When inspecting doubles/triples, why is it important to check that the trailers are connected in the proper order and all glad hands and electrical connections are correct?

Doubles/triples connection inspection: With multiple trailers and dollies, there are many air and electrical connections, and they must ALL be correct: AIR LINES (glad hands): Service and emergency lines connected at each coupling point (tractor-to-trailer, through dollies, to each trailer); a missed or crossed connection means a trailer's brakes won't work properly.

Electrical: Connections at each point so all trailers have working lights, signals, and ABS.

Proper sequence: Trailers connected in the right order (heaviest first); all connections secured, not leaking, not dragging or tangled.

Leak/function test: Charge the air system and verify ALL trailers' brakes apply and release; check all lights on all trailers.

Why critical: A trailer at the rear with no air connection has no brakes — extremely dangerous; a missed electrical connection means no brake lights or signals on that trailer; the complexity of multiple connection points makes careful inspection essential; MORE TRAILERS = MORE CONNECTIONS = MORE TO CHECK; drivers must systematically verify every coupling, air, and electrical connection on every trailer and dolly; this thoroughness is a defining requirement of doubles/triples operation and is tested on the endorsement.