Maharashtra Traffic Police — Regarding speed limit board on the express highway

My car was driven at 73km/h
And the fine states a speed limit of 70km/h.
I want to see the board on which it is written the above speed limit. As far as i know the speed limit for light vehicles on the highway is between 80-100kmph.
This is utter nonsense for a fine of 2000₹ at the speed of 73.