Since the early 1980s, the category of vehicles referred to as light trucks and vans (LTVs) has grown dramatically. LTVs consist of trucks of 10,000 pounds gross vehicle weight or less; pickups, vans, minivans, truck-based station wagons, and sport utility vehicles (SUVs). Between 1980 and 1996, the number of vehicles in the U.S. fleet grew at a compound annual growth rate (CAGR) of 2 percent. LTV sales grew at a 7.8 percent (CAGR) rate and represented 34 percent of the fleet and 44 percent of new vehicle sales in 1996. During this same time period, the mix of vehicles comprising LTVs has changed, primarily due to the popularity of minivans and SUVs.
The primary drivers of growth in LTV sales have been the decline in the cost of gasoline to consumers and increasing global competition. Global competition has forced auto manufacturers to better understand consumer needs and build innovative products, such as LTVs, to satisfy those needs. The popularity of LTVs with U.S. consumers and a growing number of consumers in other countries has made U.S. automobile manufacturers the global leaders in this vehicle category. Nonetheless, the emergence of this new type of vehicle has raised a number of very complex safety issues; including the relationship between:
Light vehicles are defined as passenger cars and LTVs. Between 1980 and 1996, light vehicle-to-light vehicle fatalities were virtually unchanged: In 1980, there were about 10,596 fatalities; in 1996, 10,497. Understanding the trend in fatalities is difficult because there are factors that could drive the totals in either direction. For example, factors that should drive the trend lower include: greater use of seat belts and child safety seats, introduction of air bags, reductions in alcohol and drug impaired driving, and improvements in vehicle safety resulting from regulatory activities. Examples of forces that should drive fatalities higher include: increased vehicle miles traveled, congestion, number of aggressive drivers, fleet size, population, and demographic mix changes.
There are two characteristics of LTVs that could potentially drive fatalities higher: rollover propensity and compatibility. In fatal crashes, SUVs are twice as likely to have rolled over than passenger cars. A rollover increases the likelihood of occupant ejection, fatality or injury.
Compatibility involves differences in vehicle characteristics between passenger cars and LTVs such as weight, height off the ground, geometry and stiffness. NHTSA crash statistics demonstrate that, in side impact crashes, LTVs are more injurious as a striking vehicle than are passenger cars. For example, when LTVs strike passenger cars on the left side, the risk of death to the car driver can be 30 times higher than the risk to the LTV occupant. This compares to a driver fatality ratio of 6.6 to 1 in car-to-car left side impact crashes.
Figure 1 shows that the number of multi vehicle crash fatalities attributable to LTV-car crashes has been increasing while those attributable to car-car crashes has been decreasing. However, it is not known whether this trend is reflecting the increased numbers of LTVs, the disparity in engineering characteristics between LTVs and passenger cars, or other factors such as vehicle use and driving behaviors.
Although vehicle weight is only one characteristic distinguishing LTVs from cars, it is most often cited when discussing the issue of vehicle incompatibility. In general, when heavy vehicles strike lighter vehicles the overwhelming majority of fatalities occur in lighter vehicles. Figure 2 shows the weight distribution in new passenger vehicle sales for selected periods from 1975 to 1997.
The weight distribution in figure 2 indicates that approximately 65 percent of new vehicles sales weighed more than 4000 pounds in 1975 compared to 40 percent in 1997. Thus, the driver of a new 2000 pound vehicle in 1997 was less likely to be in a crash with a new heavier vehicle than he/she was in 1975. Figure 2 and this example do not take into consideration engineering characteristics such as structure or height off the ground. And, in the mid 1970s, disparate engineering characteristics existed between small cars like the ubiquitous Volkswagen Beetle and large American cars that predominated U.S. highways. While the incompatibility of vehicles in crash situations does not appear to be a new issue, the recent growth in LTVs as a percent of the U.S. fleet requires that continued research and development resources be invested to further understand and find solutions that ameliorate this potential problem.
To underscore the agency's concern about the issue, Administrator Ricardo Martinez plans to convene a summit on LTV safety this June. The gathering will include everyone involved in the issue _ manufacturers, suppliers, safety advocates and experts, consumer groups and government agencies. The summit is scheduled to coincide with the International Technical Conference on the Enhanced Safety of Vehicles (ESV) in Windsor, Ontario, Canada.
