Let's say there are three cars accosted at every traffic light change, which happens every 30 seconds, and gives Rs 10 for the forced "cleaning", from 8 am to 8 pm.
The takings for one day, at one traffic light:
12 hrs x 60 mins x 2 changes of lights per minute x 3 cars x Rs 10 = 43,200. Per day.
Annual income = 43,200 x 300 days (allowing for vacations) = 12,960,000. Tax-free.
Not bad.