A vertical curve is needed to join to tangents; G₁=2% and G2-5%. Assuming the worst case scenario for braking, and the AASHTO recommended values for deceleration and perception-reaction time, calculate the minimum length of curve (ft) needed to satisfy the appearance criteria. The design speed is 50 mph. Response Feedback: G2-G₁ is positive, therefore a sag curve. A=3 Lmin=100A

A vertical curve is needed to join to tangents; G₁=2% and G2-5%. Assuming the worst case scenario for braking, and the AASHTO recommended values for deceleration and perception-reaction time, calculate the minimum length of curve (ft) needed to satisfy the appearance criteria. The design speed is 50 mph. Response Feedback: G2-G₁ is positive, therefore a sag curve. A=3 Lmin=100A

Traffic and Highway Engineering

5th Edition

ISBN:9781305156241

Author:Garber, Nicholas J.

Publisher:Garber, Nicholas J.

Chapter15: Geometric Design Of Highway Facilities

Section: Chapter Questions

Problem 19P

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A vertical curve is needed to join to tangents; G₁-5% and G2-2%. Assuming the worst case scenario 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 50 mph. Response Feedback: G2-G₁ is negative, therefore a crest curve. A=3 SSD(-G1)=463.6 ft If you assume SL, Lmin=208 ft. SSD is greater than Lmin. The assumption is good.
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