Here is some information on single unit trucks (SUTs) crash statistics from the National Transportation Board:

” Although single-unit trucks comprise three percent of registered motor vehicles and four percent of miles traveled, they are involved in nine percent of fatalities among passenger vehicle occupants in multivehicle crashes. Crashes involving single-unit trucks and passenger vehicles pose a hazard to passenger vehicle occupants due to differences in weight, bumper height, and vehicle stiffness. . .

“Many studies of truck safety have examined fatalities as the sole outcome of interest. Tractor-trailers result in a larger proportion of fatal injuries from large truck crashes, which is one reason why some truck safety regulations have been limited to tractor-trailers and trailers. However, this study shows that there are substantial societal impacts resulting from non-fatal injuries arising from single-unit truck crashes. Emergency department visits, inpatient hospitalizations,3 and hospital costs4 that result from the crashes provide measures of the adverse effect of non-fatal injuries on the public.

“This study also shows that federal and state databases frequently misclassify single-unit trucks and thus undercount the total number of fatalities resulting from single-unit truck crashes by approximately 20 percent.”

http://www.ntsb.gov/_layouts/ntsb.recsearch/Recommendation.aspx?Rec=H-13-013