New Delhi, Oct. 28 -- India is moving towards barrier-free highway tolling, combining electronic tags, number-plate recognition and, eventually, satellite-based technology. The goal is to improve traffic flow, reduce revenue leakage and potentially charge motorists according to the distance travelled. But the transition also raises questions about enforcement, privacy and billing.

Mint explains how the system could change highway travel.

Conventional toll plazas require vehicles to slow down or stop, even when payments are made electronically through FASTag. Queues can persist because of vehicle bunching, tag-reading failures, lane restrictions and peak-hour congestion.

FASTag uses radio-frequency identification (RFID) to reduce depend...