A $2-$lane $($each lane $13$ ft $)$ horizontal curve in a level

terrain has a superelevation of $6\%$ and is designed for a

speed of $65m\frac{i}{h}($choose $f_s=0\mathrm{.}115).$ The semi$-$tangent

distance $($T$)$ is $400$ ft $,$ and the EC $($End of Curve, or PT

in some books$)$ is at the Station $100+00\mathrm{.}00ft.$ a$)$ Find the

minimum radius for the road. b$)$ What is the Station for

P$.$I.? c$)$ What is the minimum distance from the edge of

the road $($along the curve$)$ where a building can be

constructed?