No inferences can be made of this variable since it reflects the subsets being compared. However, it does show the involved vehicle type mix. These are very important variables in determining the mix of trucks, hazardous cargo, attachments and oversized loads. Clearly contributing defects are much more a factor with trucks than they are with cars. This analysis demonstrates the breakdown of the specific defects.
Construction zones seem to be a magnet for truck crashes.
Although the total number of crashes is small, this could be a fruitful area for enforcement, especially since construction zones need non-truck enforcement as well. Upgrades and downgrades are clearly the problem areas for trucks. This further confirms the over-representation of truck crashes on major highways. The other factors listed tend to further confirm the results listed above with regard to time, location and severity.