On the flip side, those against speed limiters say there will be a negative impact on the industry and roadway safety:
Unintended safety consequences: a difference in speed between vehicles on the highway creates more interactions between vehicles which can lead to unsafe driving conditions. On two-lane roads, especially, speed limiters could pose increased safety risks if and when vehicles of any kind can’t achieve a safe passing speed.
Increased congestion: Bottlenecks are created and congestion results when vehicles travel at different speeds over the same network. The most acute problems would occur on two-lane roads, but four-lane divided highways would be affected, too.
Increased emissions: the net reduction in emissions assumes that the flow of traffic will not be affected. If speed limiters on truck cause increased traffic congestion, or force more speed adjustments by other vehicles, emissions will increase.