Transporting petroleum by trains costs $10 to $15 per barrel, compared to around $5 for pipelines, but both systems have around the same capital construction costs. Railroad networks also tend to have greater coverage than pipeline networks and can carry a greater variety of cargo. This would be particularly of interest in the 1960s/1970s, when coal was having trouble and railroads in the United States were stuck with lines that weren't generating revenue but they could not easily get rid of. Interestingly, it is also easier to gain approval for railroads and they tend to spill less petroleum than pipelines. Most of this information is from here, covering the present state of petroleum transport (it might have been different in the 1960s and 1970s). Also, keep in mind this is for petroleum transport in general, not just in the United States. For example, perhaps Alaska and/or the Middle Eastern countries could choose a railroad to help with industrialization and economic diversification, or countries with nationalized railroads and electricity could choose to take advantage of their railway investments to boost railroad traffic and/or reduce capital expenditures. Perhaps the economics of transport could be improved too by using trains designed to carry large quantities of petroleum, similar to how there are trains designed to carry large quantities of coal. Based on operating costs pipelines and other forms of transportation beat railroads, but there are advantages in using existing infrastructure. Could railroads have potentially gone on to serve a more prominent role transporting petroleum?