CDL Tests and Medical Documentation FAQ - Common Questions Answered
Navigating the CDL testing process and medical documentation requirements can feel overwhelming, especially for first-time applicants. This FAQ guide answers the most common questions about CDL knowledge tests, skills tests, and the medical certification process covered in Sections 1.1 and 1.2 of the CDL manual. Whether you're wondering what tests you'll need, how to prepare, or what medical requirements apply to your situation, you'll find clear answers here.
Basic Questions About CDL Tests
Q: What is a CDL knowledge test and what does it cover?
A: A CDL knowledge test is a written examination that assesses your understanding of commercial motor vehicle operation, safety procedures, and regulations. Every applicant must pass the general knowledge test, which covers vehicle inspection, basic control, speed management, space management, hazard perception, emergency procedures, and federal regulations. Depending on your vehicle class and desired endorsements, you may need additional specialized knowledge tests covering topics like air brakes, combination vehicles, hazardous materials, tank vehicles, passenger transport, school buses, or doubles/triples.
Q: What is the CDL skills test and how is it different from the knowledge test?
A: The CDL skills test is a practical, hands-on examination conducted in an actual commercial vehicle, while the knowledge test is a written exam. The skills test has three sequential segments: vehicle inspection (demonstrating you can check if a vehicle is safe to operate), basic vehicle control (maneuvering the vehicle through defined exercises like backing and parking), and on-road driving (operating the vehicle in real traffic conditions). You must pass the knowledge test before taking the skills test, and you must pass each skills segment before advancing to the next.
Q: What is the difference between a CDL endorsement and a restriction?
A: Endorsements ADD capabilities to your CDL, allowing you to operate specific vehicle types or haul specific cargo. Examples include Hazardous Materials (H), Tank Vehicles (N), Passenger (P), School Bus (S), and Doubles/Triples (T). Restrictions LIMIT what you can operate based on the vehicle used during your skills test. For example, testing in an automatic transmission vehicle results in an "E" restriction prohibiting manual transmission operation, and testing without air brakes results in an "L" restriction prohibiting air brake operation.
Q: What are the three CDL vehicle classes?
A: Class A covers combination vehicles with a Gross Combination Weight Rating (GCWR) of 26,001 or more pounds when the towed vehicle exceeds 10,000 pounds GVWR—typically tractor-trailers. Class B covers single vehicles with a GVWR of 26,001 or more pounds, or such vehicles towing a unit not exceeding 10,000 pounds—typically straight trucks and large buses. Class C covers vehicles designed to transport 16 or more passengers (including the driver) or vehicles hauling placarded hazardous materials, when the vehicle doesn't meet Class A or B weight requirements.
Q: How many questions are on the CDL general knowledge test?
A: The exact number varies by state, but CDL general knowledge tests typically contain 50 questions covering topics from Section 2 of the CDL manual. Most states require a passing score of 80%, meaning you need to answer at least 40 questions correctly. Specialized endorsement tests have fewer questions (usually 20-30) but also require 80% to pass. Check with your specific SDLA for exact question counts and passing requirements in your state.
How-To Questions
Q: How do I apply for a CDL?
A: To apply for a CDL, first determine which class and endorsements you need based on the vehicles you'll operate. Study the appropriate sections of your state's CDL manual. Visit your State Driver Licensing Agency (SDLA) with required documents including proof of identity, Social Security card, proof of residency, and medical certification if required. Complete the application, pay fees, pass the required knowledge tests to obtain your Commercial Learner's Permit (CLP), practice driving with a qualified CDL holder, then schedule and pass the skills test.
Q: How do I prepare for the CDL knowledge tests?
A: Start by thoroughly reading all sections of the CDL manual that apply to your class and endorsements. Focus on understanding concepts rather than memorizing answers. Pay special attention to numerical values like stopping distances, following distances, and weight limits—these are frequently tested. Take practice tests from multiple sources to identify weak areas. Review any missed questions until you understand why the correct answer is right. Create flashcards for regulations and procedures.
Q: How do I find a medical examiner for my DOT physical?
A: Medical examiners must be listed in the FMCSA National Registry of Certified Medical Examiners to conduct DOT physicals. Visit the FMCSA website and use their search tool to find registered examiners near you. Many occupational health clinics, urgent care centers, and some private physicians are registered. Call ahead to verify they perform DOT physicals, ask about appointment availability and fees, and confirm what documents to bring.
Q: How do I add an endorsement to my existing CDL?
A: To add an endorsement, visit your SDLA and request to take the endorsement knowledge test. For most endorsements, passing the knowledge test is sufficient. However, Passenger (P) and School Bus (S) endorsements also require a skills test in the appropriate vehicle type. The Hazardous Materials (H) endorsement requires passing both the knowledge test and a TSA background check with fingerprinting. Fees vary by state and endorsement.
Q: How do I renew my medical examiner's certificate?
