ID CDL General Knowledge cheat sheet

A CDL applicant must be licensed in and obtain the CDL from their home State of domicile; a CDL from one State is valid nationwide, but a driver may hold only one driver license at a time.

The one-State license rule: holding more than one license (any State or country) is a violation; a driver must surrender the out-of-State license before a new CDL is issued.

Change of domicile to a new State requires applying for a CDL in the new home State within the State-set deadline (commonly 30 days) and surrendering the old CDL.

Minimum age: 18 for intrastate (within-State) commerce; 21 to drive a CMV in interstate commerce or to haul hazardous materials.

Core knowledge test plus a skills test (pre-trip inspection, basic control, on-road driving) are required for a CDL; the skills test must use a vehicle of the class applied for.

Classes: Class A = combination vehicles with GCWR 26,001+ lb and towed unit over 10,000 lb; Class B = single vehicle 26,001+ lb or towing 10,000 lb or less; Class C = vehicles designed for 16+ passengers or placarded hazmat below Class A/B thresholds.

A CLP (Commercial Learner's Permit) requires passing the general knowledge test plus any endorsement knowledge tests; the holder must be accompanied by a qualified CDL holder in the front seat and cannot haul hazmat or passengers.

Disqualifying medical/vision standards: 20/40 corrected vision in each eye, hearing a forced whisper at 5 feet, and a current DOT medical examiner's certificate for interstate driving.

Self-certification: drivers certify driving type (non-excepted interstate, excepted interstate, intrastate) and provide medical certification where required; failure to keep it current invalidates the CDL privilege.

T - Double/Triple Trailers: knowledge test required; no skills test; not valid for triple trailers in States that prohibit them (many States limit to doubles).

N - Tank Vehicles: knowledge test required for vehicles designed to carry bulk liquid or gaseous materials; a tank vehicle with 1,001+ gallons of hazmat also needs the H endorsement.

H - Hazardous Materials: knowledge test plus a TSA Security Threat Assessment (fingerprint-based background check) before issuance; requires 21 years of age and is not available on a CLP for hazmat cargo.

X - Tank Vehicle + Hazardous Materials combined endorsement: requires both the N and H knowledge tests and the TSA clearance; replaces carrying N and H separately.

P - Passenger: knowledge test plus a skills test in a passenger vehicle; required for vehicles designed to carry 16 or more people including the driver.

S - School Bus: knowledge and skills tests in a school bus plus the P endorsement; requires background checks and State-specific training.

Combination rules: a Class A or B CDL is required for a placarded tank vehicle over 26,001 lb; endorsement codes are printed on the license and lapse if the underlying tests are not passed.

Endorsement knowledge tests are taken at the same time as the general knowledge test for a CLP, but the H endorsement requires TSA clearance before it is added to the license.

CDL holders are held to a higher standard: a violation in a personal vehicle can disqualify the CDL, because the disqualification applies to the person, not just the CMV.

Serious traffic violations include excessive speeding (15+ mph over the limit), reckless driving, improper or erratic lane changes, following too closely, and a traffic offense in connection with a fatal accident.

Two serious traffic violations within 3 years = 60-day CDL disqualification; three or more within 3 years = 120-day disqualification.

DUI/DWI (any vehicle), refusal to submit to alcohol testing, leaving the scene of an accident, and using a CMV in a felony = 1-year disqualification for a first offense; lifetime for a second.

Driving a CMV with a BAC of 0.04% or higher is a violation even if below the 0.08% non-commercial limit; 24-hour out-of-service applies to alcohol violations.

Railroad-highway grade crossing violations (failing to stop, insufficient clearance, or failing to negotiate) count as serious traffic violations with the same 60/120-day escalation.

Driving while a CDL is suspended or revoked, or causing a fatality through negligent operation of a CMV, results in a 1-year disqualification (3 years if hazmat was involved).

A driver must notify the employer within 30 days of a conviction for any traffic violation (except parking) and notify the State of a name or address change within 30 days.

The employer must be notified within 24 hours of a conviction for a CDL holder's alcohol, drug, or refusal violation; the driver cannot drive a CMV until cleared.

Pre-trip inspection: check engine compartment (fluids, belts, hoses), lights and reflectors, tires and wheels, brakes and air lines, coupling devices, and emergency equipment before every trip.

Air brake knowledge test is required to remove the air brake restriction; the skills test must include an air brake vehicle if the restriction is to be lifted.

