As used in this act:
"Commissioner" means the Commissioner of Transportation.
"Good repair" means a state of structural soundness according to accepted engineering standards as incorporated in a regulation adopted by the commissioner.
"Jurisdiction" means control and responsibility for maintenance, rehabilitation and replacement, except as may be modified under the provisions of this act.
"Railroad overhead bridge" or "bridge" means any bridge carrying a highway or private road over and across a railroad, subway, or street, traction, or electric railway, or over and across the right-of-way of such a railroad, subway, or railway.