Whenever the department or any county or township enters into a contract for the construction and improvement of any road or culvert, or bridge thereon, it, as a condition of such contract, shall provide therein that the contractor shall place warning signs and devices which are in conformity with chapter 39-13. When a highway is so marked, the traveler shall proceed only with great care and diligence, but nothing contained in this section makes any township, county, or the state liable for the failure of any contractor to erect such warning signs.
N.D.C.C. § 24-03-09