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View All PlansYou must pass the CDL General Knowledge Exam and the CDL Pre-Trip Inspection Test before obtaining a Commercial Driver’s License (CDL). At that point, you can then earn the T Endorsement, which allows you to legally operate double or triple trailer combinations (triples are prohibited in DC). To do this, you must pass the Doubles/Triples Knowledge Test. The District of Columbia CDL Double/Triples Trailers Exam is based on the most recent District of Columbia CDL manual (District of Columbia CDL Handbook). This official DMV exam consists of 20 multiple-choice questions, and you must correctly answer at least 16 questions (80%) to pass. If you fail, the DC DMV requires a minimum one-business-day waiting period before retesting, and additional fees may apply after multiple attempts.
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Our free District of Columbia CDL Doubles/Triples Practice Tests are different from the standard study guides you can find elsewhere online. Designed to mirror the actual exam format, you’ll benefit from real-time feedback, hints, and AI-driven learning tools. All of these work to improve retention and help you pass on your first attempt.
Questions are derived from the most recent District of Columbia CDL Manual and include safety topics specific to doubles and triples. These include coupling/uncoupling procedures, preventing rollovers and jackknifing, managing the “crack-the-whip” effect, adjusting following distances, and conducting trailer inspections.
Earning your T Endorsement is a substantial value-add to your CDL as it opens access to potentially higher-paying jobs and many more driving opportunities. The District of Columbia features many major logistics companies like FedEx Ground, Old Dominion Freight Line, and XPO Logistics. Additionally, DC’s major roadways like I‑95 and the nearby commercial hubs, such as Baltimore, Northern Virginia, and Philadelphia, increase demand for drivers with the doubles/triples certification.
Most double and triple trailer combinations use air brakes, and the Air Brakes Knowledge Test must also be passed to become eligible to drive any vehicle with air brakes. Passing the Air Brakes Knowledge Test and a skills test in a vehicle with air brakes allows for the removal of any “L” or “Z” restriction from your CDL. Additional endorsements available in DC include (N): Tank Vehicles; (H): Hazardous Materials; (X): Tank/Hazmat Combo; (P): Passenger Vehicles; and (S): School Bus. Each endorsement requires a separate knowledge test, and we have exactly what you need to prepare for these as well.
This Practice Test is one of two in our District of Columbia-specific Doubles/Triples series. But don’t stop there. Be sure to also check out our full suite of practice materials for combination vehicles, air brakes restriction removal, and all valuable endorsements!
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Our trademarked system automatically saves questions you miss, creating personalized tests that target your weak spots until you’ve mastered the material.
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We build our practice questions from the current 2025 DC Driver Handbook and refine them using patterns recent test‑takers report.
Driver handbook • Knowledge‑test/permit overview • Fees & ID requirements • Office/appointment info
We mirror recurring themes (e.g., right‑of‑way traps, sign look‑alikes) and use similar distractors and wording styles.
We don’t collect or publish actual test items and we’re not affiliated with DMV.
