I just happened to pass through one of these toll gates on the Chennai Bangalore section, last Saturday, 29 October, 2016.
There was a board indicating 3 different categories and speeds for each of these. Thus, the speed limit for autorickshaws is 60kmph, trucks, vans and heavy vehicles 80kmph and for cars, SUVs and such private vehicles it is 100kmph.
The fine for exceeding the limit would be Rs.400/-, for the first time and Rs.1000/- for a repeating incident.
I guess there are hidden speed guns installed along the route, which will be monitoring the speed of the vehicles. But, the question is, how will they know the number of the vehicle? My guess is that they have cameras installed to capture the number plate also.
So, folks. Be warned. Drive safe!