Final answer:
Warning signs should be posted in intervals not to exceed one car length, or approximately 16 feet.
Step-by-step explanation:
The warning signs should be posted in intervals not to exceed one car length or a distance of approximately 16 feet.
This ensures that drivers have enough time to react and slow down when approaching a hazard or potential danger.
Posting warning signs at regular intervals helps to effectively communicate important information to drivers, promoting road safety.