Basic control skills test includes straight-line backing, offset backing, alley docking, and parallel parking (or a State equivalent); the test is scored on encroachments and pull-ups.

On-road driving test evaluates turns, lane changes, intersections, railroad crossings, curves, and expressway entry/exit; automatic failure for an accident, dangerous action, or violation.

Physical ability: 20/40 corrected vision in each eye, ability to distinguish red, green, and amber, hearing a forced whisper at 5 feet, and no current clinical diagnosis of epilepsy (or State waiver).

DOT medical examiner's certificate: valid for up to 24 months; drivers with certain conditions (insulin-treated diabetes, vision or hearing exemptions) need a Federal exemption or SPE certificate.

Cargo securement: aggregate working load limit of tiedowns must be at least 50% of the cargo weight; the front of the cargo must be secured against forward movement.

Vehicle inspection and maintenance: brakes, tires, lights, and coupling devices must be inspected regularly; drivers must report defects in writing and the carrier must repair them before the vehicle is used.

Following distance: at least one second per 10 feet of vehicle length at speeds below 40 mph; add one second above 40 mph (e.g., 60-foot vehicle at 55 mph = 7 seconds).

Speed management: reduce speed by one-third on wet roads and by one-half on packed snow; on ice, reduce to a crawl and avoid sudden braking or steering.

Space management: maintain a cushion of at least one car length per 10 mph in front; keep a lane to the side open where possible and avoid driving beside other vehicles.

Hazard perception: scan 12-15 seconds ahead, check mirrors every 5-8 seconds, and use the four-second following rule in ideal conditions.

Braking: stopping distance = perception distance + reaction distance + brake lag distance + braking distance; brake lag adds about 32 feet at 55 mph for air brakes.

Night driving: headlights must be on from sunset to sunrise and when visibility is under 500 feet; dim high beams within 500 feet of oncoming traffic and 200 feet when following.

Skid control: steer in the direction of the skid, avoid hard braking, and release the accelerator; for a drive-wheel skid, ease off the accelerator and steer straight.

Railroad crossings: stop within 15 to 50 feet of the nearest rail, look and listen, and do not shift gears while crossing; never stop on the tracks.

Hazardous materials: placards are required for 1,001 lb or more aggregate gross weight of a hazard class, and for any amount of certain materials (e.g., Division 1.1 explosives, 2.3 poison gas).

Hazmat shipping papers: must be within reach while driving, kept in a pouch on the driver's door or on the driver's seat, and include the proper shipping name, hazard class, and UN number.

Hazmat parking: never park within 5 feet of a roadway, and keep 300 feet from bridges, tunnels, and railroad tracks when placarded; attend the vehicle at all times.

Hazmat incident reporting: call the National Response Center at 1-800-424-8802 for a spill, leak, fire, or explosion; notify the carrier immediately.

Tank vehicles: beware of surge and liquid movement; reduce speed on curves and stops, and be aware that a partially filled tank has more surge than a full one.

Passenger endorsement: bus drivers must announce stops, secure passengers, and load/unload only at designated stops; school bus drivers must check for children before leaving the bus.

Emergency equipment: a CMV must carry a fire extinguisher (10 BC or larger), spare fuses, and warning devices (three reflective triangles or six fusees).

Post-trip inspection: the driver must complete a written post-trip inspection report each day and report defects that affect safety; the carrier must certify repairs before the next trip.

Hours of service: 11-hour driving limit and 14-hour on-duty window after 10 consecutive hours off duty; 30-minute break required after 8 cumulative hours of driving.

60/70-hour rule: 60 hours on duty in 7 consecutive days or 70 hours in 8 days; reset with 34 consecutive hours off duty.

Sleeper berth: split into two periods, one of at least 7 hours and the other at least 2 hours, both off duty; the 14-hour window excludes the qualifying periods.

Electronic logging device (ELD): required for most interstate CMVs; paper logs are allowed only for short-term ELD malfunctions or pre-2000 engines.

Driver vehicle inspection report (DVIR): required each day for passenger-carrying CMVs and for property-carrying CMVs when a defect is found; the carrier must certify repairs.

Accident procedures: stop, protect the scene with warning devices, render aid if trained, exchange information, and report to the carrier and to the State within the required time.

Fire safety: use a fire extinguisher on a small fire only from upwind and at the base of the flame; for a cargo or fuel fire, evacuate and call for help.

Cargo inspection: check cargo securement within the first 50 miles and every 150 miles or 3 hours thereafter; recheck after any change in load or road conditions.

