Association between driver and child passenger restraint: Analysis of community-based observational survey data from 2005 to 2019

Introduction: Crash data suggest an association between driver seatbelt use and child passenger restraint. However, community-based restraint use is largely unknown. We examined the association between driver seatbelt use and child restraint using data from a state-wide observational study. Methods: Data from Iowa Child Passenger Restraint Survey, a representative state-wide survey of adult seat belt use and child passenger safety, were analyzed. A total of 44,996 child passengers age 0–17 years were observed from 2005 to 2019. Information about driver seatbelt use and child restraint was directly observed by surveyors and driver age was reported. Logistic regression was used to examine the association between driver seatbelt use and child restraint adjusting for vehicle type, community size, child seating position, child passenger age, and year. Results: Over the 15-year study period, 4,114 (9.1%) drivers were unbelted, 3,692 (8.2%) children were completely unrestrained, and another 1,601 (3.6%) children were improperly restrained (analyzed as unrestrained). About half of unbelted drivers had their child passengers unrestrained (51.8%), while nearly all belted drivers had their child passengers properly restrained (92.3%). Compared with belted drivers, unbelted drivers had an 11-fold increased odds of driving an unrestrained child passenger (OR = 11.19, 95%CI = 10.36, 12.09). The association between driver seatbelt use and child restraint was much stronger among teenage drivers. Unbelted teenage drivers were 33-fold more likely (OR = 33.34, 95%CI = 21.11, 52.64) to have an unrestrained child passenger. Conclusion: These data suggest that efforts to increase driver seatbelt use may also have the added benefit of increasing child restraint use. Practical applications: Enforcement of child passenger laws and existing education programs for new drivers could be leveraged to increase awareness of the benefits of seatbelt use for both drivers themselves and their occupants. Interventions aimed at rural parents could emphasize the importance of child safety restraints.     

Vehicle characteristics associated with LATCH use and correct use in real-world child restraint installations

IntroductionThe objective of this study was to determine if vehicle features associated with LATCH ease-of-use in laboratory studies with volunteers predict LATCH use and misuse in real-world child restraint installations.MethodVehicle characteristics were extracted from prior surveys of more than 100 top-selling 2010–13 vehicles. Use and correct use of LATCH was determined from records of more than 14,000 child restraint installations in these vehicles that were inspected by child passenger safety technicians at Safe Kids car seat checkup events during 2010–12. Logistic regression was used to examine the association between vehicle features and use and correct use of lower anchors and top tethers, controlling for other relevant installation features.ResultsLower anchors were more likely to be used and correctly used when the clearance angle around them was greater than 54°, the force required to attach them to the lower anchors was less than 178 N, and their depth within the seat bight was less than 4 cm. Restraints were more likely to be attached correctly when installed with the lower anchors than with the seat belt. After controlling for lower anchor use and other installation features, the likelihood of tether use and correct use in installations of forward-facing restraints was significantly higher when there was no hardware present that could potentially be confused with the tether anchor or when the tether anchor was located on the rear deck, which is typical in sedans.ConclusionsThere is converging evidence from laboratory studies with volunteers and real-world child restraint installations that vehicle features are associated with correct LATCH use.Practical applicationsVehicle designs that improve the ease of installing child restraints with LATCH could improve LATCH use rates and reduce child restraint misuse.     

Investigation of Child Restraint System (CRS) Compatibility in the Vehicle Seat Environment

Objective: Child restraint system (CRS) misuse is common and can have serious consequences to child safety. Physical incompatibilities between CRS and vehicles can complicate the installation process and may worsen CRS misuse rates. This study aims to identify the most common sources of incompatibility between representative groups of CRS and vehicles.

Methods: Detailed dimensional data were collected from 59 currently marketed CRS and 61 late model vehicles. Key dimensions were compared across all 3,599 theoretical CRS/vehicle combinations and the most common predicted incompatibilities were determined. A subset of 34 physical installations was analyzed to validate the results.

