Rob Fleming's letter on Monday to Pablo Rodriguez comes after a series of incidents involving commercial trucks or their cargo slamming into highway overpasses.
The Ministry of Transportation grounded Chohan Feight Forwarders' fleet in December after one of the company's trucks was involved in a sixth overpass strike in two years.
Gagan Singh says his group is "imploring" Transport Minister Rob Fleming to understand that all parties in the supply chain must be held accountable to improve road safety.