The pipeline supports a national ambition to export oil out of North America, but faces NEB hearings and challenges from leaders in British Columbia.

Pipeline company Kinder Morgan has firmed up its relationship with two of the contractors lined up for the expansion of the Trans Mountain line in Canada.

Macro Spiecapag Joint Venture has been contracted for the Spread 5B (Coquihalla-Hope) portion of the Project, while Kiewit Ledcor TMEP Partnership will provide engineering, procurement and construction for the Lower Mainland/Spread 7 section. The Lower Mainland scope includes Spread 7, Burnaby Mountain tunnel and three terminals: Westridge Marine Terminal, Burnaby Terminal and Sumas Terminal.

The company said those represent formal arrangements with two of the six companies that agreed to take part under a September memorandum of understanding. "The remaining four are expected to be signed in the near future," Kinder Morgan said in a statement.

Canada's National Energy Board (NEB) approved Kinder Morgan's plans to triple the capacity of the network to around 890,000 barrels of oil per day last November, though vetting is still under way for some aspects. The project is part of a national effort to tap into markets outside North America.

Western Canadian leaders, however, have expressed concerns about Trans Mountain's expansion and the increase in tanker traffic. In early August, British Columbian Environment and Climate Change Strategy Minister George Heyman and Attorney General David Eby said they secured legal counsel to challenge Kinder Morgan's project.

On the pipeline itself, Kinder Morgan said the existing 715-mile network has been in service for nearly 65 years with few safety problems. Its supplies eventually make up about 90 percent of the gasoline in many markets in British Columbia.

Meanwhile, the NEB announced on Wednesday that detailed route hearings for Segment 7 will begin in January 2018 in Burnaby, BC. Hearings will follow detailed route hearings in segments one and two in Alberta this fall. Hearings in relation to the remaining four segments will be announced at a later date.

The 1,147 km pipeline project was approved by the Government of Canada in November 2016 along an approximate 150 metre wide pipeline corridor.