Front-to-rear crashes involving two vehicles with severe driver injury

This study investigates the risk for severe-to-fatal injury (Maximum Abbreviated Injury Scale [MAIS] 4+F) to drivers in two-vehicle crashes involving front impacts into the rear of another vehicle.

1995-2009 National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) was analyzed for driver injuries in front-to-rear crashes without rear occupants in either vehicle. The study involved 13+-year-old front outboard occupants in model year (MY) 1995+ light vehicles. Injury severity was subdivided into MAIS 0+6 and MAIS 4+F to assess the risk of severe-to-fatal injury (MAIS 4+F/MAIS 0+6). Injury risks were determined using weighted data for the drivers by impact type. Standard errors were calculated in SAS to determine ±95 percent confidence intervals. An in-depth analysis was made of individual cases with severely injured drivers in the front and rear impacts.

There were 215,163 drivers in the 15 years of NASS-CDS with known injuries in front-to-rear two-vehicle collisions; 624 were severely injured (MAIS 4+F) in the rear impacts and 124 in the front impacts. The risk for severe-to-fatal driver injury was 0.290 ± 0.241 percent in rear impacts and 0.058 ± 0.057 percent in front impacts. The difference was not statistically significant (P > .05). There were 13 unweighted cases with MAIS 4+F driver injury in rear impacts. Most (77%) involved intrusion in the vicinity of the driver's seating area with the seat supported upright or deformed forward. There were 5 unweighted cases with severely injured drivers in frontal impacts. Three (60%) involved intrusion due to offset frontal loading. There was only one crash where both drivers were severely injured.

In front-to-rear crashes with two vehicles, typically one driver was severely injured, not both. The risk of severe injury was not significantly different for drivers in the front or rear impacts. The risk was higher in rear impacts due to intrusion into the driver's seating area that supported or pushed the driver's seat forward. The risk for drivers in frontal crashes was also often related to intrusion due to offset loading and occupant compartment deformation.