers. A comparison between these drivers to ones over 20 years of age indicates that younger drivers exhibit higher rates than the remaining population.
While previous research findings showed that the female driving population was at a greater risk than the male population, this study found no statistical difference between genders. Another factor examined was the period of day when the crash occurred. The statistical analysis showed no significant difference between day and night crashes. This is especially surprising considering the higher volume of traffic likely to be present during daytime hours.
This could possibly be explained by the operational characteristics of these movements. The vehicle at greater risk would be the first in line, since it would initiate a left-turning movement into oncoming traffic. However, in times of high traffic volumes, left-turning vehicles would most likely move in queues and thus there is a decreased risk for vehicles in the middle of the queue. At nighttime, due to lower volumes of traffic, the likelihood of being the initiating vehicle is greater. This added risk of nighttime driving could be offset by the lower volume of traffic when compared to that of the high volume of daytime traffic.
Finally, the effect of occupancy rates was examined and no statistically significant differences were noted in the overall group of young drivers nor when split by age categories. Therefore, the overall contributing factor to the increased involvement of youth in left-turn crashes at intersections may be shown to be influenced more heavily by perception tasks as well as their ability to control the vehicle.
Rear-end crashes were looked at because it has been hypothesized that the reason for a higher incidence of youth drivers in rear-end crashes is due to a feeling of greater confidence driving at higher speeds and following with shorter gaps.
First, the factor of driver age was examined, which was determined to be of statistical significance. A continuous decline of the rear-end crash involvement for all age groups was noted. This trend is significant because it demonstrates a continuous trend of safer driving throughout all five years of age. Thus, the reason for the decline should be based on a model of a more gradual and longer learning curve than that of the intersection crash model. However, these drivers still show higher rates compared to drivers over 20 years old.
The data showed males having higher involvement ratios than femalesa statistically significant result. However, when the populations were further divided and studied by both age and gender there is no significant difference in crash involvement between the genders of the same age group.
The statistical analysis for the time of day showed that night ratios are higher than those of the day. When age is considered statistical difference was only found for the 16-, 17- and 18-year-old age groups. Also, when the raw data is examined it is found that approximately 84% of all rear-end crashes in which youth were involved occurred during daytime hours. This was somewhat expected, since the major volume of traffic is present during the day. It would be expected that higher volumes of traffic also would contribute to a higher crash involvement rate due to the added congestion. However, the rates of the young drivers reflect an increased involvement during the nighttime with lower traffic volumes. The increased involvement of the drivers at night is a result of motivational factors and not an experience-related behavior. This trend decreases during the ages of 19 and 20, perhaps demonstrating increased maturity of the driver.
Another type of maneuver in which youths are said to have a higher incidence rate is that of head-on collisions caused when the driver attempts to pass or overtake other cars. In this study passing on two-lane, two-way roads was examined.
The same decreasing trend with age is evident as that observed in rear-end and intersection crashes: there is a decreasing trend with increasing age which is statistically significant, but theres also a higher general rate when compared to drivers over 20 years old. The dramatic reduction in the crashes after the initial year of driving between 16 and 17 may be demonstrative of the potential presence of a sharp learning curve within the first few years of driving.
Male drivers have much higher involvement rates in passing crashes than female drivers. When subdivided further into age categories, some interesting observations can be made.
First, there seems to be a rather sizable difference between male and female drivers in the first year of driving, with males having higher involvement rates than females. It appears young males view themselves as much more skilled drivers and have higher confidence levels than females. However, between the ages of 17 and 19 female drivers actually show a higher involvement than males. This could be explained by the hypothesis of females being more comfortable behind the wheel at these ages and thus engage in riskier activity.
The analysis of the effect of occupants on crash involvement showed no significance in terms of occupancy rates. This is especially surprising due to the fact that the crashes resulting from a passing maneuver are most often thought to result from motivational factors and the belief that increased peer occupancy rates increase the tendency to participate in risky behavior.
Single vehicle crashing
Perhaps one of the most troubling of all crashes studied is that of the single vehicle crash due to its high frequency of occurrence among young drivers and the higher severity levels resulting from such a crash. A contributing factor may be inattention of the driver, causing him/her to run off the road and crash.
There was a decreasing trend of crash propensity with age, and data clearly shows that after the first year of driving there is a dramatic decrease in the involvement rates of young drivers. This may be indicative of a sharp learning curve or of a sharp decrease in motivational factors placing the drivers at risk.
Again, males have much higher involvement rates than females. However, when broken down by age and gender a new trend appears. Females in the 17- and 18-year-old age groups have a higher involvement in single vehicle crashes than males. In fact, the statistical analysis showed significance only for the age group of 17 years, where females have a higher involvement rate than males. This finding may indicate a different maturing period between genders, where males may curb their risk-taking behavior after their first year of driving. The difference also may reflect a different starting point in driving behavior, where females start driving more frequently at a later age than males.
The only major factor found to significantly contribute to crash involvement while conducting left turns was that of the drivers age. This information lends itself to the possibility that left-turning movements exhibit a crash characteristic affected mainly by the ability of the driver to handle the demands of maneuvering a vehicle through traffic. This factor is consistent with the trend of decreasing crashes with increasing age since drivers gain experience with the passing of time.
From the data analyzed for rear-end crashes there still exist many questions about the real cause and true characteristics of youth rear-end crash involvement. While the general trend of decreasing involvement is coupled with increasing age, it is unclear as to whether ability, experience or maturity govern youth involvement in this type of crash.
While it is obvious motivational factors are responsible for the initial engagement and decision to pass another vehicle, they may not be responsible for the final execution of the maneuver. If motivational factors were responsible for increasing crash involvement, it would be expected that increased occupancy would further increase the risk by escalating the motivational factors. Due to the absence of this effect it may be seen that during such a maneuver the driver will act responsibly within the limits of their perceived ability. This is evident in the gender-related difference among 16-year-old drivers. Therefore, the cause of the crash may be more reliant on the perception ability of drivers to differentiate between safe and unsafe passing conditions.
The traditional understanding of youth single vehicle crashes does not easily compare to the findings of this study. While involvement was found to decrease with age, no other factor examined was found to be consistent with the previous research. New drivers, 16 and 17 years old, were found to have a higher involvement in single vehicle crashes during daytime than during the night. While this may be affected by stricter driving limitations imposed on youths by factors other than licensing requirements, it is largely inconsistent with the belief that the prime time for single vehicle crashes is during nighttime periods. Single vehicle crashes also are believed to be a male-dominated crash. However, after the initial year of driving females are shown to actually have a higher involvement rate than males.
Through examination of all crash types there is a general trend of safer driving with increasing age. The important finding is that the higher crash involvement is due to the lack of experience and maturity among young drivers. Therefore, little can be done to improve this phenomenon. Increasing the level of awareness among young drivers about these issues and their likely crash involvement seems to be the only viable approach.