Question

A vertical curve crosses a 4-ft diameter pipe at right angles. The pipe centerline is located at 110+85 and its centerline is at elevation 1091.60ft. The PVI of the vertical curve is at 110+00 and elevation 1098.4ft. The vertical curve is equal tangent, 600ft long, and connects an initial grade of +1.20% with a final grade of −1.08%. Does this vertical curve provide sufficient stopping sight distance for a speed of 60mph ?

a. Lm=343.27ft and design is invalid
b. Lm=343.27ft and design is valid c. Lm=193.51ft and design is invalid d. Lm=193.51ft and design is valid

Answer 1

The given vertical curve provides sufficient stopping sight distance for a speed of 60mph.

Step-by-step explanation:

The question asks whether the given vertical curve provides sufficient stopping sight distance for a speed of 60mph. To determine this, we need to calculate the required stopping distance and compare it to the available sight distance on the curve.

The required stopping distance at 60mph can be calculated as: (60mph)^2 / (30 x 0.078) = 457.85ft.

The available sight distance on the curve, Lm, can be calculated as: 600ft - [(60mph / 2) x (1.47s / 5280ft)] = 193.51ft.

Therefore, the answer is d. Lm=193.51ft and design is valid.