A: Schedule a DOT physical examination with a National Registry-listed medical examiner before your current certificate expires. Complete the examination, which typically takes 30-60 minutes and includes vision testing, hearing testing, blood pressure check, urinalysis, and a physical examination. If you pass, you'll receive a new Medical Examiner's Certificate. Submit this certificate to your SDLA before your old one expires to maintain your "certified" medical status.
Exam-Specific Questions
Q: What should I expect during the vehicle inspection portion of the skills test?
A: During the vehicle inspection segment, the examiner will ask you to perform a comprehensive inspection of your test vehicle. You must physically walk around the vehicle, point to or touch each item you're inspecting, name the component, and explain to the examiner what you would check and why. You'll demonstrate systematic inspection of the engine compartment, cab/interior, exterior components, coupling system (for combination vehicles), and brake system. The examiner evaluates your thoroughness and understanding.
Q: What exercises are included in the basic control skills test?
A: The basic control test includes several maneuvering exercises performed within defined areas marked by cones, barriers, or traffic lanes. Common exercises include straight line backing (backing in a straight line without touching boundaries), offset backing (backing into a space requiring direction change), parallel parking (driver side or conventional), and alley docking (backing into an alley-type space). The examiner explains each exercise before you attempt it and evaluates precise vehicle positioning.
Q: What happens if I fail part of the CDL skills test?
A: If you fail a skills test segment, you cannot continue to the next segment that day. State policies vary on retesting—some require waiting periods (often 7-14 days), some limit attempts within a given period, and additional fees typically apply. You don't have to retake segments you've already passed, but check your state's specific policies as some require starting over if too much time passes. Use the waiting period to practice the skills that caused you to fail.
Q: Are calculators allowed during CDL knowledge tests?
A: Calculator policies vary by state and testing center. Some states allow basic calculators, others prohibit them entirely. However, CDL knowledge tests rarely require complex calculations. Questions involving numbers typically test your knowledge of specific values (stopping distances, following distances, weight limits) rather than mathematical computation. Contact your SDLA to confirm their calculator policy before test day.
Q: Can I use a translator or take the CDL test in a language other than English?
A: CDL knowledge tests are available in multiple languages in many states, with Spanish being most commonly offered. However, the skills test and actual CMV operation require the ability to communicate in English with law enforcement and others. Some states allow interpreters for the knowledge test with advance arrangement. Audio versions may be available for reading difficulties. Contact your SDLA to learn what accommodations are available.
Medical Documentation Questions
Q: What is the difference between interstate and intrastate commerce for medical certification?
A: Interstate commerce involves CMV operation that crosses state lines OR transports cargo/passengers whose journey begins or ends in another state or foreign country. Intrastate commerce means operating entirely within one state with no interstate cargo or passenger connections. This distinction matters because interstate non-excepted drivers must meet federal medical standards and obtain a DOT medical card, while intrastate drivers follow their state's specific medical requirements.
Q: What medical conditions can disqualify me from getting a CDL?
A: Certain conditions may prevent medical certification or require waivers/exemptions. These include insulin-treated diabetes (exemption program available), vision below minimum standards without corrective lenses, hearing impairment below minimum standards, epilepsy or seizure history, certain cardiovascular conditions, respiratory conditions affecting ability to perform duties, and conditions causing loss of consciousness. However, many conditions now have exemption programs available.
Q: What are the vision and hearing requirements for CDL medical certification?
A: Vision requirements include at least 20/40 acuity in each eye with or without correction, at least 70 degrees peripheral vision in each eye, ability to recognize traffic signal colors, and distant binocular acuity of at least 20/40. Hearing requirements include ability to perceive a forced whisper at 5 feet or better, or average hearing loss of 40dB or less in the better ear. Corrective devices (glasses, contacts, hearing aids) may help you qualify.
Q: How long is a DOT medical card valid?
A: Medical Examiner's Certificates are valid for a maximum of 24 months, but medical examiners may issue them for shorter periods based on health conditions. Conditions requiring monitoring (certain blood pressure levels, diabetes, sleep apnea) may result in certificates valid for only 12 months or less. Your certificate must remain current for you to maintain CDL privileges. Renew before expiration—there is no grace period.
Q: What happens if I fail my DOT physical?
A: Failing a DOT physical doesn't necessarily end your CDL career. First, understand why you failed—the medical examiner must explain. Some issues are correctable (high blood pressure can be managed with medication, vision can be corrected with glasses). You may qualify for exemption programs for certain conditions. You can seek a second opinion from another registered examiner. If you have a condition that truly prevents certification, you may need to pursue non-CDL employment until the condition resolves.
Troubleshooting Questions
Q: What should I do if I fail the CDL knowledge test multiple times?
A: Multiple failures indicate you need to change your study approach. Identify which topics cause the most missed questions—these are your focus areas. Re-read those CDL manual sections slowly, taking notes. Find different study materials like online practice tests, mobile apps, or study guides that explain concepts differently. Consider formal CDL training classes. Some people learn better by hearing information, so look for audio versions. Don't rush—take time to truly understand concepts.
