Pipeline Profiles: TransCanada’s Canadian Mainline

Pipeline system and key points

Section updated June 2020

TransCanada PipeLines Limited (TCPL) owns the Canadian Mainline. The pipeline transports natural gas produced in the Western Canadian Sedimentary Basin to consumers in eastern Canada and the United States. Since the mid–2000s on the eastern portion of the Mainline some export points were reversed to become import points and bring natural gas produced in the Appalachian Basin into Canada.

The pipeline commenced operations in 1958. At the end of 2016, CER-regulated assets included 14 125 km of pipeline and various auxiliary infrastructure.

The Canadian Mainline extends from the Alberta/Saskatchewan border across Saskatchewan, Manitoba and Ontario, and through a portion of Quebec.

Key points on the Canadian Mainline include:

  • Prairies (Empress): interconnect with the NOVA Gas Transmission Ltd. (NGTL) system at the Alberta/Saskatchewan border near Empress, Alberta. Empress is the largest receipt point on the Mainline.
  • Emerson: export interconnect with the Viking Gas Transmission Pipeline at the Canada-U.S. border near Emerson, Manitoba.
  • Emerson II: export/import interconnect with the Great Lakes Gas Transmission Pipeline on the Canada-U.S. border near Emerson, Manitoba.
  • Northern Ontario Line (NOL): segment of the Mainline which begins near compressor 41 in Manitoba and extends to compressor station 116 near North Bay, Ontario.

Pipeline map

TransCanada Mainline pipeline system map

Source: CER

Text version of this map

This map provides an overview of the TransCanada Mainline pipeline system.

  • Eastern Triangle – NOL Receipts: includes receipts from the NOL segment which are measured at station 116 in North Bay, Ontario.
  • Eastern Triangle – Parkway Receipt: includes receipts from Parkway East, Parkway West and King’s North, all located in the greater Toronto area, Ontario.
  • Chippawa: import interconnect with the Empire Pipeline at the Canada-U.S. border near Niagara Falls, Ontario. Prior to 2015, Chippawa was an export point.
  • Niagara: import interconnect with the Tennessee Gas Pipeline and the National Fuel Gas Pipeline at the Canada-U.S. border near Niagara Falls, Ontario. Prior to 2012, Niagara was an export point.
  • Iroquois: export interconnect with the Iroquois Gas Transmission System at the Canada-U.S. border near Iroquois, Ontario.
  • Other US Northeast: export interconnects with three smaller U.S. pipelines at the Canada-U.S. border near Cornwall, Ontario and Napierville and Phillipsburg, Quebec. ‘Other US Northeast’ flows is an aggregate of these three export points.

TCPL has been adding pipeline facilities in the Eastern Triangle to meet market demand, relieve Mainline constraints and enable more natural gas to flow into Ontario from the U.S.

Official CER documents related to the construction, operation and maintenance of the Canadian Mainline can be found here: Canadian Mainline regulatory documents (facilities) [Folder 90715].

You can see the Canadian Mainline and all CER-regulated pipelines on the CER’s Interactive Pipeline Map. The map shows more detailed location information, the products carried by each pipeline, the operating status and more. You can also view maps on TC Energy’s website.

Throughput and capacity

Section updated quarterly (early March, mid-May, mid-August and mid-November)

Select key point:

Select units:

Key Point Map
Key Point Trends
Key Point Description

Note: The physical capacity of a pipeline is based on many factors such as the products being carried, direction of flow, pipeline pumping capacity, and maintenance work or other pressure restrictions. The actual physical capacity of the pipeline may, at times, be higher than the assumed operational capacity stated here.

Dashboard instructions
  • Click on a key point button above the chart & map to view traffic at a different location. The map shows approximate locations on the pipeline where throughputs & capacity are recorded by the pipeline operator.
  • Click and drag your mouse on the area chart to zoom into the desired date range. Click on the Reset Zoom button to reset the full date range.
  • Click on the chart legend items below the chart to remove & add sections of data as required.
  • The key point trends are calculated using quarterly average traffic at the key point. Natural gas throughput trends are displayed year over year (last full quarter of data compared to the same quarter last year). Crude oil and liquids key point trends are displayed quarter over quarter (last full quarter of data compared to the previous quarter).