The overall objective of NHTSA's safety program is to make LTVs as safe as possible for occupants and for the occupants of other vehicles involved in a crash. NHTSA has two focal points in its strategy to meet this objective: (1) research and rulemaking coupled with enforcement, and (2) consumer information and driver behavior modification.
Research and rulemaking efforts focus on improving crash avoidance, crash worthiness and the compatibility of LTVs with other passenger vehicles in multi vehicle crashes. Enforcement ensures that manufacturers comply with safety standards and correct safety defects. Consumer information and driver behavior efforts provide consumers with relevant safety information to use in the vehicle purchase decision and represent an attempt to influence driver behavior in such areas as impaired driving, belt use, and aggressive driving.
Crash Testing: A series of frontal-frontal and frontal-side crash tests are to be completed by the summer of 1998. In these tests, three classes of LTVs - a SUV, minivan, and pickup - will be used to impact a mid-size passenger car. The test results will reveal insights as to the effect of mass, stiffness, and geometry in these two types of collisions.
Simulation and Systems Modeling: Because the crash tests involve only a few possible collision scenarios, a computer model is being developed to provide information about vehicle crashworthiness in a much larger number of crash scenarios. These scenarios include a range of collision partners, collision speeds, occupant height and age, and occupant injury tolerance levels. Results of the analysis for passenger cars will be available in late 1998. These data will provide the agency with a more complete understanding of the impact of the three design characteristics on vehicle crashworthiness, and the information could be used by vehicle designers to create a safer LTV or passenger car.
Almost 60 percent of fatalities in rollover crashes occur when occupants are ejected through doors or windows. In other cases, the roof crushes, causing head or neck injuries, or occupants are thrown around inside the vehicle hitting hard surfaces. In addition to efforts to increase seat belt use, the agency has many research programs underway to prevent fatalities and reduce the severity of injuries in rollovers. These programs could also achieve benefits in crashes not involving rollovers.
In 1995, the agency issued a final rule requiring upper interior head protection for the pillars, side roof rail, and front and rear headers. This will result in protection for the upper interior hard surfaces in rollovers. In 1997, the agency issued a Notice of Proposed Rulemaking (NPRM) to allow dynamic systems to provide protection to these areas.
Handling and Stability: This program focuses on single vehicle on-the-road rollovers, which comprise less than 10 percent of all rollover crashes. Recently, the agency collected test track data for different maneuvers to determine whether a vehicle response to an extreme, but realistic, steering maneuver could induce a rollover. A small number of maneuvers were found to be more likely than others to induce a rollover. Expanded testing of these maneuvers is planned for the summer, 1998, so that a decision can be made by the end of the year as to whether a rulemaking is needed.
Collision Avoidance Systems: Longer-term research is under way on roadway departure sensing and warning capability. Ideally, the vehicle could detect when it is traveling too fast for an upcoming turn and would warn the driver to slow down before the vehicle runs off the road, thus reducing the risk of a rollover.
Rollover Labels and Consumer Information: The agency is considering a change to the rollover warning label for utility vehicles to make it more effective by providing more information to consumers on size and safety, and rollover susceptibility.
Ejection: The agency has been researching new test procedures to address the 2,300 fatalities annually due to ejection through opened doors. In addition, about 7,500 people die a year from complete or partial ejection out of windows. A potential countermeasure which is being evaluated is the use of advanced side glazing for vehicles. The agency will prepare a report summarizing the results of all testing by July, 1998 and make a decision on rulemaking action by the end of the calendar year. Dynamic interior head air bag protection systems have also been shown to reduce ejections.
Roof Crush and Seating Systems: The agency is researching changes to the roof crush standard. The agency will prepare an analysis of the results of this research by May and make a decision on possible rulemaking actions by October, 1998. In addition, the agency is researching improved integrated seating systems that are strong enough to reduce the effects of roof crush and could be more effective in rollover crashes by having the shoulder belt attached closer to the occupant's shoulder.
Agency evaluations have found that vehicles with anti-lock brake systems (ABS) have a statistically significant increase in the single vehicle run-off-road crashes (rollovers or impacts with fixed objects). It is unknown to what extent, if any, this increase is due to incorrect use of the ABS system by drivers.
The agency published a number of consumer information brochures and programs on ABS such as "Stomp and Steer", and "With ABS, Don't Let Up".
International Harmonization: In the first week of February 1998, NHTSA recommended to the United Nations Group of Experts on Braking that the new U.S. Standard for LTV brakes be adopted as a worldwide standard.
