N.H. Rev. Stat. Ann. § 362:3

The term "common carrier by rail" shall include every corporation, company association, joint stock association, partnership and person, their lessees, trustees, or receivers appointed by any court, owning or operating any railroad for common carriage of passengers or freight or carrying on a public express business for compensation over the line of any railroad. It shall also include all bridges and other structures owned, leased or used.