Results: Only 58.2% of rear-facing (RF) CRS/vehicle combinations were predicted to have proper agreement between the vehicle's seat pan angle and the CRS manufacturers’ required base angle. The width of the base of the CRS was predicted to fit snugly between the vehicle's seat pan bolsters in 63.3% of RF CRS/vehicle combinations and 62.2% of forward-facing (FF) CRS/vehicle combinations. FF CRS were predicted to be free of interaction with the vehicle's head restraint in 66.4% of combinations. Roughly 90.0% of RF CRS/vehicle combinations were predicted to have enough horizontal clearance space to set the front seat in the middle its fore/aft slider track. Compatibility rates were above 98% regarding the length of the CRS base compared to the length of the vehicle seat pan and the ability of the top tether to reach the tether anchor. Validation studies revealed that the predictions of RF CRS base angle range vs. seat pan angle compatibility were accurate within 6%, and head restraint interference and front row clearance incompatibilities may be more common than the dimensional analysis approach has predicted.

Conclusions: The results of this study indicate that RF CRS base angles and front row clearance space, as well as FF CRS head restraint interference, are frequent compatibility concerns. These results enable manufacturers, researchers, and consumers to focus their attention on the most relevant CRS/vehicle incompatibility issues in today's market.     

Association Between NCAP Ratings and Real-World Rear Seat Occupant Risk of Injury

Objective: Several studies have evaluated the correlation between U.S. or Euro New Car Assessment Program (NCAP) ratings and injury risk to front seat occupants, in particular driver injuries. Conversely, little is known about whether NCAP 5-star ratings predict real-world risk of injury to restrained rear seat occupants. The NHTSA has identified rear seat occupant protection as a specific area under consideration for improvements to its NCAP. In order to inform NHTSA's efforts, we examined how NCAP's current 5-star rating system predicts risk of moderate or greater injury among restrained rear seat occupants in real-world crashes.

Methods: We identified crash-involved vehicles, model year 2004–2013, in NASS-CDS (2003–2012) with known make and model and nonmissing occupant information. We manually matched these vehicles to their NCAP star ratings using data on make, model, model year, body type, and other identifying information. The resultant linked NASS-CDS and NCAP database was analyzed to examine associations between vehicle ratings and rear seat occupant injury risk; risk to front seat occupants was also estimated for comparison. Data were limited to restrained occupants and occupant injuries were defined as any injury with a maximum Abbreviated Injury Scale (AIS) score of 2 or greater.

Results: We linked 95% of vehicles in NASS-CDS to a specific vehicle in NCAP. The 18,218 vehicles represented an estimated 6 million vehicles with over 9 million occupants. Rear seat passengers accounted for 12.4% of restrained occupants. The risk of injury in all crashes for restrained rear seat occupants was lower in vehicles with a 5-star driver rating in frontal impact tests (1.4%) than with 4 or fewer stars (2.6%, P =.015); results were similar for the frontal impact passenger rating (1.3% vs. 2.4%, P =.024). Conversely, side impact driver and passenger crash tests were not associated with rear seat occupant injury risk (driver test: 1.7% for 5-star vs. 1.8% for 1–4 stars; passenger test: 1.6% for 5 stars vs 1.8% for 1–4 stars).

Conclusions: Current frontal impact test procedures provide some degree of discrimination in real-world rear seat injury risk among vehicles with 5 compared to fewer than 5 stars. However, there is no evidence that vehicles with a 5-star side impact passenger rating, which is the only crash test procedure to include an anthropomorphic test dummy (ATD) in the rear, demonstrate lower risks of injury in the rear than vehicles with fewer than 5 stars. These results support prioritizing modifications to the NCAP program that specifically evaluate rear seat injury risk to restrained occupants of all ages.     

Characteristics of rear-end crashes involving passenger vehicles with automatic emergency braking

Abstract

Objectives: Automatic emergency braking (AEB) is a proven effective countermeasure for preventing front-to-rear crashes, but it has not yet fully lived up to its estimated potential. This study identified the types of rear-end crashes in which striking vehicles with AEB are overrepresented to determine whether the system is more effective in some situations than in others, so that additional opportunities for increasing AEB effectiveness might be explored.

