Mo. Rev. Stat. § 429.550
Whenever any contractor for the construction of any part of a railroad which is in process of construction, or any contractor for the repairing of any part of a railroad, shall be indebted to any subcontractor or laborer, or other person, who shall do or perform any work or labor upon or furnish any materials for said road, such subcontractor or laborer, or other person, may give notice of such indebtedness to said company in the manner herein provided; and said company shall thereupon become liable to pay such subcontractor or laborer, or other person, the amount so due, and action may be maintained against said railroad therefor; such notice shall be given by said subcontractor, laborer or other person, within twenty days after the performance of the labor or work, or the delivery of the materials, for which the claim is made; such notice shall be in writing, and shall state the amount and number of days' labor or work, and the amount, description and quantity of materials furnished and the time when the said labor or work was performed, and the time when the said materials were furnished, for which the claim is made, and the name of the contractor from whom due, and shall be signed by such subcontractor, laborer or other person, or their attorney, and shall be served on an engineer, agent or other person employed by said company having charge of the section of the road on which said labor or work was performed, or such material furnished, personally, or by leaving said notice in the office or usual place of business of such engineer, agent or person having charge, with some person over fifteen years of age; but no action shall be maintained against any company under the provisions of this section unless the same be commenced within ninety days after notice is given to the company by such subcontractor or laborer, as above provided.
§ 429.550, RSMo