Accident with a commercial vehicle on a prohibited highway...still my fault?

A few days ago, coming on the Palisades Parkway North on-ramp in Rockland County, NY, I didn't see a large van that had stopped in front of me and smashed into him...totaling my car and causing very light damage to his vehicle. It was my fault, but I learned recently that commercial vehicles are not allowed to be on the Palisades Parkway...what qualifies as a commercial vehicle? (He was a food delivery man). If his large white delivery van qualifies as such, does this change my case at all? How so? Thanks in advance for any help you can provide!