Methods: Rear-end crash involvements were extracted from 23?U.S. states during 2009–2016 for striking passenger vehicles with and without AEB among models where the system was optional. Logistic regression was used to examine the odds that rear-end crashes with various characteristics involved a striking vehicle with AEB, controlling for driver and vehicle features.

Results: Striking vehicles were significantly more likely to have AEB in crashes where the striking vehicle was turning relative to when it was moving straight (odds ratio [OR]?=?2.35; 95% confidence interval [CI], 1.76, 3.13); when the struck vehicle was turning (OR = 1.66; 95% CI, 1.25, 2.21) or changing lanes (OR = 2.05; 95% CI, 1.13, 3.72) relative to when it was slowing or stopped; when the struck vehicle was not a passenger vehicle or was a special use vehicle relative to a car (OR = 1.61; 95% CI, 1.01, 2.55); on snowy or icy roads relative to dry roads (OR = 1.83; 95% CI, 1.16, 2.86); or on roads with speed limits of 70+ mph relative to those with 40 to 45?mph speed limits (OR = 1.49; 95% CI, 1.10, 2.03). Overall, 25.3% of crashes where the striking vehicle had AEB had at least one of these overrepresented characteristics, compared with 15.9% of strikes by vehicles without AEB.

Conclusions: The typical rear-end crash occurs when 2 passenger vehicles are proceeding in line, on a dry road, and at lower speeds. Because atypical crash circumstances are overrepresented among rear-end crashes by striking vehicles with AEB, it appears that the system is doing a better job of preventing the more typical crash scenario. Consumer information testing programs of AEB use a test configuration that models the typical rear-end crash type. Testing programs promoting good AEB performance in crash circumstances where vehicles with AEB are overrepresented could guide future development of AEB systems that perform well in these additional rear-end collision scenarios.     

Field effectiveness evaluation of advanced driver assistance systems

Abstract

Objective: Advanced driver assistance systems (ADAS) are a class of vehicle technologies designed to increase safety by providing drivers with timely warnings and autonomously intervening to avoid hazardous situations. Though laboratory testing suggests that ADAS technologies will greatly impact crash involvement rates, real-world evidence that characterizes their effectiveness is still limited. This study evaluates and quantifies the association of ADAS technologies with the likelihood of a moderate or severe crash for new-model BMWs in the United States.

Methods: Vehicle ADAS option information for the cohort of model year 2014 and later BMW passenger vehicles sold after January 1, 2014 (n?=?1,063,503), was coded using VIN-identified options data. ADAS technologies of interest include frontal collision warning with autonomous emergency braking, lane departure warning, and blind spot detection. BMW Automated Crash Notification system data (from January 2014 to November 2017) were merged with vehicle data by VIN to identify crashed vehicles (n?=?15,507), including date, crash severity (delta V), and area of impact. Using Cox proportional hazards regression modeling, the study calculates the adjusted hazard ratio for crashing among BMW passenger vehicles with versus without ADAS technologies. The adjusted percentage reduction in moderate and severe crashes associated with ADAS is interpreted as one minus the hazard ratio.

Results: Vehicles equipped with both autonomous emergency braking and lane departure warning were 23% less likely to crash than those not equipped (hazard ratio [HR]?=?0.77; 95% confidence interval [CI], 0.73–0.81), controlling for model year, vehicle size and body type. Autonomous emergency braking and lane departure warning generally occur together, making it difficult to tease apart their individual effects. Blind spot detection was associated with a 14% reduction in crashes after controlling for the presence of autonomous emergency braking and lane departure warning (HR =0.86; 95% CI, 0.744–0.99). Differences were observed by vehicle type and crash type. The combined effect of autonomous emergency braking and lane departure warning was greater in newer model vehicles: Equipped vehicles were 13% less likely to crash (HR =0.87; 95% CI, 0.79–0.95) among 2014 model year vehicles versus 34% less likely to crash (HR =0.66; 95% CI, 0.57–0.77) among 2017 model year vehicles.

Conclusion: This robust cohort study contributes to the growing evidence on the effectiveness of ADAS technologies.     

