302.745.  Chemical tests, requirements — implied consent given, limits — use as evidence, test results. — 1.  All chemical tests required herein for the enforcement of sections 302.700 to 302.780 shall be conducted using the same procedures, methods, waivers of liability, persons and facilities as those described in chapter 577 except as provided in sections 302.700 to 302.780.  Nothing contained in chapter 577 shall be construed to require a person to be placed under arrest prior to his or her being requested to submit to a chemical test under this section.

  2.  A person who drives a commercial motor vehicle within this state is deemed to have given consent, subject to the provisions of this section, to a chemical test or tests of his or her breath, blood, saliva or urine for the purpose of determining his alcohol concentration, or the presence of controlled substances in his or her system.

  3.  A test or tests may be administered for the purposes of enforcing sections 302.700 to 302.780, at the direction of a law enforcement officer, who has reason to believe that the driver was driving a commercial motor vehicle while having any amount of alcohol or controlled substances in his or her system.

  4.  The implied consent to submit to the chemical tests listed in subsection 2 of this section shall be limited to not more than two such tests arising from the same arrest, stop, incident, or charge.

  5.  Upon the request of a person who is tested, full information concerning the test shall be made available to him or her.

  6.  Upon the trial of any person for violation of this section or upon the trial of any criminal action or violations of county or municipal ordinances arising out of acts alleged to have been committed by any person while driving a commercial motor vehicle under the influence of alcohol or controlled substances, the amount of alcohol or controlled substance in the person's blood at the time of the act alleged as shown by chemical analysis of the person's blood, breath, saliva or urine is admissible in evidence and the provisions of subdivision (5) of section 491.060 shall not prevent the admissibility or introduction of such evidence, if otherwise admissible.  Nothing contained in this section shall be construed as limiting the introduction of any other competent evidence bearing upon the question whether the person was operating a commercial motor vehicle while under the influence of alcohol or controlled substances.