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E-TAG
E-TAG
E-TAG
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e-TAG toll gantries on the Tullamarine Freeway section of Melbourne's CityLink

e-TAG is a free-flow tolling electronic toll collection system used on all tollways throughout Australia. It 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 had different names depending on the issuer, such as Linkt (Transurban, includes former names E-way and go via), Breeze (ConnectEast for EastLink),[1] and E-toll (Transport for NSW for Sydney Harbour Bridge and Tunnel).[2] However, these are all interchangeable across Australia and no surcharges apply for use on other operators' toll roads.[3]

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.[4] 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 one million e-TAGs have been issued.[as of?][5]

Technology

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The e-TAG electronic tolling is based on radio-frequency identification (RFID) transponders using the DSRC protocol. The system uses electronic transponders provided by Kapsch (called e-TAGs) mounted on the inside of the vehicles' windscreen. Gantries constructed over each carriageway record registration plates and detect the e-TAGs. As the vehicle continues along the toll road, additional gantries monitor the distance travelled. Associated software then determines the toll amount payable, which is automatically deducted from the prepaid account associated with the tag. Where a tag is not detected, the vehicle's registration is recorded using video tolling technology which incorporates an automatic number plate recognition system and checked against a government motor registration database.

For infrequent use of the system a user can buy a Daypass – by phone, online, at any Australia Post outlet or at participating service stations. A Daypass can be bought in advance or afterwards (until midnight three days later).[6]

If payment has not been made after three days, the vehicle's registered owner will be sent a late toll invoice in the mail, and if the late toll invoice is then not paid a fine will be issued. In Victoria fines are issued by Civic Compliance Victoria.

The life of the battery in an e-TAG transponder is approximately five years. Customers are advised when a device is about to expire and to contact the issuer should their e-TAG not beep as they pass a tolling gantry, to receive a replacement device.[7]

See also

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References

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Official site

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E-TAG

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from Grokipedia
The e-TAG, or electronic Tag, is a standardized electronic messaging system used in the North American wholesale electricity markets to initiate, approve, and track interchange transactions, which are agreements to transfer electrical energy between balancing authority areas. It specifies critical details such as the source and sink balancing authorities, transaction energy profiles in megawatts, transmission service reservations, and priority levels for curtailment during reliability events. Developed and overseen by the North American Electric Reliability Corporation (NERC), the e-TAG facilitates coordinated power flows across the interconnected grid, ensuring operational reliability and compliance with reliability standards. Implemented on September 22, 1999, by NERC, the e-TAG replaced inefficient manual processes like fax, email, and telephone communications for scheduling energy transfers, significantly improving speed, accuracy, and transparency in transaction processing. Its primary purpose is to support grid reliability by enabling reliability coordinators and balancing authorities to assess the impacts of proposed transactions on transmission constraints, implement curtailments if needed under NERC policies, and maintain real-time visibility into scheduled interchanges. The system operates through a network of service authorities, including agent services for tag creation and dissemination, approval workflows involving multiple stakeholders, and integration with tools like the Interchange Distribution Calculator for equitable cost allocation. Over time, e-TAG standards have evolved through collaboration between NERC and the Wholesale Electric Quadrant of the North American Energy Standards Board (NAESB), with versions such as 1.7 incorporating enhancements for dynamic scheduling, error handling, and multi-region support to accommodate growing market complexity and renewable integration. Today, it plays a vital role in market monitoring by providing near-real-time data to detect anomalies, prevent transmission congestion, and ensure just and reasonable rates as mandated by the Federal Energy Regulatory Commission (FERC).

Overview

Definition and Purpose

The e-TAG (electronic Tag), also known as an Interchange Transaction Tag, is a standardized electronic messaging system used in the North American wholesale electricity markets to initiate, approve, and track interchange transactions—agreements to transfer electrical energy between balancing authority areas. It contains critical details of an interchange transaction required for its physical implementation, including the source and sink balancing authorities, transaction energy profiles in megawatts (MW), transmission service reservations, and priority levels for curtailment during reliability events. The primary purpose of the e-TAG is to facilitate coordinated power flows across the interconnected grid, ensuring operational reliability and compliance with reliability standards set by the North American Electric Reliability Corporation (NERC). It enables reliability coordinators and balancing authorities to assess the impacts of proposed transactions on transmission constraints, implement curtailments if needed under NERC policies, and maintain real-time visibility into scheduled interchanges. The system supports market monitoring by providing near-real-time data to detect anomalies, prevent transmission congestion, and ensure just and reasonable rates as mandated by the Federal Energy Regulatory Commission (FERC).

