California Car / Permit practice question · Road Signs
A diamond-shaped placard displayed on the back of a truck warns other drivers that the vehicle:
Answer choices
- May be carrying a hazardous load and must stop before railroad tracks— Correct answer
- Is a slow-moving farm vehicle traveling 25 mph or less
- Is exempt from all posted speed limits
- Is authorized to use carpool lanes at any time
Why this is the answer
A diamond-shaped sign on a truck means its load may be dangerous, such as gas or explosives. Vehicles carrying these placards must stop before crossing railroad tracks. That is the rule the placard triggers, so watch for the stop. Slow-moving vehicles carry a different marking, an orange and red triangle, rather than this diamond.
Source: California Driver Handbook — Vehicles with Hazardous Loads
Content reviewed against official driver handbooks · August 12, 2026
More Road Signs questions
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