Q.21 Which of the following traffic sources will cause noise of the highest level during operation?
- AInland water traffic
- BJet aircraft at the take-off stageCorrect
- CRoad traffic
- DRail traffic
Solution
Concept
Jet aircraft at take-off produce the highest noise level of all common traffic sources, about 120-140 dB near the source.
Step-by-step solution
1. Compare typical noise levels of each source. 2. Inland water traffic: low, about 60-75 dB. 3. Road traffic: about 70-90 dB. 4. Rail traffic: about 80-100 dB. 5. Jet aircraft at take-off: about 120-140 dB, the highest. 6. So the answer is (B).
Explanation
At take-off, jet engines work at full thrust, so they make very loud noise. This noise is much higher than road, rail or water traffic. That is why airports need noise control zones.
Why the other options are wrong
A: Boats and ships make low noise. C: Road traffic is loud but much less than jets. D: Rail traffic is louder than road traffic but still below jet take-off.
Shortcut
Jet take-off is the loudest common transport noise (above 120 dB, near the pain threshold).
Common mistake
Choosing rail traffic because trains feel very loud when close.
Correct answer: B) Jet aircraft at the take-off stage