History and Development

The e-TAG system was first implemented by NERC on September 22, 1999, to replace inefficient manual processes such as fax, email, and telephone communications for scheduling energy transfers. This marked a significant improvement in speed, accuracy, and transparency for transaction processing in wholesale energy markets. In 2002, oversight expanded to the North American Energy Standards Board (NAESB), standardizing e-TAG across regions and integrating it with NERC reliability standards. The system has evolved through collaborative efforts between NERC and NAESB's Wholesale Electric Quadrant, with key versions including 1.8.1 (adopted October 27, 2009) and 1.8.4 (approved February 18, 2020). As of 2023, e-TAG continues to operate under NAESB WEQ Version 004 Business Practice Standards and NERC's Interchange Scheduling and Coordination (INT) Reliability Standards, supporting real-time scheduling and compliance.

System Components

Types of e-Tags

The e-TAG system supports various types of electronic tags corresponding to different interchange transaction characteristics and operational needs in the wholesale electricity markets. These types are defined in the NAESB Electronic Tagging Functional Specifications and NERC standards to ensure proper scheduling, reliability assessment, and curtailment handling. Normal e-Tags are used for standard energy interchange transactions, specifying fixed energy profiles in megawatts over time, source and sink balancing authorities, and associated transmission service reservations. They form the basis for routine power transfers and are subject to standard approval and curtailment priorities. Dynamic e-Tags accommodate variable energy flows, such as those from renewable resources or dynamic scheduling arrangements, where the energy profile is estimated initially and updated in near real-time based on actual generation or load. These tags require coordination with balancing authorities and reliability coordinators for ongoing adjustments. Emergency e-Tags are issued for urgent reliability situations, such as generation or transmission outages, allowing post-facto submission and higher priority to support system restoration. They are limited to specific conditions and must comply with NERC emergency operations standards. Other specialized types include Capacity e-Tags for importing operating reserves, which define reserve levels without initial energy flow until dispatched, and Recallable e-Tags for supplemental services like regulation that may be interrupted. Additionally, e-Tags are categorized by curtailment priority levels (1 through 7), ranging from highest (e.g., firm transmission) to lowest (e.g., non-firm monthly), determining order during transmission loading relief events.

Issuance and Management Process

The issuance of e-Tags is initiated by purchasing-selling entities (PSEs) through accredited agent services, which create and submit the electronic tag via the NERC-approved e-TAG system. The process requires a confirmed transmission service reservation on the Open Access Same-Time Information System (OASIS) and includes details such as points of receipt/delivery, energy profiles, market interfaces, and curtailment priorities. Submissions must adhere to NERC/NAESB timing requirements, typically at least 20 minutes before the operating interval. Once submitted, the e-Tag undergoes a multi-party approval workflow involving source and sink balancing authorities, transmission providers, and reliability coordinators. Each entity validates the tag for technical feasibility, transmission availability, and reliability impacts, responding with approvals, denials, or requests for adjustments within specified timelines. Approved e-Tags are disseminated to all relevant parties, including the Interchange Distribution Calculator (IDC) for flow impact analysis and congestion management. Management involves real-time monitoring and updates through the agent service, allowing for profile adjustments due to changes in generation, load, or market conditions, provided they comply with NERC variance policies. The system tracks tag status (e.g., active, approved, curtailed) and integrates with reliability tools for curtailment under Transmission Loading Relief (TLR) procedures. Reliability coordinators maintain oversight, ensuring compliance and providing data for audits and anomaly detection. As of 2020, enhancements in versions like 1.9 support multi-region transactions and improved error handling.

