Wikipedia
e-TAG is a free-flow tolling electronic toll collection system used on all tollways throughout Australia. The system was originally developed by Transurban for use on their CityLink tollway in the late 1990s, with the system since adopted by all toll roads, bridges and tunnels in Australia. The technology has different names depending on the issuer - such as Breeze ( Eastlink Melbourne), go via (Queensland), E-toll ( Roads & Traffic Authority (NSW)) and E-way (Sydney motorways M5 and M1), however these are all interchangeable across Australia and no surcharges apply for use on other operators' toll roads.
Toll roads in Australia use free-flow tolling, with no toll booths along the entire length of the system to impede traffic flow. Australia was one of the first countries in the world to have complete, surcharge-free interoperability between rival tolling providers across different state roadway systems. In July 2007, both e-TAG and e-pass video tolling arrangements were introduced in the Sydney Harbour Tunnel, Westlink M7, Cross City Tunnel and the Lane Cove Tunnel. This measure substantially eased traffic jams heading towards electronic gantries, providing increased convenience and time savings. In early 2009, the Sydney Harbour Bridge became toll-booth free, requiring e-TAGs to be used.
There are over 850,000 e-TAG account customers, and over 1 million e-TAGs have been issued.