1. The commission shall:

(1) Have supervision of highways and bridges which are constructed, improved and maintained in whole or in part by the aid of state moneys, and of highways constructed in whole or in part by the aid of moneys appropriated by the United States government, so far as such supervision is consistent with the acts of Congress relating thereto;

(2) Prescribe rules and regulations not inconsistent with law, fixing the duties of all persons employed by the state highways and transportation commission;

(3) Provide for aiding county highway engineers or other officials of civil subdivisions in establishing gradients and alignments, and preparing suitable systems for maintenance of highways and bridges;

(4) Cause standard plans, specifications and estimates to be prepared for the repair and improvement of highways and the construction and repair of bridges by civil subdivisions;

(5) Investigate and determine upon the various methods of road and bridge construction adapted to different sections of the state and as to the best methods of construction and maintenance of highways and bridges;

(6) Compile statistics relating to public highways throughout the state and collect such information in regard thereto as it shall deem expedient;

(7) Aid at all times in promoting highway improvement throughout the state;

(8) Prepare plans, specifications and estimates for all state highways;

(9) Let all contracts for the construction or improvement of state highways;

(10) Prescribe a system of auditing and accounting for all road and bridge moneys for the use of all highway officials, which system shall be as nearly uniform as practicable;

(11) Have power to construct, under its own direction and supervision, all roads, culverts or bridges, or any part thereof as herein provided.

2. No rule or portion of a rule promulgated under the authority of this chapter shall become effective unless it has been promulgated pursuant to the provisions of section 536.024.