I think that will ultimately fall to individual tank car owners as to what they see as the most effective and efficient way to deal with the higher levels of safety required under the new DOT-111 standards. I'm not a tank car expert so I'm not about to get into the granularity of whether it's better to retrofit or to replace, but I would suspect that replacement is probably going to be a much more significant strategy than retrofit.
On April 10th, 2014. See this statement in context.