A vertical curve is needed to join to tangents; G₁=1% and G2-4%. Assuming a level grade (0%) for braking, and the AASHTO recommended values for deceleration and perception-reaction time, calculate the minimum length of curve (ft) needed to satisfy the safety criteria. The design speed is 60 mph. Response Feedback: G2-G₁ is positive, therefore a sag curve. A=3 SSD(0%)=565.5 ft If you assume SL, Lmin-340 ft. SSD is greater than Lmin. The assumption is good.
A vertical curve is needed to join to tangents; G₁=1% and G2-4%. Assuming a level grade (0%) for braking, and the AASHTO recommended values for deceleration and perception-reaction time, calculate the minimum length of curve (ft) needed to satisfy the safety criteria. The design speed is 60 mph. Response Feedback: G2-G₁ is positive, therefore a sag curve. A=3 SSD(0%)=565.5 ft If you assume SL, Lmin-340 ft. SSD is greater than Lmin. The assumption is good.
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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Transcribed Image Text:A vertical curve is needed to join to tangents; G₁=1% and G2-4%. Assuming a level grade (0%) for braking, and
the AASHTO recommended values for deceleration and perception-reaction time, calculate the minimum length
of curve (ft) needed to satisfy the safety criteria. The design speed is 60 mph.
Response
Feedback:
G2-G₁ is positive, therefore a sag curve.
A=3
SSD(0%)=565.5 ft
If you assume S<L,<l, Lmin=404 ft. SSD is not less than Lmin. The assumption does not
hold.
If you assume S>L, Lmin-340 ft. SSD is greater than Lmin. The assumption is good.
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