There's no such national test. You'll have to talk to each DOT individually. Most DOTs don't do a whole lot of field welding of bridges except in repair situation, but TX does a fair amount.
At least I assume you're talking about field welding. For shop welding, the fabricator you work for will handle your qualification testing.
Hg
AWS'ers
Latest contact info I have is
Louisiana Dept. of Transportation and Development
Johnny B. Bradberry, Ph.D., Secretary 1201 Capitol Access Rd.
Baton Rouge, La. 70804-9245 225-379-1201
225-379-1851 (Fax) www.dotd.state.la.us
! Lived there long enough to be an official ---!
Len