Trends in aggressivity and driver risk for cars,SUVs, and pickups: Vehicle incompatibility from 1989 to 2016

Abstract

Objective: When 2 vehicles of different sizes collide, the occupants of the smaller vehicle are more likely to be injured than the occupants of the larger vehicle. The larger vehicle is both more protective of its own occupants and more aggressive toward occupants of the other vehicle. However, larger, heavier vehicles tend to be designed in ways that amplify their incompatibility with smaller, lighter vehicles (by having a higher ride height, for example). A 2012 study by the Insurance Institute for Highway Safety (IIHS) concluded that fatalities caused by design incompatibility have decreased in recent years. The current study was conducted to update the 2012 IIHS analysis and to explore trends in vehicle incompatibility over time.

Methods: Analyses examined deaths in crashes involving 1- to 4-year-old passenger vehicles from 1989 to 2016 collected from the Fatality Analysis Reporting System (FARS). Trends in driver risk were examined by comparing driver death rates per million registered vehicle years across vehicle type and size. Trends in aggressivity were examined by comparing partner driver death rates across vehicle type and size.

Results: Cars and SUVs have continued their trend toward reduced incompatibility. In 1989–1992, SUVs were 132% more likely to kill the driver in a partner car compared with when a car crashed with another car. By 2013–2016, this value had dropped to 28%. Pickups and cars remain just as incompatible in 2013–2016 as they were in 1989–1992, however (159% vs. 158%). Remaining pickup incompatibility may be largely due to excess curb weight rather than to shape or design features, because light pickups were just 23% more likely to kill the driver in a partner car compared with when a car crashed with another car.

Conclusions: The trend toward reduced fleet incompatibility has continued in the latest crash data, particularly for cars and SUVs. Although pickup–car incompatibility has also decreased over time, pickups remain disproportionately aggressive toward other vehicles, possibly due to their greater average curb weight. Reducing the weight of some of the heaviest vehicles and making crash avoidance technology fitment more widespread may be promising means to reduce remaining fleet incompatibility. Identifying the source of remaining incompatibility will be important for safety improvements going forward.     

Effects of LATCH versus Available Seatbelt Installation of Rear Facing Child Restraint Systems on Head Injury Criteria for 6 Month Old Infants in Rear End Collisions

Objective: The Lower Anchor and Tethers for CHildren (LATCH) system was introduced in vehicles made after September 1, 2002 and intended to make installation of rear and forward-facing child safety seats easier. Due to the lack of rear impact testing of RFCRS required per the Federal Motor Vehicle Safety Standards (FMVSS), the purpose of this study was to explore the effects, if any, of installation method of RFCRS on the performance of commonly purchased makes and models of RFCRS. Specifically, we hypothesize that in a 48 km/h (29.8 MPH) rear-end collision, installation of RFCRS using the LATCH system will result in higher Head Injury Criteria (HIC) values when compared to using the available lap/shoulder seatbelt (Emergency Locking Retractor - ELR or Automatic Locking Retractor - ALR).

Methods: The test matrix included 36 rear impact sled tests conducted using 3 installation methods on 3 models of RFCRS: the Graco SnugRide® with and without the base, the Britax Chaperone with base-mounted anti-rebound bar, and the Evenflo Tribute®, a model of convertible rearward/forward facing restraint system used in the rearward facing mode. The seats were installed using the LATCH system, ELR lap/shoulder belts, or ALR lap/shoulder belts in seating positions 4 and 6 on a vehicle buck mounted to the sled test base. The infant seat and 6 month old CRABI anthropometric test device (ATD) installation methods were in accordance with standards set forth in the National Highway Traffic Safety Administration's (NHTSA) FMVSS No. 213, Child Restraint Systems. All tests were conducted on pneumatic controlled acceleration sled (HYGE, Inc., PA, USA) at 48 km/h.

