A new crash typology is developed consisting of 37 pre-crash scenarios that depict vehicle movements and dynamic as well as the critical event occurring immediately prior to crashes. The statistics for this 37-pre-crash-scenario typology are populated using 2004-2008 General Estimates System data along with additional data from the Large Truck Crash Causation Study database. Moreover, comprehensive economic costs based on 2007 economics are used to quantify their societal cost. This new analysis focuses on pre-crash scenarios involving at least one heavy truck (gross vehicle weight rating greater than 10,000 pounds), which might be addressed with crash-imminent warning systems based on short range vehicle-to-vehicle (V2V) communications. As a result, 17 of the 37 pre-crash scenarios are statistically described in terms of their societal cost, driving environment, driver characteristics, and contributing and causal factors. These statistical descriptions are used to categorize target pre-crash scenario groups that will drive future research into priority heavy truck crash kinematics and V2V-based countermeasures to reduce the frequency and harm of crashes. Five rear-end, pre-crash scenarios accounted for the most harm at about 24 percent of the societal cost of all 17 applicable V2V pre-crash scenarios, followed by two opposite-direction pre-crash scenarios that together made up 22 percent of the total societal cost. The third most harmful pre-crash scenarios were junction crossings at 17 percent of the total comprehensive economic costs. Based on 2004-2008 GES statistics about the driving environment, most crashes occurred on a straight road, dry surface, with clear weather during daylight. A large portion of crashes associated with changing lanes/drifting in the same direction, rear-end lead vehicle moving, and rear-end lead vehicle decelerating pre-crash scenarios happened on roads whose posted speed limit was greater than or equal to 55 mph. In contrast, a large portion of running stop sign, opposite direction/maneuver, and turning at non-signalized junctions pre-crash scenarios were reported at speed limits less than or equal to 35 mph. The 2004-2008 GES statistics show that the age breakdown of heavy-truck drivers was 12 percent by younger drivers (24 or younger), 85 percent by middle-age drivers (25 to 64 years old), and 3 percent by older drivers (65 or older). In terms of gender, male and female drivers respectively comprised about 94 and 6 percent of all heavy-truck drivers, respectively. Moreover, about 31 percent of drivers of interest were cited with violations, 27 percent were distracted, 10 percent were speeding, 5 percent had obscured vision, and 1 percent were involved with alcohol or drugs. In response to the critical event of the crash, steering was attempted by 16 percent of all drivers of interest, most often in opposite-direction and rear-end lead-vehicle-accelerating pre-crash scenarios. Braking only was reported for 9 percent of drivers, primarily in running-red-light, rear-end/lead-vehicle-moving, and left-turn-across-path/opposite-direction pre-crash scenarios. Based on LTCCS data, 35 percent of heavy-truck drivers had inadequate surveillance, 33 percent were following lead vehicles too closely, 27 percent were traveling too fast, 15 percent were inattentive, 15 percent had false assumptions, 11 percent were fatigued, 11 percent attempted inadequate evasive action, and 11 percent misjudged the gap or velocity between vehicles. The results of this report feed into the crash scenario framework that will be used to identify intervention opportunities and define crash countermeasure profiles based on V2V communications for heavy trucks. The statistical and kinematical depiction of target pre-crash scenarios will enable the development of countermeasure functional requirements and minimum performance specifications as well as the estimation of potential safety benefits. (Author/publisher)
Samenvatting