Air brake test: with the engine off and the system charged, apply the brakes and hold for 1 minute; leakage must not exceed 3 psi for a single vehicle or 4 psi for a combination.

Low-air warning: the warning buzzer/light must activate before pressure drops below 60 psi; the spring brakes must apply by 45 psi.

Tire inspection: minimum tread depth is 4/32 inch for front tires and 2/32 inch for all other tires; check for cuts, bulges, and proper inflation.

Brake adjustment: pushrod travel limits are set by the manufacturer; the slack adjuster must be checked and the brakes adjusted when the limit is exceeded.

Coupling: after coupling, check the fifth-wheel jaws are locked, the kingpin is engaged, and the safety latch is closed; tug test with the trailer brakes set.

Cargo securement: tiedowns must be attached to the vehicle frame or rated anchor points, not to the cargo itself; use edge protectors to prevent strap damage.

Backing: use a spotter when available; if not, get out and check the area, back slowly, and use mirrors; a driver may not back on a highway or shoulder.

Distracted driving: texting and handheld phone use are prohibited for CMV drivers; a violation is a serious traffic offense and can disqualify the CDL.

Vehicle inspection: the seven-step inspection includes the engine compartment, front axle, driver's door, fuel area, rear axle, coupling, and lights; perform it before each trip.

Emergency warning devices: place reflective triangles within 10 minutes of stopping; 10 feet behind and 100 feet ahead and behind on a two-lane road, or 200 feet on a divided highway.

Mountain driving: downshift before descending, use the same gear down as up, and use engine braking; do not ride the brakes, which can cause fade.

Hot weather: check tire pressure when tires are cold, watch for recapping separation, and carry extra coolant; reduce speed to avoid overheating.

Winter driving: use chains where required, clear snow and ice from lights and windows, and test brakes gently after driving through water.

Cargo distribution: keep the center of gravity low and centered; the front axle must carry enough weight for steering control, and the rear axle must not be overloaded.

Rollover prevention: the top-heavy load and high center of gravity make sharp turns dangerous; slow down before curves and avoid sudden steering.

Hazmat loading: never load explosives near a heat source or with incompatible materials; check the segregation table and secure the load against movement.

Vehicle weight: the bridge formula limits weight per axle group; gross vehicle weight must not exceed the manufacturer's GVWR or the State's posted limits.

Cargo securement: aggregate working load limit of tiedowns must be at least 50% of the cargo weight; the front of the cargo must be secured against forward movement.

Hazmat placards: placards must be displayed on all four sides of the vehicle for the hazard class; the placard must match the shipping paper.

Emergency response: use the Emergency Response Guidebook (ERG) to identify the material and initial isolation distances; call 911 and the National Response Center.

Driver qualification file: includes the application, motor vehicle record, road test certificate, medical certificate, and annual review; kept by the carrier for the duration of employment plus 3 years.

Annual inspection: every CMV must be inspected at least once every 12 months by a qualified inspector; the inspection report must be kept for 14 months.

Drug and alcohol testing: pre-employment, random, post-accident, reasonable suspicion, return-to-duty, and follow-up testing are required; a positive test removes the driver from safety-sensitive duty.

Clearinghouse: employers must query the FMCSA Drug and Alcohol Clearinghouse before hiring and annually; drivers must report violations and complete the return-to-duty process.

Following distance: at least one second per 10 feet of vehicle length at speeds below 40 mph; add one second above 40 mph (e.g., 60-foot vehicle at 55 mph = 7 seconds).

Speed management: reduce speed by one-third on wet roads and by one-half on packed snow; on ice, reduce to a crawl and avoid sudden braking or steering.

Space management: maintain a cushion of at least one car length per 10 mph in front; keep a lane to the side open where possible and avoid driving beside other vehicles.

Hazard perception: scan 12-15 seconds ahead, check mirrors every 5-8 seconds, and use the four-second following rule in ideal conditions.

Braking: stopping distance = perception distance + reaction distance + brake lag distance + braking distance; brake lag adds about 32 feet at 55 mph for air brakes.

Night driving: headlights must be on from sunset to sunrise and when visibility is under 500 feet; dim high beams within 500 feet of oncoming traffic and 200 feet when following.

Skid control: steer in the direction of the skid, avoid hard braking, and release the accelerator; for a drive-wheel skid, ease off the accelerator and steer straight.

Railroad crossings: stop within 15 to 50 feet of the nearest rail, look and listen, and do not shift gears while crossing; never stop on the tracks.