That would depend on who is performing the task.
If a highway patrolman is doing it, then you might hear traffic on the Traffic channels (470.8125 / 482.4625, 123.0).
If a traffic enforcement agent is doing it, then maybe you'll hear traffic over the TED Citywide channel (471.1625, 151.4)
If a Citywide Traffic Task Force police officer is doing it, then perhaps you'll hear something over Citywide 3 (470.8625 / 482.4375, 151.4)
At one point patrol borough task force cops did truck enforcement as well, but now that the task forces are gone, I don't know if any SRGs are doing it instead.
