That's an interesting question, and I wish there were a short answer. Unfortunately, I think locomotives are currently equipped with LVVR. The only cost that the railways will see is for the maintenance of that and access to it. Positive train control or cab override systems or those types of things would involve a multi-billion dollar input on the part of the railways.
First of all, let me say that I hope we're not arguing about these things. We're discussing them. I think it's the line of least resistance right now. LVVR is something that exists, and the railway companies are seeking to exploit the legislation. Whether they are interested in putting billions of dollars into positive train control and those types of things, I don't know.
Whether that's the answer or not.... I don't know if that helps you, but that's the concern I have with respect to what you have asked.