a large grain elevator is located $40$ ft from the centerline of a two$-$lane highway $(55$ mph speed limit$,12-$ft lane$).$ the elevator is situated on the inside of a horizontal curve with a raduis of $500$ft$,$ measured to the center of the innermost lane. Assuming that the elevator is the only sight restriction on the curve, what is the minimum sight distance along the cur $($measured to the center of the inside lane$)?$ Does adequate stopping sight distance exist? if not, what action should e taken?