N.H. Rev. Stat. Ann. § 246:22

Whenever, after hearing upon petition or upon its own motion, the department of transportation shall be of the opinion that the public safety requires the closing of any public or private crossing over a railroad, at grade or above or below such railroad, it shall order the same to be closed or shall make such order as in its opinion the public good may require, and it shall thereafter be the duty of the parties affected to comply therewith.