Under normal circumstances, a merger between railroad giants would be so outlandish that they would never consider publishing an announcement like this. Anything is possible these days, it seems.
It's smaller than Pfizer buying Warner-Lambert in 1999. It's smaller (at least inflation adjusted) than Exxon-Mobil or Citicorp-Travelers. It's a lot smaller than AOL-Time Warner in 2000. It's smaller than Dow-duPont in 2015.
Why is it outlandish? Because it involves railroads?
It'd be like privatizing the roads and then allowing the closure of the small farm roads because they're "not profitable". It'd be massively short sighted and would cause problems for decades, maybe over a century as we sort things out and get back on track. It's what we're in the middle of with railroads.
Second, railroads are more efficient at hauling stuff longer distances. They are not more efficient at local pick up and delivery, though. Letting trucks take over that part makes things more efficient, not less. Your "closure of small farm roads" analogy is therefore off base.