U.S. railroad customer groups have demanded regulators block or put onerous conditions on the proposed merger of Union Pacific and Norfolk Southern , the Financial Times reported on Sunday.

The Union Pacific and Norfolk Southern corporations announced Tuesday the companies will merge to create America's first transcontinental freight railroad.

Big mergers sometimes lead to big layoffs. Might that happen in the Harrisburg area — home to a giant Norfolk Southern hub — if Union Pacific completes its buyout of Norfolk Southern? Probably not, according to one industry expert.