What is the safest way to make a lane change or merge with a doubles/triples combination?

Doubles/triples lane changes and merging: The long combination and rearward amplification require careful, planned maneuvers:

Plan ahead: Anticipate the lane change or merge well in advance.

Signal early: Give other drivers ample warning.

Check thoroughly: Check all mirrors and the multiple, large blind spots (more trailers = more blind areas).

Gradual and smooth: Change lanes slowly and smoothly — sudden moves trigger the 'crack-the-whip' amplification, which can swing the rear trailer into another lane or cause instability.

Allow space/time: The long combination needs plenty of room and takes more time to fully complete the lane change (all trailers must clear); ensure the gap is large enough.

Merging: Match speed, plan the merge, signal, and move smoothly into a large gap.

Avoid: Quick lane changes, weaving, and abrupt corrections.

Remember: While you've started moving the tractor, the rear trailer is still amplifying that input and following behind — give it time and room; the combination of length, blind spots, and amplification makes smooth, well-planned, well-signaled lane changes essential; this is a key safe-driving practice for multi-trailer combinations tested on the endorsement.