The 'valley curve' on a highway is provided at:
Choose the correct answer
Crest (summit) of a hill
Change from downgrade to upgrade (concave upward, valley/sag curve) — governed by night headlight SSD
Horizontal curves only
Beginning of a tunnel
Correct Answer
B. Change from downgrade to upgrade (concave upward, valley/sag curve) — governed by night headlight SSD
AI Detailed Explanation & IS Code Reference
Unlock the reasoning, formula path and code-linked notes inside your student dashboard.
Valley curve (sag vertical curve): at change from downgrade to upgrade (concave upward). Design criteria: comfort (centrifugal acceleration ≤ 0.6 m/s²); headlight sight distance at night (beam illuminates SSD). Length L = Ns²/9.6 (for headlights) where N = algebraic difference in grades (%). Valley curves have no drainage problem but affect night visibility.
ScoreCardAI links this solution with subject, topic and difficulty signals so your scorecard can identify weak areas after a full mock test.
Practice more Civil Engineering questions
This MCQ belongs to JE Level Premium Test Series. Full tests include timed attempts, rank comparison and subject-wise analysis.