(AP) — Norfolk Southern still isn’t interested in Canadian Pacific’s sweetened offer of roughly $31 billion to buy the railroad. Norfolk Southern’s board unanimously rejected the latest offer Wednesday because the bid remains “grossly inadequate” and unlikely to be approved by regulators. Norfolk Southern says if Canadian Pacific is serious about the offer, it should ask regulators for preliminary approval of the deal’s proposed structure. Canadian Pacific rejected that idea last week as unnecessary. Canadian Pacific spokesman Martin Cej said the railroad couldn’t immediately comment Wednesday morning. Canadian Pacific has estimated that its cash and stock offer could be worth as much as roughly $40 billion to $45 billion. But much of that is based on the projected value of stock in a new company that would own both railroads.