Traffic Signs & Signals — Mississippi
Mississippi CDL practice test: 463 free practice questions (Based on the official driver handbook). The official format is not yet verified; check the official site before your test. Traffic Signs & Signals: 3 questions.
Regulatory, warning and guide signs, plus traffic light and pavement marking questions.
This topic page is still being reviewed against the official handbook. Until review is finished it is hidden from search engines.
| Topic / Metric | Value |
|---|---|
| Topic | Traffic Signs & Signals |
| License test | Mississippi CDL permit (CLP) knowledge tests |
| Topic questions | 3 (1% of 463 total) |
| Review status | This topic page is still being reviewed against the official handbook. Until review is finished it is hidden from search engines. |
Official handbook
Not yet verified
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Questions (3)
1. What does the trailer air supply control look like?
- It is a square blue knob.
- It is a triangular yellow knob.
- It is an eight-sided red knob. ✓
- It is a circular orange knob.
Answer: C. It is an eight-sided red knob.
The trailer air supply control on newer vehicles is a red eight-sided knob. The handbook describes the trailer air supply control in the cab, which operates the tractor protection valve. On newer vehicles it is a red knob with eight sides. You push it in to send air to the trailer and pull it out to cut the air off and apply the trailer emergency brakes. The same knob pops out on its own when air pressure falls to roughly 20 to 45 psi, closing the tractor protection valve. Older vehicles may instead have a lever rather than a knob.
2. A driver should test the tractor protection valve by:
- Pulling the yellow, diamond-shaped knob.
- Releasing air with the brake pedal. ✓
- Unlocking the trailer doors.
Answer: B. Releasing air with the brake pedal.
3. If you doubt that you have enough space to safely drive under a bridge or sign, you should:
- Drive faster.
- Drive more slowly. ✓
- Drive on the shoulder.
Answer: B. Drive more slowly.
You should drive more slowly when you are not sure you have enough space to drive under a bridge or sign. The handbook says that if you doubt you have safe space to pass under an object, you should go slowly. It also says that if you are not sure you can make it, take another route. It notes that low bridges and underpasses often have warning signs, but sometimes they do not. That makes doubt a reason to be cautious, not to try the clearance at higher speed.
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Last checked: 2026-10-17 · Not yet verified
Updated: · Based on the official driver handbook