Note: The five-year average is calculated for natural gas key points using the total throughput across all trade types and direction of flows. For bi-directional key points (both export and import) the throughput is displayed for both directions, instead of the five-year average.

Looking for daily data? Daily natural gas traffic datasets are available on Open Government.

Source and description

Data Source: Open Government

Description: The above dashboard displays pipeline throughput and capacity at key point(s) along the system. Where possible, the five-year average and five-year range for throughput is shown with the current year throughput to better highlight the trends. For pipeline key points with a defined location, a map is displayed next to the graph showing the approximate key point location where pipeline throughput and capacity are recorded.


Section updated June 2020

A toll is the price charged by a pipeline company for transportation and other services. Tolls allow pipeline companies to safely operate and maintain pipelines. Tolls also provide funds for companies to recover capital (the money used to build the pipeline), pay debts, and provide a return to investors. The interactive graph below shows Canadian Mainline tolls on major long-haul and short-haul paths. Long-haul paths have Empress as a receipt point, while short-haul paths have receipt points east of Saskatchewan, such as Union Parkway Belt. Tolls increased in January 2015 to cover costs of new facilities in the Eastern Triangle.

Open data can be freely used and shared by anyone for any purpose. The data for these graphs are available.

For several years, contracts on the Canadian Mainline showed two distinct trends. First, long-haul contracts (from Empress across the Prairies and NOL) declined and short-haul contracts (in the Eastern Triangle) increased. Across the lower utilized Prairies and NOL sections, shippers were switching to interruptible or short-term firm contracts rather than using full-year firm service.

From 2007 to 2011, the Canadian Mainline operated under a negotiated settlement based on a cost of service toll methodology. As average throughput declined and tolls increased, TransCanada and its shippers wo rked to find solutions. TransCanada filed a contested toll application (Application for Business and Services Restructuring Proposal and 2012 and 2013 Mainline Final Tolls (RH-003-2011)) [Folder 711778], the outcome of which resulted in much lower multi-year fixed tolls. Also in this decision, the Board gave TransCanada discretion in the pricing of interruptible transportation capacity. When the RH-003-2011 Decision was implemented in mid-2013, firm contracts from Empress increased.

TransCanada and three eastern local distribution companies (LDCs) returned to the Board at the end of 2013 with an application for a new toll regime incenting TransCanada to build new facilities in the Eastern Triangle (Application for Approval of Mainline 2015-2030 Settlement) [Folder 2397890]. The Board approved this application in December 2014, resulting in somewhat higher tolls, a return to cost of service tolls, and other features. This toll methodology was expected to be in place until 2020 with a review in 2017. On 18 December 2017 TransCanada filed an Application for 2018-2020 Mainline Tolls [Filing A88754].

In October 2017, the Board approved TransCanada’s Dawn Long-Term Fixed Price (Dawn LTFP) [Folder 3224371] service. Under the Dawn LTFP service, 23 shippers subscribed to transport 1.5 PJ/d from Empress to Dawn for a ten-year term, at a fixed price of $0.77/GJ.

In July 2017, the Board approved TransCanada’s Herbert Long-Term Fixed Price service [Folder 3173691]. Under this service, one shipper subscribed to transport 58 TJ/d from Empress to the Herbert delivery point in Saskatchewan for a 10-year term, at a fixed price of $0.12/GJ.

A list of shippers on the Canadian Mainline is available on TC Energy's website (Contract Demand Energy, Future Contract Demand Energy reports).

Official CER documents related to the traffic, tolls and tariffs for the TransCanada Mainline can be found here: TransCanada Mainline toll documents [Folder 92843].

Pricing discretion for firm and interruptible transportation

Section updated June 2019

The TransCanada Mainline offers several transportation services on its pipeline. Interruptible transportation (IT) service has lower priority than firm transportation (FT) so it may be subject to curtailment. IT is auctioned daily to the highest bidder – above bid floors set by TransCanada. Short term firm transportation (STFT), which has a minimum term of seven days and a maximum term of one year less a day, is also auctioned to the highest bidder (above a specified bid floor). Current and historical bid floor levels for IT and STFT, by path, are available on TC Energy’s website.

