How much is the flip fee at BNSF?

Could you please clarify the context behind the "flip fee" you're referring to at BNSF? Typically, in the world of finance and cryptocurrency, we don't encounter this specific term in relation to BNSF, which is a major freight railroad company. Is this perhaps a fee associated with a specific service or transaction offered by BNSF, or is there a misunderstanding in terminology? Could you elaborate further on what this flip fee entails, and what it relates to specifically within BNSF's operations? This will help me provide a more accurate and informative answer.