This online practice test covers all of the information needed to pass the CDL knowledge test for driving safely with double and triple trailers. The material covers information on how important it is to be very careful when driving with more than one trailer, how to couple and uncouple correctly, and how to inspect doubles and triples carefully.
Doubles and Triples are specifically covered in Section 7 of the CDL manual. The included online practice test covers material specifically on Doubles and Triples to help applicants pass the T endorsement written test.
However, drivers of doubles and triples should also be familiar and will need to ultimately know Sections 2 (Driving Safely), Section 5 (Air Brakes) and Section 6 (Combination Vehicles).