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5 Chapter 1 Introduction and Background Between 1995 and 2000, over 2,000,000 people were injured during single vehicle crashes involving roadside structures. More than 280,000 sustained serious injuries. Single vehicle crashes involving roadside objects accounted for over 1/4 of all serious and fatal injuries that occurred on the roadways. The societal costs associated with these impacts consistently exceeded $70 billion annually during this time period. The function of roadside safety features, as stated by NCHRP Report 350, is: to provide a forgiving roadway and roadside for an errant motorist. The safety goal is met when the feature either contains and redirects the vehicle away from a hazardous area, decelerates the vehicle to a stop over a relatively short distance, readily breaks away or fractures or yields, allows a controlled penetration, or is traversable, without causing serious injuries to the vehicle's occupants or to other motorists, pedestrians, or work zone personnel. [38] As these devices contain, redirect or decelerate vehicles in a safe manner, the risk of impact with non- crashworthy objects at the roadside is reduced. In many cases, the roadside hardware safety systems were designed and installed over 20 years ago. These systems are based on attributes of a now outdated vehicle fleet. The current crash testing criteria utilizes more modern impacting vehicles but only two vehicle classes are required for testing. These two classes, specified in Report 350, are the small passenger car class (820 kg) and the large pickup truck class (2000 kg). These platforms adequately represent the extremes of the passenger vehicle fleet, but it remains unclear if intermediate vehicle platforms exhibit the same impact behavior as these tested vehicles. Changes in vehicle attributes over the past two decades; including size, mass and geometry; have been drastic while design criteria for roadside hardware systems have evolved at a lower rate. Those safety systems designed to perform adequately with older vehicles cannot be expected to perform similarly with more modern vehicle structures. In addition, the populations of today's vehicle classes are drastically different than those of only 5 years ago due to the increased popularity of light trucks and sport utility vehicles. These vehicles have gained popularity recently, and their market share will continue to grow based on recent projections. Due to higher CG, larger mass and varied structural geometry, this vehicle class will not interact with roadside structures like passenger cars. Conversely, small cars have decreased in popularity and their vehicle structures have become larger in recent years. As a consequence,
6 current test procedures using the 820 kg body structure may not adequately represent the current and future vehicle fleet. This study investigates these changes in vehicle attributes and the vehicle's compatibility with roadside hardware devices. A summary of this investigation is included in the next three sections of this report. First, in Chapter 2, real world crash data and case studies from the NASS/CDS and FARS databases are examined. Next, Chapter 3, the vehicle characteristics and registrations are presented to identify changes in the vehicle fleet over the past ten years. Following this, strategies to improve vehicle to roadside hardware compatibility are included in Chapter 4. In chapter 5, conclusions and suggestions for future research are given for the benefit of subsequent work in this area.
