NYAirOne, I'm surprised that you're aren't hearing anything on 453.4250 / 453.5250. As k2hz suggests above, the pairs aren't just used by NYSP Troop T (7_ series) units and the Authority's maintenance / engineering / administrative (1_, 2_, 3_ or 4_ series, depending on the Division) units, but also by:
- franchise tow trucks (5_ series units)
- the Highway Emergency Local Patrol (HELP) trucks (6_ series units), when they are out (usually during the rush hours)
- contactors (8_ series units; albeit very rarely), and
- the Thruway's emergency service vehicles (9_ series units)
Then there are the all ambulance corps authorized on the Authority's system (e.g.: Tarrytown for the Tappan Zee Bridge, Woodbury Community for the Exit 16 interchange) that ID in the clear.
That's a lot of radios on one system. So much so that unless I'm traveling on the Thruway system itself, I end up locking out the channels. I suggest you check your gear / settings.