For the purposes of this article, the following words and phrases shall have the meanings respectively ascribed to them by this section:
The Commissioner of Public Works or, in the Commissioner's absence, a duly designated and acting representative.
That portion of a street or highway improved, designed or ordinarily used for vehicular travel.
The entire width between the boundary lines of every way publicly maintained when any part thereof is open to the use of the public for the purposes of vehicular travel.