No I haven't. It seems completely redundant, because all trucking is obviously done over the roads...
Maybe it just means "overland shipping," i.e. not by sea or air?
Well whaddaya know! I asked Lord Google about it, and apparently it's so common that they even have an abbreviation for it: OTR trucking!
Ref: this Acrobat Reader article My goodness -- even IanMegill2 doesn't know everything!