Results: Installation of infant seat type RFCRS using the LATCH system resulted in higher HIC₁₅ values when compared to using the available lap/shoulder seatbelt (ELR or ALR). The mean HIC₁₅ values were most severe when infant seat type RFCRS were installed using LATCH (Graco SnugRide® HIC₁₅ = 394 and Britax Chaperone HIC₁₅ = 133) compared to using either ELR lap/shoulder belts (Graco SnugRide® HIC₁₅ = 218 and Britax Chaperone HIC₁₅ = 65) or ALR lap/shoulder belts (Graco SnugRide® HIC₁₅ = 194 and Britax Chaperone HIC₁₅ = 78). The installation method did not result in a statistically significant difference in HIC for the convertible type RFCRS (Evenflo Tribute®). In many of the tests, the ATD's head struck the seatback in which the RFCRS was installed. These head strikes resulted in the higher HIC₁₅ scores recorded throughout the testing.

Conclusions: The results of this study suggest that LATCH does not offer equal protection to lap/shoulder belts from head injuries in rear impacts when used with infant seat type RFCRS.     

Vehicle choices for teenage drivers: A national survey of U.S. parents

IntroductionPrevious research has shown that many newly licensed teenagers in the United States are driving vehicles with inferior crash protection. The objective of this study was to update and extend previous research on U.S. parents' choices of vehicles for their teenagers.MethodTelephone surveys were conducted with parents in May 2014 using a random sample of U.S. households likely to include teenagers. Participation was restricted to parents or guardians of teenagers who lived in the household and held either an intermediate or full driver's license. Parents were interviewed about the vehicle their teenager drives, the reason they chose the vehicle for their teenager, and the cost of purchased vehicles.ResultsTeenagers most often were driving 2000–06 model year vehicles (41%), with 30% driving a more recent model year and 19% driving an older model year. Teenagers most often were driving midsize or large cars (27%), followed by SUVs (22%), mini or small cars (20%), and pickups (14%). Far fewer were driving minivans (6%) or sports cars (1%). Forty-three percent of the vehicles driven by teenagers were purchased when the teenager started driving or later. A large majority (83%) were used vehicles. The median cost of the vehicles purchased was $5300, and the mean purchase price was $9751.ConclusionsAlthough parents report that the majority of teenagers are driving midsize or larger vehicles, many of these vehicles likely do not have key safety features, such as electronic stability control, which would be especially beneficial for teenage drivers. Many teenagers were driving older model year vehicles or vehicle types or sizes that are not ideal for novice drivers.Practical applicationsParents, and their teenage drivers, may benefit from consumer information about optimal vehicle choices for teenagers.     

Reasons for Child Passenger Nonrestraint in Motor Vehicles

Objective: Although child passenger restraint use in motor vehicles has increased, there is an important minority of children who remain unrestrained. The goal of this study was to identify the frequency of and under what circumstances parents keep their children unrestrained.

Methods: A cross-sectional, online survey was distributed to parents and caregivers of children 10 years old and younger. Survey participants were asked about child restraint practices, including frequency of and reasons for nonuse of restraints. Parents were specifically asked how acceptable it would be to keep their child unrestrained in certain situations.

Results: One thousand two hundred eighty-five parents and guardians responded to the survey and 1,002 completed it; 23.8% (95% confidence interval [CI], 21.3–26.6%) of respondents said they had driven with their child not fully restrained on at least one occasion. Approximately 1 in 5 parents strongly or somewhat agreed that it would be acceptable to keep their child unrestrained in certain situations, including a short drive, in a rush, an inadequate number of restraints, riding in a taxi, if somebody was holding the child, and as a reward for a child. Parents were more likely to agree that it was acceptable to keep their child unrestrained under nearly all circumstances listed if they were male, ages 18–29, with a graduate school education, in the $100,000+ income bracket, or Latino.

Conclusions: There are certain situations for which parents find it acceptable to leave their children unrestrained. This has implications for targeted child passenger safety efforts designed to maximize consistent restraint use.     

Situational characteristics of fatal pedestrian accidents involving vehicles traveling at low speeds in Japan

Abstract

Objective: This study aimed to investigate the situational characteristics of fatal pedestrian accidents involving vehicles traveling at low speeds in Japan. We focused on vehicles with 4 or more wheels. Such characteristics included daytime or nighttime conditions, road type, vehicle behaviors preceding the accident, and vehicle impact locations.

