1.8.2 Rail

1.8.2 Rail

Traditionally, crude oil was shipped by pipeline in North America. However, the growing production of shale oil from the Bakken fields in North Dakota and Montana, coupled with the slow construction of new oil pipelines, has greatly increased shipment by rail. Crude oil is commonly shipped in unit trains of 70 or more cars, which constitute a virtual pipeline [Stancil, 2012; Stancil, 2014]. In the United States, freight railroads carried 23,786,000 barrels of crude oil in 2010, rising to a peak of 382,033,000 barrels in 2014 and then decreasing to 174,539,000 barrels in 2016 [EIA, 2017c].

Canadian exports of crude oil by rail were 16,963,521 barrels in 2012, rising to a peak of 58,772,622 barrels in 2014, and then falling to 32,162,711 barrels in 2016 [NEB, 2017b].

Crude oil is transported in DOT-111 tank cars (non-pressure, insulated, or non-insulated, without an expansion dome)2 (see Figure 7).

2 Class DOT-111 tank cars made of carbon or alloy (stainless) steel are required to have a minimum shell thickness of 7/16 inch, and those made of aluminum alloy are required to have a minimum shell thickness of 1/2 inch (60 psig tank test pressure) or 5/8 inch (100 psig tank test pressure). Regardless of the material of construction, DOT-111 tank car tanks with a 60 psig tank test pressure are required to have a minimum burst pressure of 240 psig, and those with a 100 psig tank test pressure are required to have minimum burst pressure of 500 psig. DOT-111 carbon and alloy steel tanks and welded attachments must be post-weld heat treated as a unit. Tank car made of aluminum alloy are not allowed to be post-weld heat treated. DOT-111 non-pressure tank cars that haul crude oil require a lining with acid-resistant rubber or other approved rubber compound vulcanized or bonded directly to the metal tank. Detailed specifications are given in the U.S. Code of Federal

Regulations (CFR) [CFR, 2014].