I don't know anything about the reasons for this merger. Maybe it makes sense, maybe not. Some mergers happen just because a company is sitting on a pile of cash and the board doesn't know what to do with it. The default option is to buy another company.
My overall take is that there have been to many mergers of railroads and other companies. This destroys price and service competition. I think that regulators should take a hard look at this. Bigger is not always better. NH Joe