CDL Doubles/Triples Endorsement
The Doubles/Triples endorsement authorizes you to tow double or triple trailers. These combination vehicles require specialized knowledge of coupling, uncoupling, handling characteristics, and braking systems unique to multi-trailer configurations. This endorsement is most commonly used by LTL (less-than-truckload) carriers who regularly run double trailers between terminals.
Requirements
What you need to qualify for and obtain the Doubles/Triples (T) endorsement.
CDL Test Study Topics
Focus your study time on these key knowledge areas for the T endorsement written test.
- Coupling and uncoupling double and triple trailers
- Air brake systems for multi-trailer combinations
- Handling characteristics and turning radius differences
- Inspection procedures for multiple trailers
- Rearward amplification (crack-the-whip effect)
- State-specific restrictions on doubles and triples routes
Jobs That Require the T Endorsement
Earning Potential
Annual Pay Boost
+$3,000 - $8,000/year
Demand Level
Moderate to High
Drivers with the T endorsement earn +$3,000 - $8,000/year more annually than non-endorsed CDL holders. The moderate to high demand ensures consistent job availability and strong negotiating leverage.
Top States for T-Endorsed Drivers
These states have the highest demand for drivers with the Doubles/Triples endorsement.
Frequently Asked Questions
Where can I drive triple trailers?
Triple trailers are only allowed in certain western and midwestern states (including Indiana, Montana, Nevada, Oregon, and Utah) on designated routes. Most eastern states prohibit triples entirely. Double trailers are allowed nationwide on approved routes.
Which companies need Doubles/Triples endorsement most?
LTL carriers are the primary employers: FedEx Freight, Old Dominion, XPO Logistics, Estes Express, and Saia all regularly run double trailers. UPS Freight and USPS contractors also use doubles heavily for linehaul operations.
Is the Doubles/Triples test difficult?
It is one of the easier CDL endorsement tests. The 20-question written exam covers coupling procedures, air brakes for multiples, and handling characteristics. Most drivers pass on the first attempt after 1-2 hours of study.