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Training American Truckers since 1963

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CDL Restrictions and Requirements

There are specific restrictions and requirements concerning the types of cargo that can be transported with a Commercial Driver's License (CDL), especially concerning hazardous materials and livestock:


As a commercial license holder, pursuing a career as a commercial driver, offers you a lot of employment opportunities. But at the same time, it's very important to perceive the complexities of CDL classes, endorsements, and the possible restrictions. Understanding this intricate web of CDL related information is very crucial for the legal and safe transportation of passengers or even for any kind of hazardous materials and also very helpful in mastering the road skills. 

This comprehensive article is all based on the information, for a better understanding of the specific requirements and restrictions for transporting different types of cargo with a commercial driving license (CDL).


Unraveling the CDL Classes

CDLs are classified into three basic categories, class A, class B, and class C, based on the types of vehicles you can operate and the weight ratings they are allowed to carry legally. Let's have a look at each of these three CDL classes.

1. Class A CDL

This class offers you the permission to operate combination vehicles, such as semi trucks or tractor-trailers. By taking this class, you'll have the permission to operate these vehicles having a gross vehicle weight rating (GVWR) exceeding 26,000 pounds, and the weight of the towed vehicle exceeds 10,000 pounds. Class A CDL certificate is mandatory for tractor-trailers, truck drivers and for the drivers of trailer combinations, livestock transporting vehicles, tank vehicles and flatbeds.

2. Class B CDL

Taking this class B CDL, you can legally operate single vehicles with a GVWR exceeding 26,000 pounds, and the weight of  towing vehicles with a GVWR not exceeding 10,000 pounds. This class B CDL allows you to manage some specific vehicles such a as

Straight trucks, large passenger buses, segmented buses, tractor trailers, dump trucks with small trailers and box trucks.

3. Class C CDL

The remaining vehicles that don't fall under the category of class A or B, are the part of class C CDL. This includes the vehicles having the capacity of transporting 16 or more numbers of passengers, along with drivers. It also includes those vehicles transporting the hazardous materials that require placarding. 

Each of these above-mentioned CDL classes, have a set of some basic requirements and endorsements, that also specify the duties and responsibilities of commercial driving license holders, while  dealing with different types of commercial vehicles.

CDL Endorsements

CDL endorsements are some additional endorsements or certifications that are aligned with a commercial driver's license (CDL). Depending on the type of vehicle, CDL endorsements allow its holder to manage and drive certain types of commercial vehicles that commute or transport specific types of passengers or cargo. For example spending on requirements and regulations, passenger transport (p), hazardous materials which is also known as Hazmat, tanker vehicles (T), double trailers(T) , triple trailers(T) etc., are included in CDL endorsements. These endorsements also enable the CDL drivers to expand their transportation capabilities and career opportunities.

1. Hazardous Materials Endorsement (H)

Hazardous material endorsement is also known as Hazmat endorsement (H), it gives you the permission to carry or transport hazardous materials including chemicals, flammable liquids and explosives. Due to the security and safety issues, acquiring its certifications is not an easy task because you have to undergo a strict background checks, written tests, and pass some specialized training.

2. Passenger Endorsement (P)

This type of endorsement gives the authority to the drivers of commercial vehicles such as buses or vans, to transport or carry passengers. So passenger endorsement is mandatory for safely transporting the passengers from place to place.

3. School Bus Endorsement (S)

This type of endorsement allows the CDL drivers who want to drive school buses for commuting school children, to and from school and other school based activities or school events. This endorsement is necessary to ensure the safety of school going children.

4. Tank Vehicle Endorsement (N) 

Tank vehicles are used for transporting different types of materials such as liquids or gasses. Transporting these materials also requires endorsement to ensure the skillfulness of CDL drivers, so that they might have the skills and abilities to handle and manage these specific vehicles.

5. Double / Triple Trailers Endorsement (T) 

There are some multitasking CDL drivers who want to be the authorized drivers, so that they may operate multiple trailers or combinations of vehicles, at the same time. This endorsement is required to drive and manage double or triple trailers due to their complex controlling mechanism and  composition.

6. Combination Tank and Hazardous Materials Endorsement (X) 

Some CDL drivers operate the tank vehicles for transporting some kind of hazardous materials such as hazardous liquids or gaseous materials. This (X) endorsement authorizes these drivers to drive these tank vehicles.

CDL Restrictions

There are certain limitations that are placed on the CDL drivers depending on the age, qualifications, health, medical or vehicle type. Given below are some of the most common CDL restrictions with their restriction codes.

1. Automatic Transmission Restriction (E)

Nowadays mostly modern vehicles come with an automatic transmission, so if you have driving skills to operate those types of vehicles, you will be allowed to operate vehicles only with automatic transmission. In the same way, the CDL driver only having the skills to operate the vehicles with the manual transmission, will be placed in the manual transmission restriction.

2. Air Brakes Restriction (L)

This air brake restriction indicates that a specific driver is not authorized to operate a vehicle equipped with air brakes, in case  he fails to pass the air brakes knowledge test. In other words, if you fail to pass the skills test to operate a vehicle equipped with the airbrakes, you'll be prohibited from operating any such vehicles with air brakes.

3. Medical Variance Restriction (M) 

In this case if a driver has some medical issues, disqualifying him from acquiring a CDL even under the normal circumstances, he can also apply for obtaining CDL on the basis of medical variance. 

4. Tank Vehicle Restriction (N)

Being failed to succeed the tank vehicle operating test, places you in the tank Vehicle restriction (N).  In such a situation you are not allowed to operate the tank vehicles.

5. Other Restriction (O) 

A CDL holder who fails in the skills or written test for operating the class A or class B passenger vehicles such as buses or shuttles, falls under the O restriction category, restricting him to operate those specific passenger vehicles.

6. Medical Examiner's Certificate Restriction (V)

In case you failed to obtain an authentic or legitimate Medical certification, you have to face this (V) restriction, making you disqualified to operate commercial vehicles.

7. No Full Air Brake Equipped CMV Restriction (Z) 

CDL Drivers who failed to operate the vehicles with full air brakes by not showing satisfactory performance in specific skills and knowledge tests, will fall under the category of this (Z) restriction. This will restrict them from operating CMVs (commercial motor vehicles) provided with full brakes.


Proficiency in understanding the variations of CDL classes, endorsements, and restrictions is very crucial for polishing your driving skills and expanding your employment opportunities. Mastering the knowledge of each class, competencies in knowing the vehicle types, acquiring the information of endorsements, and awareness of restrictions, all of these are the important factors for operating the vehicle's safely and efficiently. Furnishing yourself with the driving skills and abilities will open tha career gateways full of opportunities to outshine in the trucking industry. 

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