Implementation

Participant Requirements

To participate in the e-TAG system, market participants such as purchasing-selling entities (PSEs), balancing authorities (BAs), and transmission providers must register with the North American Energy Standards Board (NAESB) and comply with North American Electric Reliability Corporation (NERC) reliability standards, including Policy 3 on transmission loading relief. Participants are required to designate authorized agents or service providers for e-Tag creation and submission, ensuring adherence to NAESB Electronic Tagging Functional Specifications (e.g., Version 1.8.1 as of 2009, with subsequent updates). This registration provides secure credentials for accessing the system, enabling only compliant entities to initiate interchange transactions across balancing authority areas. The implementation process involves full-time monitoring of e-Tags by control areas, transmission providers, and PSEs to assess impacts on reliability and transmission constraints. Training and familiarization with e-TAG procedures are facilitated through NERC and NAESB resources, including standards documentation and coordination with regional entities like reliability coordinators. Compliance is enforced through NERC audits, with violations potentially leading to penalties under federal reliability standards. Participants must maintain records of submitted e-Tags, including transaction details such as energy profiles, source/sink areas, and curtailment priorities, for at least the retention period specified in NERC standards (typically several years for audit purposes). Tags must be submitted electronically in advance of the transaction schedule, with real-time updates for modifications or curtailments during reliability events.

Technical Integration

The e-TAG system operates as a secure, web-based network managed by NERC in coordination with third-party service authorities, such as those provided by vendors like OATI, facilitating electronic submission and approval workflows across North America. It uses standardized protocols defined in NAESB specifications for data exchange, ensuring encrypted transmission and compatibility with energy management systems (EMS) in balancing authorities and reliability coordinators. Technical requirements include reliable high-speed internet access and support for current web browsers to handle real-time interactions during operational hours. The system integrates with the Interchange Distribution Calculator (IDC) for calculating parallel flows and equitable curtailment distribution under transmission loading relief (TLR) procedures. e-Tags are formatted with specific elements, including unique e-Tag IDs, transaction types (e.g., energy, dynamic schedules), market and physical segments, and transmission reservations, often using XML-based structures for automated processing. Security features encompass user authentication via secure logins, session management, and validation of transaction data against NERC databases to prevent invalid schedules. Audit logs capture all submissions, approvals, and modifications for compliance and market monitoring by the Federal Energy Regulatory Commission (FERC). Integration with regional transmission organization (RTO) and independent system operator (ISO) platforms, such as those in NYISO or CAISO, allows for seamless synchronization of schedules and real-time visibility into interchanges, supporting grid reliability as of the system's evolution through 2025.

Impact and Transition

Benefits and Adoption

The e-TAG system has significantly enhanced the efficiency and reliability of interchange transactions in North American wholesale electricity markets by replacing manual processes with standardized electronic messaging. Implemented in 1999, it enables rapid initiation, approval, and tracking of energy transfers, reducing processing times and errors associated with fax, email, or phone communications. This has improved operational transparency, allowing reliability coordinators and balancing authorities to better assess transmission impacts and implement curtailments as needed under NERC standards. A major benefit is its contribution to market monitoring and regulatory compliance. By providing near-real-time data on transactions, e-TAG supports the detection of anomalies, prevention of transmission congestion, and assurance of just and reasonable rates, as required by the Federal Energy Regulatory Commission (FERC). The system facilitates equitable cost allocation through integration with tools like the Interchange Distribution Calculator and has been instrumental in maintaining grid stability amid increasing market complexity, including renewable energy integration. Adoption has been near-universal across the interconnected North American grid, with all balancing authorities and transmission service providers required to use e-TAG for scheduling since its inception, encompassing thousands of daily transactions as of 2025. For stakeholders, e-TAG offers targeted advantages: market participants gain faster transaction approvals and reduced administrative burdens; reliability entities achieve better visibility into scheduled flows for risk management; and regulators benefit from enhanced data access for oversight and policy development. These impacts have solidified e-TAG's role as a foundational tool for coordinated power flows, supporting the evolution of deregulated energy markets.

Evolution and Standards Updates

The e-TAG standards have continuously evolved through collaborative efforts between NERC and the North American Energy Standards Board (NAESB), with periodic updates to the Electronic Tagging Functional Specification addressing emerging needs such as dynamic scheduling and multi-region transactions. The current version, 1.8.4, was approved in 2020 with a minor correction effective November 27, 2023, incorporating enhancements for error handling and integration with modern grid technologies. NAESB conducts annual reviews, with the 2025 evaluation confirming the specification's adequacy while identifying potential refinements for future renewable and storage integrations. This iterative process ensures e-TAG remains compatible with FERC-approved business practices and NERC reliability standards, without a wholesale transition to a new platform. As of November 2025, the system continues to operate seamlessly, with ongoing developments focused on cybersecurity enhancements and real-time data analytics to support increasing electrification demands. No major systemic overhaul is planned, but adaptations for emerging flexible resources are under consideration in NERC's reliability assessments.

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