The problem with that language is that if I have a railway that carries traffic on the railway line of another railway, and there's an accident, who has control of the traffic is technically speaking the railway that's carrying the traffic. I think the intention of the government was to avoid debate as to what was the cause of the accident. It could be faulty trackage, which would be the host railway. In that case, the intention of the government was to make both railways that are physically involved in the accident liable, and that language would not address it.
On April 30th, 2015. See this statement in context.