Book

This informative book is designed for students who want to pass the quiz with confidence. Packed with clear explanations and visual examples, it keeps you engaged while helping you learn faster and succeed.

1. Selective barriers

Selective barriers are types of barriers that allow certain people, vehicles, or objects to pass through while blocking or restricting others. They are commonly used for security, traffic control, or access management—letting only authorized or specific types of traffic through.

  • Boom gates / barrier arms - Allows vehicles one at a time (with a pass or payment).
  • Toll gates - Allows vehicles after paying tolls or using an electronic pass.
  • Access-controlled bollards - Lower or retract only for authorized vehicles.
  • Turnstiles - Allows one person at a time with a ticket or ID.
  • Smart gates - Use sensors or IDs to decide who/what can pass.
Selective barriers

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