The vehicle code for Chester County only applies to vehicles on highways and trafficways. In some of my cases as a Chester County DUI lawyer, where the person was driving and whether it was a highway or trafficway became critical to beating the case. A highway is defined as: "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 purposes of these particular travel. The term includes a roadway open to the use of the public for vehicular travel on grounds of a college or university or public or private school or public or historical Park". This can be found in Commonwealth v. Brown from 1993.
A trafficway is defined as: "the entire width between property lines or other boundary lines of every way or place of which any part is open to the public for purpose of the hickey alert travel as a matter of right or custom." See Commonwealth v. Predmore from 1985 for more details.
Of the two definitions, only that of "trafficway" has generated any appellate opinions under the DUI law, and those opinions are not necessarily clear as to what is sufficiently open to the public to constitute a trafficway.
In one case, the court held that a dirt track through a field was a Trafficway because the field was open to the public and occasionally used by the public for vehicular traffic. In another case, the court concluded that a private drive into a trailer park was not a trafficway when the testimony described the drive is a private road with only one entrance and exit through which access and egress could be obtained, and the road was a dead-end. The court did not view such a Rotas customarily open to the public for the purposes of vehicle or traffic. A condominium parking lot, not open to the public, is not a trafficway or a highway. But, a parking lot used by the public is a trafficway. When it is not clear that a particular parking lot is open to the public, the Commonwealth must establish that it is. Finally, a parking garage constitutes a trafficway, as does an alleyway leading to a government building.