Doubles/Triples Endorsement
A doubles/triples endorsement (T endorsement) on a CDL authorizes a driver to pull two or three trailers simultaneously. It is required to operate any combination vehicle with more than one trailer, including twin 28-foot pup trailers common in regional LTL operations.
In Depth
The T endorsement requires a written knowledge test covering the unique handling, braking, and coupling characteristics of multi-trailer combinations. Doubles and triples have different turning radii, brake lag times, and stability profiles than standard semi-trailer combinations.
Doubles are most commonly used in LTL operations where carriers pull two 28-foot pup trailers to increase freight volume per driver. Some western states allow triple 53-foot trailer combinations (Rocky Mountain doubles and turnpike doubles), though these require additional permits.
Not all states allow double and triple combinations. 13 states, primarily in the eastern US, restrict doubles and triples on certain roads. Drivers must know the regulations of each state in their operating region.
Usage Example
Example: 'My T endorsement lets me pull doubles for UPS Freight. Two 28-footers carry more freight per trip than a single 53-footer.'
Related Calculators
Related Terms
CDL (Commercial Driver's License)
A Commercial Driver's License (CDL) is a specialized license required to operate large commercial vehicles including semi-trucks, buses, and tankers. CDL classes are A, B, and C depending on vehicle type and weight.
LTL (Less Than Truckload)
LTL (Less Than Truckload) is a freight shipping method where multiple shippers share space on the same truck, each paying for only the portion of the trailer they use. LTL is used for shipments too large for parcel carriers but too small to fill a full trailer.
FTL (Full Truckload)
FTL (Full Truckload) is a freight shipping method where a single shipper's goods fill an entire trailer. The shipper pays for exclusive use of the truck, and freight moves directly from origin to destination without intermediate stops.
Frequently Asked Questions
How do I get a doubles/triples endorsement?
Pass the CDL doubles/triples knowledge test at your state DMV. No separate skills test is required beyond your standard CDL.