Q: What if my medical examiner's certificate expires before I can renew it?
A: If your certificate expires, you immediately become "not-certified" and cannot legally operate a CMV. To resolve this, schedule a DOT physical as soon as possible, complete the examination, obtain your new certificate, and submit it to your SDLA immediately. Until you complete this process, you cannot drive a CMV. There is no grace period, so prevent this situation by renewing well before expiration.
Q: My employer says I need different certification than what I have. What do I do?
A: First, carefully review the interstate/intrastate and excepted/non-excepted criteria with your actual job duties in mind. Your employer understands what type of commerce their operations involve. If they're correct that you need different certification, visit your SDLA to update your self-certification category. If changing from excepted to non-excepted, you'll need to obtain medical certification. Do this promptly—operating with incorrect certification can result in serious penalties.
Q: What if I need a CDL but have a medical condition that might prevent certification?
A: Before assuming you can't get certified, research exemption programs for your condition. FMCSA offers exemptions for insulin-treated diabetes, vision standards, seizure disorders, and other conditions. Consult with a medical examiner experienced in DOT physicals who can advise on your specific situation. Gather medical records showing your condition is well-controlled. Some conditions that once disqualified drivers now have clear pathways to certification.
Q: How do I know which sections of the CDL manual to study?
A: The CDL manual includes a chart (typically in Section 1) showing exactly which sections apply to each license class and endorsement. All applicants study Section 1 (Introduction) and Section 2 (Driving Safely/General Knowledge). Class A applicants add Section 6 (Combination Vehicles). Air brake-equipped vehicles require Section 5. Each endorsement has a corresponding section. Study ONLY the sections that apply to your specific class and endorsements.
Comparison Questions
Q: What's the difference between a CLP and a CDL?
A: A Commercial Learner's Permit (CLP) is a temporary permit that allows you to practice driving a CMV under supervision after passing the knowledge tests. A Commercial Driver License (CDL) is the full license issued after passing the skills tests. CLP holders must have a CDL holder in the vehicle at all times, cannot operate vehicles carrying passengers (except authorized personnel), and cannot operate tank vehicles with cargo. The CLP is valid for up to 180 days and must be held for at least 14 days before taking the skills test.
Q: How does the CDL transfer process work when moving to another state?
A: When you establish residency in a new state, you must transfer your CDL within a state-specified period (often 30-90 days). Visit your new state's SDLA with your current CDL, proof of identity, Social Security card, proof of new state residency, and medical documentation if applicable. Complete their application, provide self-certification, and pay transfer fees. Most states don't require retesting for a straight transfer, but some may require knowledge tests for endorsements.
Q: What are the penalties for driving without a valid CDL or medical certificate?
A: Driving a CMV without a valid CDL can result in fines up to $5,000 and possible jail time. You may also be placed out-of-service. Your employer can face fines up to $5,000 for allowing an unqualified driver to operate. Operating without required medical certification carries similar penalties. Violations appear on your driving record and can affect future employment. These penalties apply whether you never had proper documentation or allowed it to expire.
Q: What's the difference between the Hazardous Materials (H), Tank Vehicle (N), and combination (X) endorsements?
A: The Hazardous Materials (H) endorsement allows you to haul hazardous materials requiring placards in any vehicle type—it requires a knowledge test plus TSA background check. The Tank Vehicle (N) endorsement allows you to haul liquids or gases in tanks with capacity over 119 gallons individual or 1,000 gallons aggregate—it requires only a knowledge test. The combination (X) endorsement indicates you've passed BOTH tests, qualifying you to haul hazardous materials in tank vehicles.
Q: How is the CDL different from a regular driver's license?
A: A CDL requires additional knowledge and skills testing beyond standard license requirements. CDL holders are subject to stricter regulations including lower blood alcohol limits (.04% vs .08%), mandatory drug and alcohol testing, required medical certification for most drivers, and more severe penalties for violations. CDL violations in your personal vehicle affect your CDL privileges. CDL holders must report violations within specified timeframes. The CDL system exists because commercial vehicles pose greater public safety risks.
Summary
Understanding CDL tests and medical documentation requirements is your first step toward a commercial driving career. Key takeaways include:
- All CDL applicants must pass the general knowledge test, with additional tests based on vehicle class and endorsements
- The skills test has three sequential segments: vehicle inspection, basic control, and on-road driving
- Medical self-certification determines your documentation requirements based on commerce type
- Most interstate commercial drivers need a current DOT medical card
- When uncertain about requirements, contact your SDLA or choose the option requiring more documentation
Ready to test your knowledge? Start practicing with our CDL General Knowledge questions to prepare for your knowledge tests.
See our Complete Guide to CDL Tests and Medical Documentation for comprehensive information, or check our Quick Reference Cheat Sheet for key facts at a glance.