In siberia, the act as oil pipelines.

railroads

rivers

trucks

highways

I'm pretty sure it's railroads, because there's not that many highways in Siberia, the rivers would be frozen over, and there's not a ton of people in Siberia. I'm sorry if I'm wrong.

railroads

Explanation:

In Siberia climate is harsh and has a long winter of minus 25 degrees celsius temperature and 70% of the oil fields are developed by the Russian and most of the roads become inaccessible in the owners thus railroads have used a means to carry the oil and the pipelines get jammed in severe winters months.