Electronic tolling is a system in which a reader picks up a vehicle's tag or number plate and charges the owner's account, so the vehicle does not have to stop to pay. In India the tag is the FASTag, a sticker on the windscreen. Free-flow gantries do the same at full speed with no booth.
The FASTag holds a small chip that works by RFID, radio identification. A bank or another issuer sells the tag and links it to a prepaid account. The Ministry of Road Transport and Highways has required a tag on every vehicle since February 2021. When a car reaches a toll lane, a reader at the lane picks up the tag's number. The system finds the account linked to that tag, which is a prepaid balance, and deducts the toll. The barrier lifts. The whole process takes a second or two.
Consider a car at a toll plaza on a highway near Nashik. The reader picks up the tag, the account holds ₹800, and the toll is ₹115. The system deducts ₹115, the balance becomes ₹685, and the owner gets an SMS. The toll road operator receives the money in its own account, in a batch, through bulk payouts.
If the balance is too low, or the tag does not scan, the lane stops the car. The driver must then pay in another way, and a vehicle without a valid tag pays a higher toll. Before the tag, long queues formed at plazas, and the idling of lorries wasted fuel. For frequent private travellers, a yearly pass has been introduced that allows a fixed number of trips for one payment.
In a free-flow system, readers and cameras are on a frame above the road, called a gantry. They read the tag, or the number plate with automatic number plate recognition, at full speed. This is only starting in India, on a few highways. A tolling back office matches each passage to an account. The prepaid balance is held much like a digital wallet. The same tag can pay for parking through smart parking.
In India, many toll roads are built and run by private companies, which collect the tolls under long contracts with the government, and the systems are bought through government tenders. The scene is fare collection and tolling.