Methods: Pedestrian fatality data on vehicle–pedestrian accidents were obtained from the Institute for Traffic Accident Research and Data Analysis of Japan (ITARDA) from 2005 to 2014. Nine vehicle classifications were considered: Trucks with gross vehicle weight (GVW) ≥7.5 tons and <7.5 tons, buses, box vans, minivans, sport utility vehicles (SUVs), sedans, light passenger cars (LPCs), and light cargo vans (LCVs). We compared the situational daytime or nighttime conditions, road type, vehicle behaviors preceding the accident, and vehicle impact locations for accident-involved vehicles traveling at low and higher speeds across all vehicle types.

Results: The results indicate that pedestrian fatalities involving vehicles traveling at low speeds occurred more often under daytime conditions across all vehicle types. At signalized intersections, the relative proportions of pedestrian fatalities were significantly higher when vehicles were traveling at low speed, except when the accidents involved box vans or SUVs. Similarly, when vehicles turned right, the relative proportions of pedestrian fatalities were significantly higher when vehicles traveling at low speed were involved across all vehicle types. In terms of the frontal right vehicle impact location, the relative proportions of pedestrian fatalities were significantly higher when trucks with GVW ≥7.5 tons or <7.5 tons, sedans, or LCVs traveling at low speed were involved.

Conclusions: The situational characteristics of fatal pedestrian accidents involving vehicles traveling at low speeds identified in this study can guide targeted development of new traffic safety regulations or technologies specific to vehicle–pedestrian interactions at low vehicle travel speeds (i.e., driver alert devices or automated emergency braking systems). Ultimately, these developments can improve pedestrian safety by reducing the frequency or severity of vehicle–pedestrian accidents for vehicles turning right at intersections and/or reducing the number of resultant pedestrian fatalities.     

The effect of a gearshift interlock on seat belt use by drivers who do not always use a belt and its acceptance among those who do

IntroductionSeat belts reduce the risk of fatal injury in a crash, yet in 2015, nearly 10,000 people killed in passenger vehicles were unrestrained. Enhanced seat belt reminders increase belt use, but a gearshift interlock that prevents the vehicle from being placed into gear unless the seat belt is used may prove more effective.MethodThirty-two people with a recent seat belt citation and who admitted to not always using a seat belt as a driver were recruited as part-time belt users and asked to evaluate two new vehicles. Sixteen drove two vehicles with an enhanced reminder for one week each, and 16 drove a vehicle with an enhanced reminder for one week and a vehicle with a gearshift interlock the following week. Sixteen full-time belt users who reported always using a seat belt drove a vehicle with a gearshift interlock for one week to evaluate acceptance.ResultsRelative to the enhanced reminder, the gearshift interlock significantly increased the likelihood that a part-time belt user used a belt during travel time in a trip by 21%, and increased the rate of belt use by 16%; this effect approached significance. Although every full-time belt user experienced the gearshift interlock, their acceptance of the technology reported in a post-study survey was fairly positive and not significantly different from part-time belt users. Six part-time belt users circumvented the gearshift interlock by sitting on a seat belt, waiting for the system to deactivate, or unbuckling during travel.ConclusionThe gearshift interlock increased the likelihood that part-time belt users buckled up and the rate of belt use during travel relative to the enhanced reminder but could be more effective if it prevented circumvention.Practical applicationsAn estimated 718–942 lives could be saved annually if the belt use of unbuckled drivers and front passengers increased 16–21%.     

