Question $4(25$ pts $)$: Due to crashes at a railroad crossing, an overpass $($with a roadway surface $26$ ft above the existing

road$)$ is be constructed on an existing highway with a $-1\%$ grade. Sec illustration below. The existing highway has a design

speed of $55m\frac{i}{h}r.$ The overpass structure is to be level and centered above the railroad. Assume that the sag and crest

vertical curves are directly connected $($i$.$e$.,$ there is no constant grade section$).$ Determine the length from the PVC of the

sag vertical curve to the PVT of the crest vertical curve. Hint: you will need to first solve for the grade of the connecting

tangent indicated in the drawing. This connecting tangent is the final grade of the sag vertical curve and the initial grade of

the crest vertical curve.