Bigger trucks bring new dangers to our roads:
higher crash rates and longer stopping distances
In its 2016 Final Report to Congress, the U.S. Department of Transportation (USDOT) found in limited state testing that heavier trucks have 47 to 400% higher crash rates (USDOT, 2016).
USDOT also found in the report that longer double-trailer trucks take 22 feet longer to stop than twin-trailer trucks on the road today.
In the report's conclusion, USDOT recommended that Congress make no changes to current truck size and weight laws and regulations.
USDOT also had previously found that multi-trailer trucks—doubles and triple-trailer trucks—"could be expected to experience an 11% higher overall fatal crash rate than single-trailer combinations" (USDOT, 2000).
Heavier trucks tend to have a higher center of gravity because the additional weight is typically stacked vertically. Raising the center of gravity increases the risk of rollovers.
Also, triple-trailer trucks are more likely to experience trailer sway and the "crack-the-whip" effect (USDOT, 2016).