Biddable IT and STFT services for the TransCanada Mainline came into effect July 2013, following the NEB’s RH-003-2011 Decision. Since May 2015 TransCanada files additional monthly information for IT and STFT services in its Quarterly Surveillance Reports [Folder 155521], including posted bid floors by path, total contracted quantities, number of counterparties and total monthly revenues. This information is available in the dashboard below.

Abandonment funding

Section updated June 2020

The CER requires all pipelines to set aside funds to safely cease operation of a pipeline at the end of its useful life. In 2016, TCPL estimated it would cost $2.9 billion to do this for the Mainline. Starting in 2015 these funds are being collected over 25 years and set aside in a trust.

Table 1: Canadian Mainline’s abandonment trust fund balance
  2015 2016 2017 2018 2019
Trust fund balance ($) 162 564 000 304 719 000 466 237 000 619 297 000 816 406 000

Official CER documents related to abandonment funding can be found here, sorted by year and by company: abandonment funding documents [Folder 3300366].

Pipeline financial information

Section updated June 2020

Pipeline companies report important financial information to the CER quarterly or annually. A solid financial position enables companies to maintain their pipeline systems, attract capital to build new infrastructure, and meet the market’s evolving needs. The data in this table comes from Canadian Mainline’s Quarterly Surveillance Reports [Folder 155521].

The Mainline’s revenue increased from 2014 on due to increased contracting and the ability to set higher tolls for non-firm services.

Canadian Mainline financial information

Section updated June 2020

Table 2: Canadian Mainline financial data
  2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
Revenues (million $) 1 818 1 856 1 559 1 519 1 645 2 397 2 128 1 900 1 772 1 487
Net income (million $) 263 247 266 273 293 201 187 180 169 162
Average rate base (million $) 6 447 6 165 5 776 5 752 5 612 4 617 4 074 3 924 3 678 3 534
Return on rate base (%) 8.49 8.45 9.17 9.21 9.50 9.01 9.30 9.54 9.46 9.32
Deemed equity ratio (%) 40 40 40 40 40 40 40 40 40 40
Return on equity (%) 10.2 10 11.5 11.88 13.06 10.86 11.50 11.50 11.50 11.44
Corporate financial information

Section updated June 2020

The Canadian Mainline is owned and operated by TransCanada PipeLines Limited (TCPL). TCPL has operations in Canada, the United States and Mexico and operates three core businesses: natural gas pipelines, liquids pipelines and energy. In 2016, the Mainline accounted for approximately 10% of TCPL’s net income. TCPL’s credit ratings remain investment grade.

Credit ratings provide an idea of the financial strength of a company, including its ability to attract capital to build new infrastructure and meet financial obligations. The credit ratings below are expert opinions of how likely the debt issuer is to live up to its obligations. TransCanada also publishes recent credit ratings on its website.

Table 3: TransCanada PipeLines Limited credit ratings
  2012 2013 2014 2015 2016 2017 2018 2019 2020
DBRS credit rating A A (low) A (low) A (low) A (low) A (low) A (low) A (low) A (low)
S&P credit rating A- A- A- A- A- A- BBB+ BBB+ BBB+
Moody’s credit rating A3 A3 A3 A3 A3 A3 A3 Baa1 Baa1
Financial regulatory audits

Section updated June 2020

The CER audits pipeline companies to confirm compliance with the Canadian Energy Regulator Act, regulations, CER orders and CER decisions. Financial regulatory audits focus on toll and tariff matters such as detecting cross-subsidies. The Canadian Mainline’s last audit was completed in March 2017. Official CER documents related to the Canadian Mainline’s financial regulatory audits can be found here: [Folder 571547].

Safety and Environment

Conditions Compliance

Section updated June 2021

Every pipeline company in Canada must meet federal, provincial or territorial, and local requirements. This includes Acts, Regulations, rules, bylaws, and zoning restrictions. Pipelines are also bound by technical, safety, and environmental standards along with company rules, protocols and management systems. In addition to these requirements, the Commission may add conditions to regulatory instruments that each company must meet. Conditions are project-specific and are designed to protect public and the environment by reducing possible risks identified during the application process.

