DC CDL General Knowledge study guide
DC CDL General Knowledge · Work through your exam, one topic at a time.
The DC CDL General Knowledge test is the core written knowledge exam that anyone pursuing a District of Columbia commercial driver's license must pass before moving on to endorsement tests and the skills (road) test. It is designed for drivers who intend to operate Class A, Class B, or Class C commercial vehicles - tractor-trailers, straight trucks, tankers, and certain passenger or hazmat vehicles - in and around Washington, DC. The DC CDL General Knowledge study guide has 12 sections and about 4,891 words.
01Vehicle Inspection and Basic Control
The DC CDL General Knowledge exam opens with this domain: what federal rules require you to confirm before moving, how to set the seat and mirrors so you can actually see, and what to feel for in the first mile. Questions are situational - a gauge reading, a mirror image, a symptom that appears at 5 mph.
454 words, about 2 min02Shifting, Backing, and Turning
This domain tests the low-speed skills that decide most CDL skills-test failures and many real crashes: shifting without damaging the drivetrain, backing without a spotter accident, and turning a long wheelbase without clipping a curb, a car, or an overhead sign. Heavy non-synchronized transmissions need double-clutching or floating with matched RPM; do not force a gear.
449 words, about 2 min03Seeing Hazards and Space Management
The General Knowledge exam uses this domain to test whether you see problems early and keep room to solve them. Hazard perception is graded as a skill: look far ahead, scan constantly, and treat every developing situation as a hazard until it is resolved.
404 words, about 2 min04Speed Management and Stopping Distance
This domain tests whether you understand what actually determines stopping distance and how to choose a speed for conditions, not for the posted sign. Expect questions that ask you to add up perception, reaction, brake lag, and braking distance, or to pick a safe speed on a descent or in rain.
392 words, about 2 min05Skid Control and Emergencies
This domain tests recovery technique and emergency decision-making: what to do when traction is gone, when the brakes fail, or when a tire blows at highway speed. The exam favors the counterintuitive answer - usually, less braking and less steering input, not more.
392 words, about 2 min06Sharing the Road and Distracted Driving
Urban general knowledge questions in DC lean heavily on this domain: dense traffic, cyclists in marked lanes, pedestrians mid-block, and a handheld phone ban that applies to commercial drivers. The exam asks you to predict what other road users will do and to recognize that a large vehicle cannot stop or swerve like a car.
413 words, about 2 min07Fatigue, Alcohol, and Driver Wellness
This domain is about the driver rather than the truck: hours-of-service limits, the physiology of fatigue, the commercial alcohol standard, and the medical rules that keep a CDL valid. Exam questions often test the arithmetic of a 14-hour window or the assumption that coffee and fresh air undo impairment.
402 words, about 2 min08Cargo Securement and Weight Limits
This domain tests the rules that keep a load on the truck and the truck under legal weight. Expect arithmetic: aggregate working load limit, number of tiedowns, axle weights, and the federal bridge formula.
374 words, about 2 min09Hazardous Materials and Vehicle Marking
This domain covers placarding thresholds, shipping papers, parking and smoking rules, and the equipment a placarded vehicle must carry. Questions are usually threshold questions: does this load need a placard, and which one?
355 words, about 2 min10Railroad Crossings and School Buses
This domain tests the two situations where the law takes judgment away from you: you must stop at a railroad crossing when the rules say so, and you must stop for a school bus loading or unloading children. Both carry heavy penalties and both appear frequently on the DC exam.
435 words, about 2 min11Vehicle Systems and Pre-Trip Inspection
This domain tests the numbers and procedures of the inspection itself: air brake tests, pushrod travel, tire tread depth, steering play, and the coupling checks on a combination vehicle. Expect questions that ask you to compare a measurement against a limit.
408 words, about 2 min12Accident Procedures and Reporting
This domain tests what you do in the ten minutes after a crash: where the warning devices go, who you call, what you say, and what you must report afterward. Answer choices often hinge on protecting the scene and avoiding statements about fault.
413 words, about 2 min