Belief about seat belt use and seat belt wearing behavior among front and rear seat passengers in the United States

Introduction: Unrestrained drivers and passengers represent almost half of all passenger vehicle occupant deaths in the United States. The current study assessed the relationship between the belief about importance of seat belt use and the behavior of always wearing a seat belt. Method: Data from 2012 ConsumerStyles were analyzed separately for front and rear passenger seating positions. Multivariable regression models were constructed to identify the association between seat belt belief and behavior (i.e., always wears seat belt) among adults. Models controlled for type of state seat belt law (primary, secondary, or none). Results: Seat belt use was higher in front passenger seats (86.1%) than in rear passenger seats (61.6%). Similarly, belief that seat belt use was very important was higher in reference to the front passenger seat (84.2%) versus the rear passenger seat (70.5%). For the front passenger seat, belief was significantly associated with seat belt use in states with both primary enforcement laws (adjPR 1.64) and secondary enforcement laws (adjPR 2.77). For the rear passenger seat, belief was also significantly associated with seat belt use, and two 2-way interactions were observed (belief by sex, belief by region). Conclusions: Despite overall high rates of seat belt use in the United States, certain groups are less likely to buckle up than others. The study findings suggest that efforts to increase seat belt use among high-risk populations, such as those who live in states with secondary or no seat belt laws and those who ride in rear seats (which include people who utilize taxis or ride-hailing vehicles) could benefit from interventions designed to strengthen beliefs related to the benefits of seat belt use. Practical applications: Future research that uses a theoretical framework to better understand the relationship between beliefs and behavior may inform interventions to improve seat belt use.     

Using naturalistic driving data to examine drivers' seatbelt use behavior: Comparison between teens and adults

ProblemTeens and young drivers are often reported as one driver group that has significantly lower seatbelt use rates than other age groups.ObjectiveThis study was designed to address the questions of whether and how seatbelt-use behavior of novice teen drivers is different from young adult drivers and other adult drivers when driving on real roads.MethodDriving data from 148 drivers who participated in two previous naturalistic driving studies were further analyzed. The combined dataset represents 313,500 miles, 37,695 valid trips, and about 9500 h of driving. Drivers did not wear their seatbelts at all during 1284 trips. Two dependent variables were calculated, whether and when drivers used seatbelts during a trip, and analyzed using logistic regression models.ResultsResults of this study found significant differences in the likelihood of seatbelt use between novice teen drivers and each of the three adult groups. Novice teen drivers who recently received their driver's licenses were the most likely to use a seatbelt, followed by older drivers, middle-aged drivers, and young drivers. Young drivers were the least likely to use a seatbelt. Older drivers were also more likely to use seatbelts than the other two adult groups. The results also showed that novice teen drivers were more likely to fasten their seatbelts at the beginning of a trip when compared to the other three adult groups.SummaryNovice teen drivers who were still in the first year after obtaining their driver's license were the most conservative seatbelt users, when compared to adult drivers.Practical applicationFindings from this study have practical application insights in both developing training programs for novice teen drivers and designing seatbelt reminder and interlock systems to promote seatbelt use in certain driver groups.     

Using interactive virtual presence to support accurate installation of child restraints: Efficacy and parental perceptions

IntroductionChild restraint systems (car seats) reduce injury risk for young children involved in motor-vehicle crashes, but parents experience significant difficulty installing child restraints correctly. Installation by certified child passenger safety (CPS) technicians yields more accurate installation, but is impractical for broad distribution. A potential solution is use of interactive virtual presence via smartphone application (app), which permits “hands on” teaching through simultaneous and remote joint exposure to 3-dimensional images.MethodIn two studies, we examined the efficacy of remote communication via interactive virtual presence to help parents install child restraints. Study 1 was conducted at existing car seat checkpoints and Study 2 at preschools/daycare centers. In both cases, existing installations were assessed by certified CPS technicians using an objective coding scheme. Participants then communicated with remotely-located certified CPS technicians via a smartphone app offering interactive virtual presence. Technicians instructed participants to install child restraints and then the installation was inspected by on-site technicians. Both before and after the remote interaction, participants completed questionnaires concerning perception of child restraints and child restraint installation, self-efficacy to install child restraints, and perceived risk of injury to children if they were in a crash.ResultsIn both studies, accuracy of child restraint installations improved following the remote interaction between participants and certified CPS technicians. Together, the two samples achieved a weighted average of 90% correct installations across a multi-point inspection. Both samples reported increased self-efficacy to install child restraints and altered perceptions about the accuracy of the child restraint installations in their vehicles.ConclusionsFindings support use of interactive virtual presence as a strategy to realize accurate installation of child restraints.Practical applicationsInteractive virtual presence between certified CPS technicians and the public via smartphone app has potential to improve proper child restraint installations broadly, including to vulnerable and underserved rural populations.     

