N.H. Rev. Stat. Ann. § 246:31

If any railroad shall neglect to erect or maintain fences, as provided in RSA 246:30, the owner of adjoining land may give notice thereof to any agent of the railroad; and, if the fence is not erected or made sufficient within 20 days, such owner may build or repair it and recover of the railroad twice the expense of so doing in an action on the case.