Commercial Driver License Written Examinations

PURPOSE: This rule establishes the criteria for taking the written examination for a Class A, Class B, or Class C license. (1) The following shall be the types of written examinations for Class A, Class B, and Class C licenses: (A) Basic Knowledge Test—this examination shall consist of fifty (50) questions which shall include, but not be limited to, questions concerning safe vehicle operation, commercial motor vehicle safety control systems, procedures for safe vehicle control, principles and procedures for the proper handling of cargo, and knowledge of what constitutes hazardous material; (B) Air Brakes Test—this examination shall consist of twentyfive (25) questions which shall include, but not be limited to, questions concerning air brake systems nomenclature, dangers of contaminated air supply, implications of severed or disconnected air lines, implications of low air pressure, procedures for safe and accurate pre-trip inspections, and procedures for conducting en route and post-trip inspections of air brake systems; (C) Combination Vehicle Test—this examination shall consist of twenty (20) questions, which shall include, but not be limited to, questions concerning coupling and uncoupling procedures and procedures for performing vehicle safety inspections on combination vehicles; (D) Hazardous Material Test—this examination shall consist of thirty (30) questions which shall include, but not be limited to, questions concerning hazardous materials regulations, the hazardous materials table, shipping paper requirements, marking, labeling, placarding requirements, hazardous materials packaging, reporting hazardous materials accidents, tunnels and railroad crossings, forbidden materials and packaging, loading and unloading, cargo segregation, parking, routes, cargo tanks, emergency equipment operations, and emergency response procedures; (E) Tank Vehicle Test—this examination shall consist of twenty (20) questions which shall include, but not be limited to, questions concerning causes, prevention, and effects of cargo surge, proper braking procedures, difference in handling baffled versus non-baffled vehicles, effects of road grade and curvature on tank vehicles, and proper use of emergency systems; (F) Passenger Vehicle Test—this examination shall consist of twenty (20) questions which shall include, but not be limited to, questions concerning loading and unloading procedures, proper use of emergency exits, proper responses to emergency situations, proper procedures at railroad crossings and drawbridges, and proper braking procedures; (G) Double/Triple Trailer Test—this examination shall consist of twenty (20) questions which shall include, but not be limited to, questions concerning procedures for assembly and hookup of units, proper placement of heaviest trailer, handling and stability characteristics of double/triple combinations, and potential traffic problems of double/triple combinations; and (H) School Bus Test—this examination shall consist of twenty (20) questions which shall include, but not be limited to, questions concerning loading and unloading of passengers, emergency exits procedures for safely evacuating passengers, and state and federal laws and regulations related to safely traversing highway rail grade crossings. (2) In order to obtain a Class A license, an applicant must take and successfully complete the Basic Knowledge Test, the Combination Vehicle Test and the Air Brakes Test, if appropriate. The holder of an out-of-state commercial driver license or commercial driver instruction permit can surrender their valid out-of-state license or permit and qualify for a waiver of the Class A Written Tests. (3) In order to obtain a Class B license, an applicant must take and successfully complete the Basic Knowledge Test and the Air Brakes Test, if appropriate. The holder of an out-of-state commercial driver license or commercial driver instruction permit can surrender their valid out-of-state license or permit and qualify for a waiver of the Class B Written Tests. (4) In order to obtain a Class C license, an applicant must take and successfully complete the Basic Knowledge Test, and either the Passenger Test, the Hazardous Materials Test, or both. The holder of an out-of-state commercial driver license or commercial driver instruction permit can surrender their valid out-of-state license or permit and qualify for a waiver of the Class C Written Tests. (5) In order to obtain an H endorsement, the applicant must take and successfully complete the Hazardous Materials Test. In order to retain an H endorsement, upon renewal or transfer, the holder must take and successfully complete the Hazardous Materials Test. In addition to the required written test, all H endorsement applicants must have an approved security threat assessment to obtain or retain the endorsement, pursuant to requirements of the USA Patriot Act. (6) In order to obtain an N endorsement, the applicant must take and successfully complete the Tank Vehicle Test. (7) In order to obtain a P endorsement, the applicant must take and successfully complete the Passenger Vehicle Test. (8) In order to obtain a T endorsement, the applicant must take and successfully complete the Double/Triple Trailer Test. (9) In order to obtain an S endorsement, the applicant must take and successfully complete the School Bus Written Test. (10) An applicant who has taken and successfully completed both the Tank Vehicle Test and the Hazardous Materials Test shall be entitled to obtain an X endorsement. (11) Successful completion of a test requires a score of at least eighty percent (80%) on each test taken. (12) If an applicant does not successfully complete any written examination required in this rule, they immediately may retake the examination; however, the examiner administering the examination shall have the discretion to require the applicant to return for a retake at a later date. (13) Written examinations shall be available at all Missouri State Highway Patrol examination stations. (14) The Missouri State Highway Patrol, in conjunction with the director of revenue, at their discretion, may administer the written examinations required in this rule to selected groups at locations other than Missouri State Highway Patrol examination stations. (15) Any person who practices or attempts to practice any fraud or deception while taking any test required in this rule, or who takes the test for another, or who in any way falsifies any information in a test required in this rule shall not be licensed to operate a commercial motor vehicle or non-commercial motor vehicle for a period of one (1) year after the director discovers the falsification. AUTHORITY: sections 302.233, 302.273, and 302.765, RSMo 2016, and sections 302.010, 302.272, 302.700, and 302.735, RSMo Supp. 2025.* Original rule filed March 5, 1990, effective June 11, 1990. Emergency amendment filed June 20, 1990, effective June 30, 1990, expired Oct. 27, 1990. Amended: Filed June 20, 1990, effective Dec. 31, 1990. Emergency amendment filed Oct. 26, 1990, effective Nov. 5, 1990, expired March 4, 1991. Amended: Filed April 8, 1991, effective Aug. 30, 1991. Emergency amendment filed July 15, 1991, effective July 25, 1991, expired Nov. 21, 1991. Amended: Filed July 15, 1991, effective Oct. 31, 1991. Amended: Filed Dec. 15, 1997, effective June 30, 1998. Amended: Filed Sept. 27, 2001, effective March 30, 2002. Amended: Filed Aug. 31, 2005, effective Feb. 28, 2006. Amended: Filed Aug. 18, 2025, effective Feb. 28, 2026. *Original authority: 302.010, RSMo 1939, amended 1949, 1951, 1955, 1961, 1978, 1980, 1983, 1984, 1986, 1987, 1988, 1989, 1991, 1995, 1996, 2002, 2007, 2008, 2012, 2015, 2021, 2022; 302.233, RSMo 2004; 302.272, RSMo 1986, amended 1987, 1989, 1996, 2004, 2005, 2018, 2025; 302.273, RSMo 2004; 302.700, RSMo 1989, amended 1991, 1995, 2003, 2004, 2009, 2012, 2013, 2014, 2018; 302.735, RSMo 1989, amended 1999, 2001, 2004, 2005, 2008, 2009, 2013, 2025; and 302.765, RSMo 1989, amended 1993, 1995.