$(30$ points$)$ A two$-$mile long racetrack is to be designed with $\frac{1}{2}$ mile long turns $($half circle$)$ at each end. If the superelevation rate for the turn section is $8\%$ and the design speed is $70$ mph $,$ is this rack track safe? Why?

For one turn, if the station of PI is $100+50,$ find the station of PC and PT $.$