Curve In Curve

Please READ MORE for the video. 

Curve in curve and different degrees curves in a curve are not so suitable for the safety on the railways if they are closer than the train length, also consecutive opposite way curves too. But sometimes landforms force to do those. Beside, forces occur in many different directions on those curves. Rail and rail head angles, wheel surface and flange angles more important on that kind of track sections. Eventually, track technical specifications generally contain substances about;
Distance between curves,
Minimum curve radius,                                                                               
Superelevation
Videos :

https://www.youtube.com/watch?v=5-vkr_Nu2n0
https://www.youtube.com/watch?v=2-Uua85kcNU&t=1s 

https://www.youtube.com/watch?v=D7J-16DBV6w 

https://www.youtube.com/watch?v=jugVvoLuiKs
Drawing : 

Akira Matsumoto
Music :
Beatles – Twist and shout