In addition to the radar detail aforementioned by RLW, they are also there to observe inspection and motor vehicle equipment violations, seat belt usage, open container and drug paraphenalia, DWI and even toll evaders!
Yep, even with fully uniformed NHSP officers standing by, some fools still attempt to evade the tolls (I observed such an individual attempt same Thursday afternoon about noon in the northbound stiles at the Hookset Tolls).
It is amazing what some people do in (or to) their cars in plain sight.
