An
existing equal-tangent sag vertical curve is designed for 60 mi/h.
The initial grade is -3% and the elevation of the PVT is 754 ft.
The PVC of the curve is at station 134 + 16 and the PVI is at 137 +
32. An overpass is being constructed directly above the PVI. The
highway is for cars only (AASHTO minimum and recommended structure
clearances do not apply) and the overpass design assumes the
driver's eye height is set conservatively to 5 ft. What is the
lowest possible elevation of the bottom of the overpass structure
to ensure sufficient stopping sight distance at 60 mi/h