Is the US Using the Issue of Truck Safety as a Trade Barrier to Mexico?

1. Is the U.S. using the issue of truck safety as a trade barrier? What proof can you offer?
I think U.S. is using the issue of truck safety as a trade barrier because the increase in Mexican trucks within the limited border zone has had an adverse affect on safety in the U.S. For example, in Texas border counties, within the commercial border zone, have seen a dramatic increase in highway fatalities and serious injuries from truck with Mexican registration. Another dramatic case in California, a Mexican truck was involved in a 10-car pileup that killed four California motorists north of San Diego. These fatal crashes are bound to increase if the border is opened, and the number of trucks increases rapidly without meaningful Mexican safety system in effect.
On the other hand, The North American Free Trade Agreement (NAFTA) was supposed to create unrestricted access to markets throughout the North American continent.
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