elevation difference between the high point and the PVT$?$

$2.$ A highway reconstruction project is being undertaken to reduce crash rates. The reconstruction involves a major realignment of the highway such that a $55m\frac{i}{h}r$ design speed is attained. At one point on the highway, a $720-ft$ equal tangent crest vertical curve exists. Measurements show that at a station $3+40$ from the PVC$,$ the vertical curve offset is $3\mathrm{.}5ft.$ Assess the adequacy of this existing curve in light of the reconstruction design speed of $55m\frac{i}{h}r,$ and if the existing curve is inadequate, compute a satisfactory curve length.?