• September 27th, 2003

The Federal Motor Carrier Safety Administration (FMCSA) has given high priority to research regarding collisions between large trucks (gross vehicle weight > 4,540 kilograms (10,000 pounds)) and other vehicles on the roadway. This research aims to improve knowledge about the high-risk behaviors of truck and passenger vehicle (car) drivers.

In 1998, large trucks accounted for 7 percent of the total vehicle miles traveled but were involved in 13 percent of all traffic fatalities (5,374 of 41,471). In these truck crashes, the car’s occupants were much more likely than the truck driver to be killed (78 percent of the fatalities were car occupants) or injured (76 percent of the injuries were sustained by car occupants).(1) Two-thirds of all police-reported truck crashes involved a truck and another vehicle, and 60 percent of all truck crashes involving a fatality were two-vehicle car-truck crashes. (2)

To address this critical issue, FMCSA has set a goal to reduce truck-involved fatal crashes by 41 percent by 2008. Meeting this goal will require improving truck safety and enhancing truck and car drivers’ behavior and performance.

Conclusions And Recommendations
The findings of the fault and UDA analyses differ somewhat from earlier findings. Although part of this difference could be because data from only one State (North Carolina) were used in two of these analyses (because no national database provided the necessary variables), it is more likely that the primary differences are a result of the different databases used (fatal crashes vs. total crashes and expert opinion vs. crash analyses).

Unlike earlier fatality-based analyses in which the car driver was found to be primarily at fault, (indicating a need to target car drivers for interventions), these findings clearly indicate a need to target truck driver actions, as well (e.g., rear-end crashes).

It is difficult to identify individual UDAs that account for a significant proportion of car-truck crashes, and the UDAs identified and ranked by experts do not agree very well with crash-based analysis, at least for the subset of UDAs where NASS-GES data could be used. This suggests that if such UDA-based findings are to be used to develop new treatments or target existing treatments, improved methods to identify UDAs for both car and truck drivers are needed.

It is possible to identify critical combinations of roadway type, roadway location, and crash type that produce the most total harm. This allows researchers to combine crash frequency and severity in the same analysis, and identify important roadway types, locations, and crash types. This type of analysis could be expanded to include additional factors such as pre-crash maneuvers, driver characteristics, and others to target existing treatments better or identify specific areas where new treatments need to be developed.

The results of this effort indicate high-impact areas for future countermeasure research related to car-truck collisions. Driver, vehicle, or roadway treatment programs for truck drivers should address backing, rear-end, right- and left-turn, and sideswipe collisions, because truck drivers are more likely to be at fault in such crashes. Similar treatment programs for car drivers should focus on head-on and angle collisions. More research is needed into the driver- and roadway-related causes for these critical crash types.

Unfortunately, there is no strong consensus between the current crash-based findings and the earlier expert rankings of the most important UDAs, although both sources agree that crashes involving vehicles that do not stop at a sign/signal and crashes involving unsafe speed are important targets. More crash-based validation of expert opinions is needed; this will require defining additional critical UDAs (e.g., “inattention”) in a crash database. Finally, based on the harm analysis, there is a need to explore driver, vehicle, or roadway programs aimed at rural undivided roads and, in particular, to intersection and segment angle and merging crashes and head-on crashes. Interstate/freeway treatments aimed at reducing car-truck crashes should concentrate on elements that affect lane-change/merging crashes and rear-end crashes.