Although nighttime riding is considered a risk factor for ATV crash, relatively few studies have provided data on the nighttime use of ATVs and resulting injuries. We found that approximately one-fourth of ATV crashes occurred at night. Other studies have found similar proportions. About one-third of ATV-related fatalities documented in Ontario coroner reports from 1996-2005 (N=74) occurred after dusk and before dawn [8]. Of 481 ATV crash victims presenting to the University of Mississippi Medical Center from 2005-2010, 27% of the crashes occurred between 8 pm and 6 am [9]. A newspaper clippings study of off-road vehicle crashes in nine Great Plains states (N=1,019) found that 38% of ATV crashes had occurred in compromised light conditions (dusk, night, dawn) [11]. In addition, a study of U.S. roadway ATV fatalities utilizing the Fatality Analysis Reporting System (FARS) revealed 28% occurred from 9 pm-6 am [10].
Demographics of nighttime crashes
About one-quarter of all males and females were injured in nighttime crashes. Although a West Virginia study reported males having a higher proportion of crashes at night (30%) as compared to females (14%), this difference was not statistically significant [19]. With respect to age in our study, the proportion of nighttime crashes was significantly higher for adults (29%) than for youth (13%). Previous research on ROVs also found adults to have a higher percentage of crashes at night as compared to youth. Specifically, ~40% of adult ROV crash victims were injured at night as compared to 0% of youth victims treated at the University of Iowa and 17% of youth in press clippings of ROV crashes in nine Great Plains states, p=0.004 [11, 20]. Our observed proportion of youth injured at night was also similar to the 16% of pediatric nighttime victims seen in a previous multi-institutional study [12].
Our study also showed that higher proportions of female and adult passenger victims were seen in nighttime as compared to daytime crashes. In contrast, there were no differences in the proportion of ATV passenger victims when comparing crashes occurring during the day and at night for ED patients evaluated at the University of Iowa [17]. This difference may reflect the broader sampling of crashes and injuries in our statewide database.
Helmet use was lower at night than during the day. Limited helmet use has been reported in numerous studies, including lower use by females as compared to males and adults versus youth [21, 22]. This is the first study to report a difference in helmet use between daytime and nighttime crashes.
Alcohol use
We found that adult victims in ATV crashes occurring at night more frequently tested positive for alcohol than victims in daytime crashes (44% vs 13% of those tested). A small number of youth victims tested positive, and the proportion positive was not different by day versus night. Other studies also found a significantly higher proportion of alcohol use among ATV crash victims at night as compared to during the day. At the University of Mississippi, nearly one-half (46%) of nighttime crash victims were alcohol intoxicated while about one-fifth (22%) were positive during daylight hours [9]. Similarly, 52% of nighttime ATV crashes were alcohol-related as compared to 19% during the day for ED patients seen at the University of West Virginia [19]. Alcohol intoxication has been found to be an independent risk factor for serious ATV-related injury [9], including maxillofacial [19] and spinal injuries [23].
Seasonality and day of the week
Nighttime crash victims were more common in fall and winter as compared to daytime crash victims that were also of higher frequency in spring and summer. We speculate this may reflect similar evening riding habits combined with shorter days in the fall and winter. The most common nights for ATV-related injuries in our study were Saturday and Sunday. The University of West Virginia similarly found Saturday to be the most frequent day of the week for nighttime ATV crashes [19].
Crash location
Overall, a higher proportion of roadway crash victims was seen at night and injuries occurred on both paved and unpaved surfaces. Previous studies showed that riding on the road is an independent risk factor for deaths and serious injury and that injury severity was higher for both paved and unpaved roads relative to off-road terrains [15, 21, 24].
Crash mechanism
Injuries from ATV-ATV collisions were more frequent at night, whereas those from collisions with other motor vehicles were less frequent. This was true for males, youth, and adult victims. We speculate that limited light conditions and visibility may contribute to the higher frequency of ATV-ATV collisions when riding in groups and that the lower frequency of collisions with other motor vehicles may reflect less traffic at night. As previously observed [5, 15, 18, 21, 24], the major crash mechanism in all cases was a non-collision event, i.e., a rollover. A study of ATV-related spinal injuries noted rollovers to be a frequent injury mechanism of their nighttime patients [23].
Injury mechanism and outcome
Two-thirds of nighttime and daytime crash-related injuries involved falling from or being ejected from the vehicle. Conversely, being hit or pinned by the vehicle was less frequently observed at night (17%) than during the day (26%). The basis for this difference remains to be determined. An earlier study reported that the percentage of crush-related injuries (e.g. compression asphyxia) in fatal ATV crashes had increased over time [21]. As ATVs have increased in size and weight, the ability of riders to self-eject or clear the vehicle during a mishap has decreased leading to a greater likelihood of being hit or pinned.
We did not find differences in brain injuries or trauma severity when comparing nighttime and daytime crash victims despite differences in alcohol use and injury mechanism. Additional studies may be needed, as documentation of light conditions was highly limited in the STR, the primary source of injury data. In contrast, a regression analysis of snowmobile-related deaths found fatalities to be about twice as likely during times of sub-optimal lighting as compared to daylight hours [25].
Prevention
Our study builds on previous knowledge in the field, particularly on the limited studies related to light conditions, and provides support for the recommendations that driving ATVs at night by adults should only be done with extreme caution and avoided if at all possible. Youth have been shown to be a particularly vulnerable ATV population and should never be riding ATVs at night.
Among strategies that could reduce deaths and injuries, including among riders who choose nighttime riding are improvements in ATV design [26]. These would include brighter lights on adult-size vehicles [8]. Moreover, because the vast majority of pediatric deaths and injuries occur with adult-size vehicles, design changes, like seat design, that discourage youth riding would be of value and could prevent riding of these vehicles both at night and during the day [27]. Promising results have also been seen in studies of crush protection devices that prevent or reduce the severity of being hit/pinned by the ATV [28, 29].
One of the most effective prevention strategies is passage and enforcement of safety laws. Whereas many states have ATV-related legislation to address safety concerns, state laws vary considerably [30], and prohibiting nighttime riding is not universal. In addition, an increasing number of states and counties are opening roadways to recreational ORV use and a daylight restriction is often not included [31]. Safety experts, including the Consumer Federation of America, recommend a ban on nighttime riding, including on the road [31, 32].
Limitations
These studies have the limitations inherent in retrospective research and those experienced by other ATV injury prevention researchers. These include incomplete capture of crash and injury records and/or incomplete variable documentation including time of crash and light conditions. In addition, data sources used in this study are more likely to record moderate to severe crashes and injuries, rather than crashes resulting in injuries not needing medical attention or only requiring medical care in an outpatient setting. Moreover, because of limitations in available information, some side-by-side vehicles may have been documented as ATVs and included in the study. However, we hypothesize that this would not significantly bias results, as identified side-by-sides only comprised 9% (367/4292) of cases in our database. Despite these limitations, many of our findings are similar to other reports related to nighttime versus daytime crashes and they build on the highly limited information currently available for this topic.