Consumer Information: The agency is investigating the possibility of providing consumer information on passenger car and LTV stopping distance, on dry and wet roads, as well as ABS performance.
ABS Research: The agency is trying to determine why ABS are not as effective in reducing fatalities as anticipated. The agency is investigating driver behavior in panic braking situations on both the test track and in a driving simulator. The agency is also conducting tests on the test track of vehicles with ABS over a broad range of real world situations.
Evaluations: Statistical analyses will be performed to determine whether newer generation ABS have better real world performance.
Seat Belts: In 1996 approximately 40 percent and 50 percent of drivers of utility vehicles and pickups respectively, involved in fatal crashes did not wear their seat belts. These rates are above those for passenger cars (38 percent) and vans (29 percent). Increased seat belt usage among owners of pickups and utility vehicles could reduce fatalities and injuries.
Alcohol: Although the trend in alcohol related fatalities is down, alcohol remains a serious problem in fatal crashes involving passenger cars and LTVs. In 1996 approximately 33 percent and 27 percent of drivers of utility vehicles and pickups respectively, involved in fatal crashes had measurable levels of alcohol in their blood. These rates are above those for drivers of passenger cars (26 percent) and vans (16 percent). Reducing the use of alcohol among drivers of utility vehicles and pickups could decrease the number of fatalities and injuries.
Speeding/Aggressive Driving: In 1996, speeding was the second most frequently mentioned factor associated with fatal crashes.
Seat Belts: Current research in this area is focused on efforts to gather data on teenagers and other high risk, low usage groups to aid in developing programs to increase their belt use. Projects are underway to develop guidelines for matching safety education strategies to youth characteristics, and to develop strategies for encouraging states to upgrade from secondary to standard enforcement of belt use laws. In addition, included in the National Economic Crossroads Transportation Efficiency Act (NEXTEA) as part of the performance based incentive grants, States will have to meet seat belt usage goals; therefore, those that are currently not collecting seat belt usage information will need to begin to do so.
Alcohol: A number of research activities are underway to refine target group descriptions, the affects of alcohol on the driving behavior of specific target groups, and to reexamine the relative crash risk among drivers at various levels of alcohol concentration.
Speeding/Aggressive Driving: Current research focuses on a survey of public attitudes and behaviors toward speeding and other unsafe driving actions, a crash investigation study to examine the role of unsafe actions in crashes and a review and analysis of existing date to suggest guidelines for setting speed limits.
Seat Belts: President Clinton established a national initiative to increase seat belt use called the Presidential Initiative for Increasing Seat Belt Use Nationwide. The initiative involves (1) building public-private partnerships; 2) enacting strong state legislation; 3) embracing active, high visibility law enforcement; and finally, 4) conducting well-coordinated, effective public education. Experience indicates that when these four elements exist together, they result in increased levels of belt use.
Alcohol: The Agency will implement programs with states, communities, and national organizations using the framework Partners in Progress: An Impaired Driving Guide to Action. The agency will strengthen its partnerships and seek out new allies to help America reach the national goal. NHTSA will promote passage of effective legislation, and support prevention, education and technical assistance activities for law enforcement officials, prosecutors, judges, and the public. In addition, the Presidential Initiative on Drugs, Driving and Youth will be in progress.
Speeding/Aggressive Driving: The agency's program to reduce the consequences of speeding and aggressive driving focuses on integrating traffic enforcement into overall State and community law enforcement, work with the Federal Highway Administration (FHWA) on automated enforcement equipment (to increase police effectiveness while cutting their costs), and technical assistance as well as demonstrations of interventions to deter aggressive driving. Research will study the role of speeding and aggressive driving in crashes, examine new measures against speeding, aggressive driving and other unsafe driving acts, and collaborate with FHWA on setting speed limits and studying road design solutions to speeding and aggressive driving.
Seat Belts: The goal is to increase seat belt use by drivers of all types of passenger vehicles to 85 percent by 2000 and 90 percent by 2005.
Alcohol: The goal is to reduce the number of alcohol-related fatalities, including those pickups and utility vehicles, from approximately 17,000 in 1996 to 11,000 alcohol-related traffic fatalities by the year 2005.
Speed/Aggressive Driving: The goal is to reduce speeding and aggressive driving related fatalities 5 percent by the year 2000.
For additional information on NHTSA programs,
view the NHTSA site on the World Wide Web at
or call the Auto Safety Hotline at