Condition compliance is part of the CER's oversight and enforcement action is taken when required.

Conditions can be related to a specific region, or apply to the pipeline project as a whole. The map below displays the number of in progress and closed conditions mapped to economic regions as defined by Statistics Canada.

Conditions can typically be either in-progress or closed. The CER follows up on in-progress conditions.


This status refers to conditions that continue to be monitored by the CER. This happens when:

  • condition filings have not yet been received by the CER; or,
  • filings have been received but are under review or do not yet meet requirements; or,
  • a project is not completed and it has conditions, which have not been met; or,
  • a project has a post-construction condition, but a requirement has not yet been completed; or,
  • some conditions may be active indefinitely or refer to the continued operation of a pipeline.

This status refers to:

  • condition requirements that have been satisfied, and no further submissions from the company are required; or
  • conditions whose filings or actions apply to a specific phase that have been fulfilled as the phase is completed (i.e. a specific filing during construction phase). Note: comments on the required actions can still be received.

Source and description

Data Source: Open Government

Description: The above map displays the number of CER conditions associated with projects approved by the Commission. The map is split into two tabs which show in-progress and closed conditions separately, mapped to an economic region. If a company has no in-progress conditions specific to an economic region, the dashboard will default to show the closed conditions by region. An additional view is available which contains the number of in-progress and closed conditions that don't have a corresponding economic region in the dataset. The map regions are shaded based on the number of conditions, with lighter colored regions containing fewer conditions compared to darker colors. Conditions that apply to more than one region are double counted in the map, and these conditions will appear in the map region total and map region breakdown for each applicable region. The condition counts contained in the map navigation buttons represent total conditions without region double counting.

Open data can be freely used and shared by anyone for any purpose. The data for these graphs are available [CSV].

Have you checked out the CER's interactive conditions data visualization? This tool offers a deep dive into the CER's conditions compliance data and process, exploring conditions across all CER regulated companies by keyword, project, and location.

Pipeline Incidents

Section updated June 2021

The information presented here is based on CER data (2008 to current) for incidents reported under the Onshore Pipeline Regulations and the Processing Plant Regulations. New data is added quarterly. Learn more on how incident data collection has evolved since the NEB (now the CER) was established in 1959.

Companies must report events, such as incidents, to the CER in accordance with the CER Event Reporting Guidelines. Knowing what happened, and why, helps us find ways to prevent them from happening again.

What is an incident? (Onshore Pipeline Regulations (OPR))

As defined in the OPR, “incident” means an occurrence that results in:

  1. the death or serious injury to a person;
  2. a significant adverse effect on the environment;
  3. an unintended fire or explosion;
  4. an unintended or uncontained release of low vapour pressure (LVP) hydrocarbons in excess of 1.5 m³
  5. an unintended or uncontrolled release of gas or high vapour pressure (HVP) hydrocarbons;
  6. the operation of a pipeline beyond its design limits as determined under CSA Z662 or CSA Z276 or any operating limits imposed by the CER.
What is an incident? (Processing Plant Regulations (PPR))

As defined in the PPR, “incident” is defined as an occurrence that results or could result in a significant adverse effect on property, the environment, or the safety of persons. For the purposes of incident reporting in the PPR, events that fall under this definition include, but are not limited to:

  1. the death or serious injury to a person;
  2. a significant adverse effect on the environment;
  3. an unintended fire or explosion that results in or has the potential to result in damage to company, public/crown or personal property;
  4. an unintended or uncontained release of low vapour pressure (LVP) hydrocarbons in excess of 1.5 m³
  5. an unintended or uncontrolled release of gas, HVP hydrocarbons, hydrogen sulfide or other poisonous gas; or
  6. the operation of a plant beyond its design limits or any limits imposed by the CER.
Incidents and the CER

Companies self-report incidents and are expected to take a precautionary approach in doing so. This means that even when there is doubt as to whether an incident should be reported, the company must report it. The approach is, “When in doubt, report.” This is consistent with CER-regulated companies’ responsibility for anticipating, preventing, mitigating and managing incidents of any size or duration.