Crash risk of ESC-fitted passenger cars

Objective: We examined both fatal and injury at-fault crashes of a population of passenger cars fitted with electronic stability control (ESC). Crash rates were calculated in relation to both registration years and mileage. Crash rates were also calculated for a non-ESC car population and crash rate ratios were calculated to compare the crash risk between ESC-fitted and non-ESC-fitted passenger cars.

Methods: Passenger car models with and without ESC were identified (ESC-equipped cars: 3,352,813 registration years; non-ESC-equipped: 5,839,946 registration years) and their vehicle information for the period 2009–2013, including mileage (ESC-equipped vehicles: 89.3 billion kilometers; non-ESC-equipped: 72.4 billion kilometers), was drawn from the national Vehicular and Driver Data Register.

The registry of Finnish road accident investigation teams was accessed and all fatal at-fault crashes among the cars in the study populations (ESC 97; non-ESC 377) for the period 2009–2013 were analyzed. The motor insurance database includes at-fault crashes leading to injuries and was utilized for analyses (ESC: N?=?8,827, non-ESC: N?=?21,437).

Crash rates and crash rate ratios were calculated to evaluate crash risk of both ESC-equipped and non-ESC-equipped passenger cars. Poisson regression was used to model crash involvement rate ratios both per registration year and per mileage for vehicles with ESC and without ESC, controlling for age and gender of the vehicle owner and vehicle mass.

Results: Passenger cars fitted with ESC showed lower crash rates than non-ESC-equipped cars in all crash types studied. In general, the difference in crash rates between ESC-equipped and non-ESC-equipped vehicles was greater when the crashes were compared to the mileage rather than registration years. The mileage-proportional crash rate of ESC-equipped cars was 64% (95% confidence interval, 61%; 67%) lower in run-off-road crashes resulting in injury and as much as 82% (65%; 91%) lower in fatal run-off-road crashes when suicides and disease attacks were not taken into account.

Conclusions: Our results show that modern passenger cars provide a significant crash risk reduction, which depends on both ESC and passive safety features introduced. Results also show that exposure evaluation in terms of registration years (or vehicle population) instead of true mileage can provide an overly pessimistic view of the crash risk.     

Raising the speed limit from 75 to 80 mph on Utah rural interstates: Effects on vehicle speeds and speed variance

IntroductionIn November 2010 and October 2013, Utah increased speed limits on sections of rural interstates from 75 to 80 mph. Effects on vehicle speeds and speed variance were examined.MethodsSpeeds were measured in May 2010 and May 2014 within the new 80 mph zones, and at a nearby spillover site and at more distant control sites where speed limits remained 75 mph. Log-linear regression models estimated percentage changes in speed variance and mean speeds for passenger vehicles and large trucks associated with the speed limit increase. Logistic regression models estimated effects on the probability of passenger vehicles exceeding 80, 85, or 90 mph and large trucks exceeding 80 mph.ResultsWithin the 80 mph zones and at the spillover location in 2014, mean passenger vehicle speeds were significantly higher (4.1% and 3.5%, respectively), as were the probabilities that passenger vehicles exceeded 80 mph (122.3% and 88.5%, respectively), than would have been expected without the speed limit increase. Probabilities that passenger vehicles exceeded 85 and 90 mph were non-significantly higher than expected within the 80 mph zones. For large trucks, the mean speed and probability of exceeding 80 mph were higher than expected within the 80 mph zones. Only the increase in mean speed was significant. Raising the speed limit was associated with non-significant increases in speed variance.ConclusionsThe study adds to the wealth of evidence that increasing speed limits leads to higher travel speeds and an increased probability of exceeding the new speed limit. Results moreover contradict the claim that increasing speed limits reduces speed variance.Practical applicationsAlthough the estimated increases in mean vehicle speeds may appear modest, prior research suggests such increases would be associated with substantial increases in fatal or injury crashes. This should be considered by lawmakers considering increasing speed limits.