TMX eases pipeline constraints and increases exports to overseas markets

This article was published by the Canada Energy Regulator on Sept. 3, 2025.

The Trans Mountain Expansion Project (TMEP) came online in May 2024, nearly tripling the capacity of the Trans Mountain System to a total of 890 thousand barrels per day (Mb/d). This increased total western Canadian crude oil export pipeline capacity by 13 per cent and export capacity to tidewater in western Canada by about 700 per cent.^Footnote 1 Since TMEP’s first month of ramping up, the expanded Trans Mountain System has averaged 82 per cent utilization. More broadly, constraints have eased on all of Canada’s largest export pipelines over this period and Canadian crude oil prices have improved relative to international benchmarks.

Figure 1: Monthly throughput and available capacity on the Trans Mountain System

Utilization of the Trans Mountain System since the TMEP Began Service

The Trans Mountain System has been more than 75 per cent full every month since TMEP came online, except for the ramp up period in May 2024.^Footnote 2 From June 2024 to June 2025^Footnote 3, the Trans Mountain System averaged 82 per cent utilization, ranging from a low of 76 per cent in December 2024 to a high of 89 per cent in March 2025.

Since TMEP entered service, approximately 80 per cent of the Trans Mountain System’s capacity (707.5 Mb/d) is now reserved for committed shippers with long term take-or-pay contracts and the remainder (approximately 182.5 Mb/d) is made available on a monthly basis for uncommitted (also known as spot) shippers. From June 2024 to June 2025, committed capacity was effectively fully utilized each month, averaging 99 per cent utilization.

Compared to pre-TMEP levels, the Westridge delivery point^Footnote 4—at Trans Mountain’s marine terminal located in the Port of Vancouver—has seen the largest increase in throughputs, which is driven primarily by heavy oil exports (and some light oil exports) (Figure 1). These volumes are being exported by marine vessel to the U.S. West Coast and Asia. An average of 23 vessels per month departed from Westridge marine terminal between June 2024 and July 2025.^Footnote 5 Since the startup of TMEP, Canadian crude oil exports to countries other than the U.S. have more than tripled.^Footnote 6

Light crude oil and refined petroleum products also continue to be delivered to the Burnaby delivery point to serve Parkland’s Burnaby Refinery,^Footnote 7 Suncor’s Burrard Products Terminal, and surrounding areas. Additionally, the Sumas delivery point, which connects with the downstream Puget Sound Pipeline for deliveries of crude oil to Washington State refineries, has continued to be at capacity.

The Trans Mountain pipeline historically transported mostly light oil, but heavy oil has increased to approximately match light oil volumes since the TMEP came online.

Easing capacity constraints on export pipelines

In the months leading up to the completion of the TMEP, all major oil pipelines out of western Canada were running at or near capacity, as Canadian oil production increased to record levels. Shipper requests (or nominations) to use export pipelines significantly exceeded capacity, resulting in a large rise in apportionment on the largest western Canadian oil pipelines (Trans Mountain, Enbridge Mainline and Keystone) in late 2023 and early 2024.^Footnote 8

Since the startup of the TMEP, with Canadian oil production at new highs, there has been no apportionment on the Trans Mountain System. On the Enbridge Mainline and Keystone, apportionment has fallen significantly while their total utilization remained at or near capacity. Overall, oil export pipeline capacity from western Canada continues to be highly utilized (Figure 2). Additionally, since TMEP entered service, Canada’s crude-by-rail exports^Footnote 9 have fallen to annual-average levels not seen in over a decade.^Footnote 10

Figure 2: Crude oil volumes transported from western Canada relative to available pipeline capacity

WCS price differential narrowed after the TMEP entered service
In the months leading up to the startup of the TMEP, the price differential between Western Canadian Select (WCS) and West Texas Intermediate (WTI) had widened to an average of about US$18.70 per barrel in the period of September 2023 to April 2024.Footnote 11 After the startup of TMEP, with total pipeline capacity no longer being constrained out of western Canada, the differential narrowed to an average of US$12.00 per barrel over the period of June 2024 to July 2025.

This means western Canadian oil has been worth more than if the differential had remained wider, like it was in the period leading up to the expansion. A US$12.00 per barrel differential is more in-line with historical levels seen in periods when markets did not face constrained pipeline capacity.

Figure 3: WTI-WCS monthly average price differential

Footnotes:

1. Pre-TMEP, Trans Mountain set aside 79 Mb/d of capacity for service to its Westridge Marine Terminal (54 Mb/d for committed and 25 Mb/d for uncommitted service) (Source: CER REGDOCS, A3E7A3, C27827-1). Post-TMEP, the Westridge Marine Terminal can export up to 630 Mb/d of western Canadian crude (Source: Trans Mountain, Westridge Marine Terminal). Actual monthly throughputs may exceed the set-aside capacities.
2. In May 2024, system utilization averaged 55 per cent while Trans Mountain ramped up shipments on the new capacity.
3. This 13-month period excludes the ramp-up period during the first month of TMEP operations and includes the latest available throughput data at the time of publication (which Trans Mountain filed with the CER in August 2025).
4. See the Trans Mountain Pipeline Profile for a map of the delivery point locations.
5. Trans Mountain, Shipper Services. At the time of publication, datapoints for June 2024 and July 2024 were removed from the Trans Mountain webpage as it only shows the 12 most recent months. Prior to the update, the webpage showed vessel departures for those two months were 21 and 22, respectively. Vessel departures for August 2024 were 23.
6. See the Commodity Tracking System report for Crude Oil – Summary Export by Destination. Data includes all exports from Canada, not just from Port of Vancouver. Note that crude oil delivered to “other” destinations are primarily non-U.S. destinations but also includes some volumes that are held in storage in the U.S. before reaching a final destination as well as some volumes that are in-transit in the Pacific Area Lightering zone.
7. Burnaby Refinery is currently owned by Parkland Corporation. However, Parkland Corporation and its assets are being bought by Sunoco LP (Parkland News Release).
8. See the Trans Mountain, Enbridge Mainline and Keystone Pipeline Profiles for visualizations of monthly apportionment. To access the raw dataset, visit the Open Government Pipeline Throughput and Capacity Data.
9. See the CER’s Canadian Crude Oil Exports by Rail – Monthly Data webpage to access the data.
10. Rail is typically used when pipeline infrastructure is not available, or when price differentials are wide enough for rail to be economic. The differential that is required to justify shipping crude by rail varies by shipper. While the use of rail has declined recently, it is still integral to serving regions without pipelines.
11. WCS is typically discounted relative to WTI because WCS is a heavier crude oil that costs more to refine than WTI light oil, and because of the cost to ship WCS from western Canada to Cushing, Oklahoma, where WTI is commonly bought and sold.