The CER reviews all reported incidents to assess whether companies have taken the appropriate corrective actions and to identify potential trends in incidents. Each incident is given a status indicating the current stage of the CER's incident review.

CER Status
  • Initially Submitted: The company has notified the CER that an incident has occurred and provided preliminary information. A review has been initiated.
  • Submitted: The company has submitted all of the required information and the CER is reviewing the incident.
  • Closed: The CER’s incident review has been completed and the file is closed.
Incident type definitions: one incident can have multiple types
  • Release of Substance (featured in the dashboard) - Any time a product is unintentionally released. (Releases of non-gas low pressure products in volumes of less than 1.5 m³ are exempt from reporting.)
  • Adverse Environmental Effects - When any chemical substance is released at a concentration or volume that has the potential to change the ambient environment in a manner that would cause harm to human life, wildlife or vegetation (e.g., glycol, potassium carbonate, methanol, methanol mix from hydrostatic testing, etc.).
  • Explosion - An unintended explosion
  • Fatality - Any death involving employees, contractors or members of the public related to the construction, operation, maintenance or abandonment of pipelines
  • Fire - An unintended fire
  • Operation Beyond Design Limits Includes situations, such as:

    • over-pressures - i.e., pressures that are higher than the maximum the equipment was designed to safely handle;
    • vibration beyond design limits;
    • slope movements causing movement in the pipeline beyond design limits;
    • pipe exposures in rivers or streams; and
    • introduction of an inappropriate product (e.g., sour gas in excess of CSA limits)

    Operation beyond design limit is typically linked to an over-pressure of the product in the pipe; however, if a pipe was exposed to excessive vibration and was not designed for this, this could be considered operation beyond design limits. Operation beyond design limits does not include equipment contacting the pipe, or corrosion pits, etc.

  • Serious Injury (CER or Transportation Safety Board) - Any serious injury involving employees, contractors or members of the public related to the construction, operation or maintenance of pipelines.
Are there any incidents near me?
Select range (100km):
Source and description

Data Source: Open Government

Description: The above map displays the location of product release incidents that have occured on the pipeline system since 2008. The map defaults to show incidents as bubbles which are colored based on the substance released. Incidents on the map can be re-categorized based on the most recently available status of the CER's incident review, the year in which the incident was reported, and the province/territory where the incident occured. The incident map bubble can be switched to show the estimated volume of product released, with larger map bubbles showing larger release volumes relative to other product releases on the system. The incident data can also be toggled to display a stacked bar chart of incidents over time by clicking on the incident trends button above the map. The stacked bars dispaly the number of product release incidents by year, with bar color segments corresponding to the various products released. Similiar to the map, incidents can be re-categorized by clicking on the side buttons to view a breakdown of incidents by status, what happened, why it happened, and province/territory.

Open data can be freely used and shared by anyone for any purpose. The data for these graphs are available.

Have you checked out the CER's interactive incident data visualization? This tool offers a deep dive into the CER's incident data trends, exploring incidents across all CER regulated companies.

Emergency management

Section updated June 2020

The CER checks to make sure companies are keeping pipelines safe by doing inspections, in-depth safety audits, and other activities. Yet, even with these precautions, an emergency could still happen. Sound emergency management practices improve public safety and environmental protection outcomes, and provide for more effective emergency response.

The CER holds its regulated companies responsible for anticipating, preventing, mitigating, and managing incidents of any size or duration. Each company must have an emergency management program that includes detailed emergency procedures manuals to guide its response in an emergency situation. We oversee the emergency management program of a regulated company’s projects as long as they operate.

The CER requires companies to publish information on their emergency management program and their emergency procedures manuals on their websites so Canadians can access emergency management information. To view the Canadian Mainline’s Emergency Response Plans, see TransCanada’s Rocky Mountain Region, Central Region, Northern Ontario Region, and Eastern Region plans at its Emergency Preparedness website.

Date modified: